Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Continued user-access cleanups in the futex code.

   - percpu-rwsem rewrite that uses its own waitqueue and atomic_t
     instead of an embedded rwsem. This addresses a couple of
     weaknesses, but the primary motivation was complications on the -rt
     kernel.

   - Introduce raw lock nesting detection on lockdep
     (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal
     lock differences. This too originates from -rt.

   - Reuse lockdep zapped chain_hlocks entries, to conserve RAM
     footprint on distro-ish kernels running into the "BUG:
     MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep
     chain-entries pool.

   - Misc cleanups, smaller fixes and enhancements - see the changelog
     for details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
  fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
  thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
  Documentation/locking/locktypes: Minor copy editor fixes
  Documentation/locking/locktypes: Further clarifications and wordsmithing
  m68knommu: Remove mm.h include from uaccess_no.h
  x86: get rid of user_atomic_cmpxchg_inatomic()
  generic arch_futex_atomic_op_inuser() doesn't need access_ok()
  x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
  x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()
  objtool: whitelist __sanitizer_cov_trace_switch()
  [parisc, s390, sparc64] no need for access_ok() in futex handling
  sh: no need of access_ok() in arch_futex_atomic_op_inuser()
  futex: arch_futex_atomic_op_inuser() calling conventions change
  completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()
  lockdep: Add posixtimer context tracing bits
  lockdep: Annotate irq_work
  lockdep: Add hrtimer context tracing bits
  lockdep: Introduce wait-type checks
  completion: Use simple wait queues
  sched/swait: Prepare usage in completions
  ...

Documentation/locking/index.rst

@@ -7,6 +7,7 @@ locking
 .. toctree::
     :maxdepth: 1
 
+    locktypes
     lockdep-design
     lockstat
     locktorture

Documentation/locking/locktypes.rst

@@ -0,0 +1,347 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _kernel_hacking_locktypes:
+
+==========================
+Lock types and their rules
+==========================
+
+Introduction
+============
+
+The kernel provides a variety of locking primitives which can be divided
+into two categories:
+
+ - Sleeping locks
+ - Spinning locks
+
+This document conceptually describes these lock types and provides rules
+for their nesting, including the rules for use under PREEMPT_RT.
+
+
+Lock categories
+===============
+
+Sleeping locks
+--------------
+
+Sleeping locks can only be acquired in preemptible task context.
+
+Although implementations allow try_lock() from other contexts, it is
+necessary to carefully evaluate the safety of unlock() as well as of
+try_lock().  Furthermore, it is also necessary to evaluate the debugging
+versions of these primitives.  In short, don't acquire sleeping locks from
+other contexts unless there is no other option.
+
+Sleeping lock types:
+
+ - mutex
+ - rt_mutex
+ - semaphore
+ - rw_semaphore
+ - ww_mutex
+ - percpu_rw_semaphore
+
+On PREEMPT_RT kernels, these lock types are converted to sleeping locks:
+
+ - spinlock_t
+ - rwlock_t
+
+Spinning locks
+--------------
+
+ - raw_spinlock_t
+ - bit spinlocks
+
+On non-PREEMPT_RT kernels, these lock types are also spinning locks:
+
+ - spinlock_t
+ - rwlock_t
+
+Spinning locks implicitly disable preemption and the lock / unlock functions
+can have suffixes which apply further protections:
+
+ ===================  ====================================================
+ _bh()                Disable / enable bottom halves (soft interrupts)
+ _irq()               Disable / enable interrupts
+ _irqsave/restore()   Save and disable / restore interrupt disabled state
+ ===================  ====================================================
+
+Owner semantics
+===============
+
+The aforementioned lock types except semaphores have strict owner
+semantics:
+
+  The context (task) that acquired the lock must release it.
+
+rw_semaphores have a special interface which allows non-owner release for
+readers.
+
+
+rtmutex
+=======
+
+RT-mutexes are mutexes with support for priority inheritance (PI).
+
+PI has limitations on non-PREEMPT_RT kernels due to preemption and
+interrupt disabled sections.
+
+PI clearly cannot preempt preemption-disabled or interrupt-disabled
+regions of code, even on PREEMPT_RT kernels.  Instead, PREEMPT_RT kernels
+execute most such regions of code in preemptible task context, especially
+interrupt handlers and soft interrupts.  This conversion allows spinlock_t
+and rwlock_t to be implemented via RT-mutexes.
+
+
+semaphore
+=========
+
+semaphore is a counting semaphore implementation.
+
+Semaphores are often used for both serialization and waiting, but new use
+cases should instead use separate serialization and wait mechanisms, such
+as mutexes and completions.
+
+semaphores and PREEMPT_RT
+----------------------------
+
+PREEMPT_RT does not change the semaphore implementation because counting
+semaphores have no concept of owners, thus preventing PREEMPT_RT from
+providing priority inheritance for semaphores.  After all, an unknown
+owner cannot be boosted. As a consequence, blocking on semaphores can
+result in priority inversion.
+
+
+rw_semaphore
+============
+
+rw_semaphore is a multiple readers and single writer lock mechanism.
+
+On non-PREEMPT_RT kernels the implementation is fair, thus preventing
+writer starvation.
+
+rw_semaphore complies by default with the strict owner semantics, but there
+exist special-purpose interfaces that allow non-owner release for readers.
+These interfaces work independent of the kernel configuration.
+
+rw_semaphore and PREEMPT_RT
+---------------------------
+
+PREEMPT_RT kernels map rw_semaphore to a separate rt_mutex-based
+implementation, thus changing the fairness:
+
+ Because an rw_semaphore writer cannot grant its priority to multiple
+ readers, a preempted low-priority reader will continue holding its lock,
+ thus starving even high-priority writers.  In contrast, because readers
+ can grant their priority to a writer, a preempted low-priority writer will
+ have its priority boosted until it releases the lock, thus preventing that
+ writer from starving readers.
+
+
+raw_spinlock_t and spinlock_t
+=============================
+
+raw_spinlock_t
+--------------
+
+raw_spinlock_t is a strict spinning lock implementation regardless of the
+kernel configuration including PREEMPT_RT enabled kernels.
+
+raw_spinlock_t is a strict spinning lock implementation in all kernels,
+including PREEMPT_RT kernels.  Use raw_spinlock_t only in real critical
+core code, low-level interrupt handling and places where disabling
+preemption or interrupts is required, for example, to safely access
+hardware state.  raw_spinlock_t can sometimes also be used when the
+critical section is tiny, thus avoiding RT-mutex overhead.
+
+spinlock_t
+----------
+
+The semantics of spinlock_t change with the state of PREEMPT_RT.
+
+On a non-PREEMPT_RT kernel spinlock_t is mapped to raw_spinlock_t and has
+exactly the same semantics.
+
+spinlock_t and PREEMPT_RT
+-------------------------
+
+On a PREEMPT_RT kernel spinlock_t is mapped to a separate implementation
+based on rt_mutex which changes the semantics:
+
+ - Preemption is not disabled.
+
+ - The hard interrupt related suffixes for spin_lock / spin_unlock
+   operations (_irq, _irqsave / _irqrestore) do not affect the CPU's
+   interrupt disabled state.
+
+ - The soft interrupt related suffix (_bh()) still disables softirq
+   handlers.
+
+   Non-PREEMPT_RT kernels disable preemption to get this effect.
+
+   PREEMPT_RT kernels use a per-CPU lock for serialization which keeps
+   preemption disabled. The lock disables softirq handlers and also
+   prevents reentrancy due to task preemption.
+
+PREEMPT_RT kernels preserve all other spinlock_t semantics:
+
+ - Tasks holding a spinlock_t do not migrate.  Non-PREEMPT_RT kernels
+   avoid migration by disabling preemption.  PREEMPT_RT kernels instead
+   disable migration, which ensures that pointers to per-CPU variables
+   remain valid even if the task is preempted.
+
+ - Task state is preserved across spinlock acquisition, ensuring that the
+   task-state rules apply to all kernel configurations.  Non-PREEMPT_RT
+   kernels leave task state untouched.  However, PREEMPT_RT must change
+   task state if the task blocks during acquisition.  Therefore, it saves
+   the current task state before blocking and the corresponding lock wakeup
+   restores it, as shown below::
+
+    task->state = TASK_INTERRUPTIBLE
+     lock()
+       block()
+         task->saved_state = task->state
+	 task->state = TASK_UNINTERRUPTIBLE
+	 schedule()
+					lock wakeup
+					  task->state = task->saved_state
+
+   Other types of wakeups would normally unconditionally set the task state
+   to RUNNING, but that does not work here because the task must remain
+   blocked until the lock becomes available.  Therefore, when a non-lock
+   wakeup attempts to awaken a task blocked waiting for a spinlock, it
+   instead sets the saved state to RUNNING.  Then, when the lock
+   acquisition completes, the lock wakeup sets the task state to the saved
+   state, in this case setting it to RUNNING::
+
+    task->state = TASK_INTERRUPTIBLE
+     lock()
+       block()
+         task->saved_state = task->state
+	 task->state = TASK_UNINTERRUPTIBLE
+	 schedule()
+					non lock wakeup
+					  task->saved_state = TASK_RUNNING
+
+					lock wakeup
+					  task->state = task->saved_state
+
+   This ensures that the real wakeup cannot be lost.
+
+
+rwlock_t
+========
+
+rwlock_t is a multiple readers and single writer lock mechanism.
+
+Non-PREEMPT_RT kernels implement rwlock_t as a spinning lock and the
+suffix rules of spinlock_t apply accordingly. The implementation is fair,
+thus preventing writer starvation.
+
+rwlock_t and PREEMPT_RT
+-----------------------
+
+PREEMPT_RT kernels map rwlock_t to a separate rt_mutex-based
+implementation, thus changing semantics:
+
+ - All the spinlock_t changes also apply to rwlock_t.
+
+ - Because an rwlock_t writer cannot grant its priority to multiple
+   readers, a preempted low-priority reader will continue holding its lock,
+   thus starving even high-priority writers.  In contrast, because readers
+   can grant their priority to a writer, a preempted low-priority writer
+   will have its priority boosted until it releases the lock, thus
+   preventing that writer from starving readers.
+
+
+PREEMPT_RT caveats
+==================
+
+spinlock_t and rwlock_t
+-----------------------
+
+These changes in spinlock_t and rwlock_t semantics on PREEMPT_RT kernels
+have a few implications.  For example, on a non-PREEMPT_RT kernel the
+following code sequence works as expected::
+
+   local_irq_disable();
+   spin_lock(&lock);
+
+and is fully equivalent to::
+
+   spin_lock_irq(&lock);
+
+Same applies to rwlock_t and the _irqsave() suffix variants.
+
+On PREEMPT_RT kernel this code sequence breaks because RT-mutex requires a
+fully preemptible context.  Instead, use spin_lock_irq() or
+spin_lock_irqsave() and their unlock counterparts.  In cases where the
+interrupt disabling and locking must remain separate, PREEMPT_RT offers a
+local_lock mechanism.  Acquiring the local_lock pins the task to a CPU,
+allowing things like per-CPU interrupt disabled locks to be acquired.
+However, this approach should be used only where absolutely necessary.
+
+
+raw_spinlock_t
+--------------
+
+Acquiring a raw_spinlock_t disables preemption and possibly also
+interrupts, so the critical section must avoid acquiring a regular
+spinlock_t or rwlock_t, for example, the critical section must avoid
+allocating memory.  Thus, on a non-PREEMPT_RT kernel the following code
+works perfectly::
+
+  raw_spin_lock(&lock);
+  p = kmalloc(sizeof(*p), GFP_ATOMIC);
+
+But this code fails on PREEMPT_RT kernels because the memory allocator is
+fully preemptible and therefore cannot be invoked from truly atomic
+contexts.  However, it is perfectly fine to invoke the memory allocator
+while holding normal non-raw spinlocks because they do not disable
+preemption on PREEMPT_RT kernels::
+
+  spin_lock(&lock);
+  p = kmalloc(sizeof(*p), GFP_ATOMIC);
+
+
+bit spinlocks
+-------------
+
+PREEMPT_RT cannot substitute bit spinlocks because a single bit is too
+small to accommodate an RT-mutex.  Therefore, the semantics of bit
+spinlocks are preserved on PREEMPT_RT kernels, so that the raw_spinlock_t
+caveats also apply to bit spinlocks.
+
+Some bit spinlocks are replaced with regular spinlock_t for PREEMPT_RT
+using conditional (#ifdef'ed) code changes at the usage site.  In contrast,
+usage-site changes are not needed for the spinlock_t substitution.
+Instead, conditionals in header files and the core locking implemementation
+enable the compiler to do the substitution transparently.
+
+
+Lock type nesting rules
+=======================
+
+The most basic rules are:
+
+  - Lock types of the same lock category (sleeping, spinning) can nest
+    arbitrarily as long as they respect the general lock ordering rules to
+    prevent deadlocks.
+
+  - Sleeping lock types cannot nest inside spinning lock types.
+
+  - Spinning lock types can nest inside sleeping lock types.
+
+These constraints apply both in PREEMPT_RT and otherwise.
+
+The fact that PREEMPT_RT changes the lock category of spinlock_t and
+rwlock_t from spinning to sleeping means that they cannot be acquired while
+holding a raw spinlock.  This results in the following nesting ordering:
+
+  1) Sleeping locks
+  2) spinlock_t and rwlock_t
+  3) raw_spinlock_t and bit spinlocks
+
+Lockdep will complain if these constraints are violated, both in
+PREEMPT_RT and otherwise.

arch/alpha/include/asm/futex.h

@@ -31,7 +31,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -53,8 +54,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/arc/include/asm/futex.h

@@ -75,10 +75,12 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
+
 #ifndef CONFIG_ARC_HAS_LLSC
 	preempt_disable();	/* to guarantee atomic r-m-w of futex op */
 #endif
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -101,7 +103,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
 #ifndef CONFIG_ARC_HAS_LLSC
 	preempt_enable();
 #endif

arch/arm/include/asm/futex.h

@@ -134,10 +134,12 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret, tmp;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
+
 #ifndef CONFIG_SMP
 	preempt_disable();
 #endif
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -159,7 +161,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
 #ifndef CONFIG_SMP
 	preempt_enable();
 #endif

arch/arm64/include/asm/futex.h

@@ -48,7 +48,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
 	int oldval = 0, ret, tmp;
 	u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
 
-	pagefault_disable();
+	if (!access_ok(_uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -75,8 +76,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/csky/include/asm/uaccess.h

@@ -11,7 +11,6 @@
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/sched.h>
-#include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/version.h>
 #include <asm/segment.h>

arch/hexagon/include/asm/futex.h

@@ -36,7 +36,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -62,8 +63,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/hexagon/include/asm/uaccess.h

@@ -10,7 +10,6 @@
 /*
  * User space memory access functions
  */
-#include <linux/mm.h>
 #include <asm/sections.h>
 
 /*

arch/ia64/include/asm/futex.h

@@ -50,7 +50,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -74,8 +75,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/ia64/include/asm/uaccess.h

@@ -35,7 +35,6 @@
 
 #include <linux/compiler.h>
 #include <linux/page-flags.h>
-#include <linux/mm.h>
 
 #include <asm/intrinsics.h>
 #include <asm/pgtable.h>

arch/ia64/kernel/process.c

@@ -681,3 +681,4 @@ machine_power_off (void)
 	machine_halt();
 }
 
+EXPORT_SYMBOL(ia64_delay_loop);

arch/ia64/mm/ioremap.c

@@ -8,6 +8,7 @@
 #include <linux/module.h>
 #include <linux/efi.h>
 #include <linux/io.h>
+#include <linux/mm.h>
 #include <linux/vmalloc.h>
 #include <asm/io.h>
 #include <asm/meminit.h>

arch/m68k/include/asm/uaccess_no.h

@@ -5,7 +5,6 @@
 /*
  * User space memory access functions
  */
-#include <linux/mm.h>
 #include <linux/string.h>
 
 #include <asm/segment.h>

arch/microblaze/include/asm/futex.h

@@ -34,7 +34,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -56,8 +57,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/microblaze/include/asm/uaccess.h

@@ -12,7 +12,6 @@
 #define _ASM_MICROBLAZE_UACCESS_H
 
 #include <linux/kernel.h>
-#include <linux/mm.h>
 
 #include <asm/mmu.h>
 #include <asm/page.h>

arch/mips/include/asm/futex.h

@@ -89,7 +89,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -116,8 +117,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/nds32/include/asm/futex.h

@@ -66,8 +66,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-
+	if (!access_ok(uaddr, sizeof(u32)))
-	pagefault_disable();
+		return -EFAULT;
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_atomic_op("move	%0, %3", ret, oldval, tmp, uaddr,
@@ -93,8 +93,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/nds32/include/asm/uaccess.h

@@ -11,7 +11,6 @@
 #include <asm/errno.h>
 #include <asm/memory.h>
 #include <asm/types.h>
-#include <linux/mm.h>
 
 #define __asmeq(x, y)  ".ifnc " x "," y " ; .err ; .endif\n\t"
 

arch/openrisc/include/asm/futex.h

@@ -35,7 +35,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -57,8 +58,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/parisc/include/asm/futex.h

@@ -40,7 +40,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 	u32 tmp;
 
 	_futex_spin_lock_irqsave(uaddr, &flags);
-	pagefault_disable();
 
 	ret = -EFAULT;
 	if (unlikely(get_user(oldval, uaddr) != 0))
@@ -73,7 +72,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -EFAULT;
 
 out_pagefault_enable:
-	pagefault_enable();
 	_futex_spin_unlock_irqrestore(uaddr, &flags);
 
 	if (!ret)

arch/powerpc/include/asm/futex.h

@@ -35,8 +35,9 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 	allow_read_write_user(uaddr, uaddr, sizeof(*uaddr));
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -58,8 +59,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	*oval = oldval;
 
 	prevent_read_write_user(uaddr, uaddr, sizeof(*uaddr));

arch/powerpc/platforms/ps3/device-init.c

@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/reboot.h>
+#include <linux/rcuwait.h>
 
 #include <asm/firmware.h>
 #include <asm/lv1call.h>
@@ -670,7 +671,8 @@ struct ps3_notification_device {
 	spinlock_t lock;
 	u64 tag;
 	u64 lv1_status;
-	struct completion done;
+	struct rcuwait wait;
+	bool done;
 };
 
 enum ps3_notify_type {
@@ -712,7 +714,8 @@ static irqreturn_t ps3_notification_interrupt(int irq, void *data)
 		pr_debug("%s:%u: completed, status 0x%llx\n", __func__,
 			 __LINE__, status);
 		dev->lv1_status = status;
-		complete(&dev->done);
+		dev->done = true;
+		rcuwait_wake_up(&dev->wait);
 	}
 	spin_unlock(&dev->lock);
 	return IRQ_HANDLED;
@@ -725,12 +728,12 @@ static int ps3_notification_read_write(struct ps3_notification_device *dev,
 	unsigned long flags;
 	int res;
 
-	init_completion(&dev->done);
 	spin_lock_irqsave(&dev->lock, flags);
 	res = write ? lv1_storage_write(dev->sbd.dev_id, 0, 0, 1, 0, lpar,
 					&dev->tag)
 		    : lv1_storage_read(dev->sbd.dev_id, 0, 0, 1, 0, lpar,
 				       &dev->tag);
+	dev->done = false;
 	spin_unlock_irqrestore(&dev->lock, flags);
 	if (res) {
 		pr_err("%s:%u: %s failed %d\n", __func__, __LINE__, op, res);
@@ -738,14 +741,10 @@ static int ps3_notification_read_write(struct ps3_notification_device *dev,
 	}
 	pr_debug("%s:%u: notification %s issued\n", __func__, __LINE__, op);
 
-	res = wait_event_interruptible(dev->done.wait,
+	rcuwait_wait_event(&dev->wait, dev->done || kthread_should_stop(), TASK_IDLE);
-				       dev->done.done || kthread_should_stop());
+
 	if (kthread_should_stop())
 		res = -EINTR;
-	if (res) {
-		pr_debug("%s:%u: interrupted %s\n", __func__, __LINE__, op);
-		return res;
-	}
 
 	if (dev->lv1_status) {
 		pr_err("%s:%u: %s not completed, status 0x%llx\n", __func__,
@@ -810,6 +809,7 @@ static int ps3_probe_thread(void *data)
 	}
 
 	spin_lock_init(&dev.lock);
+	rcuwait_init(&dev.wait);
 
 	res = request_irq(irq, ps3_notification_interrupt, 0,
 			  "ps3_notification", &dev);

arch/riscv/include/asm/futex.h

@@ -46,7 +46,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret = 0;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -73,8 +74,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/s390/include/asm/futex.h

@@ -29,7 +29,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	mm_segment_t old_fs;
 
 	old_fs = enable_sacf_uaccess();
-	pagefault_disable();
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_atomic_op("lr %2,%5\n",
@@ -54,7 +53,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	default:
 		ret = -ENOSYS;
 	}
-	pagefault_enable();
 	disable_sacf_uaccess(old_fs);
 
 	if (!ret)

arch/sh/include/asm/futex.h

@@ -34,8 +34,6 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval,
 	u32 oldval, newval, prev;
 	int ret;
 
-	pagefault_disable();
-
 	do {
 		ret = get_user(oldval, uaddr);
 
@@ -67,8 +65,6 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval,
 		ret = futex_atomic_cmpxchg_inatomic(&prev, uaddr, oldval, newval);
 	} while (!ret && prev != oldval);
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/sparc/include/asm/futex_64.h

@@ -38,8 +38,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	if (unlikely((((unsigned long) uaddr) & 0x3UL)))
 		return -EINVAL;
 
-	pagefault_disable();
-
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_cas_op("mov\t%4, %1", ret, oldval, uaddr, oparg);
@@ -60,8 +58,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

arch/x86/include/asm/futex.h

@@ -12,76 +12,103 @@
 #include <asm/processor.h>
 #include <asm/smap.h>
 
-#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)	\
+#define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)	\
-	asm volatile("\t" ASM_STAC "\n"				\
+do {								\
-		     "1:\t" insn "\n"				\
+	int oldval = 0, ret;					\
-		     "2:\t" ASM_CLAC "\n"			\
+	asm volatile("1:\t" insn "\n"				\
+		     "2:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
 		     "3:\tmov\t%3, %1\n"			\
 		     "\tjmp\t2b\n"				\
 		     "\t.previous\n"				\
 		     _ASM_EXTABLE_UA(1b, 3b)			\
 		     : "=r" (oldval), "=r" (ret), "+m" (*uaddr)	\
-		     : "i" (-EFAULT), "0" (oparg), "1" (0))
+		     : "i" (-EFAULT), "0" (oparg), "1" (0));	\
+	if (ret)						\
+		goto label;					\
+	*oval = oldval;						\
+} while(0)
 
-#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)	\
+
-	asm volatile("\t" ASM_STAC "\n"				\
+#define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)	\
-		     "1:\tmovl	%2, %0\n"			\
+do {								\
-		     "\tmovl\t%0, %3\n"				\
+	int oldval = 0, ret, tem;				\
+	asm volatile("1:\tmovl	%2, %0\n"			\
+		     "2:\tmovl\t%0, %3\n"			\
 		     "\t" insn "\n"				\
-		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
+		     "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
-		     "\tjnz\t1b\n"				\
+		     "\tjnz\t2b\n"				\
-		     "3:\t" ASM_CLAC "\n"			\
+		     "4:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
-		     "4:\tmov\t%5, %1\n"			\
+		     "5:\tmov\t%5, %1\n"			\
-		     "\tjmp\t3b\n"				\
+		     "\tjmp\t4b\n"				\
 		     "\t.previous\n"				\
-		     _ASM_EXTABLE_UA(1b, 4b)			\
+		     _ASM_EXTABLE_UA(1b, 5b)			\
-		     _ASM_EXTABLE_UA(2b, 4b)			\
+		     _ASM_EXTABLE_UA(3b, 5b)			\
 		     : "=&a" (oldval), "=&r" (ret),		\
 		       "+m" (*uaddr), "=&r" (tem)		\
-		     : "r" (oparg), "i" (-EFAULT), "1" (0))
+		     : "r" (oparg), "i" (-EFAULT), "1" (0));	\
+	if (ret)						\
+		goto label;					\
+	*oval = oldval;						\
+} while(0)
 
-static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
+static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		u32 __user *uaddr)
 {
-	int oldval = 0, ret, tem;
+	if (!user_access_begin(uaddr, sizeof(u32)))
-
+		return -EFAULT;
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
-		__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_ADD:
-		__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
+		unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
-				   uaddr, oparg);
+				   uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_OR:
-		__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_ANDN:
-		__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
+		unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
 		break;
 	case FUTEX_OP_XOR:
-		__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
 		break;
 	default:
-		ret = -ENOSYS;
+		user_access_end();
+		return -ENOSYS;
 	}
-
+	user_access_end();
-	pagefault_enable();
+	return 0;
-
+Efault:
-	if (!ret)
+	user_access_end();
-		*oval = oldval;
+	return -EFAULT;
-
-	return ret;
 }
 
 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 						u32 oldval, u32 newval)
 {
-	return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
+	int ret = 0;
+
+	if (!user_access_begin(uaddr, sizeof(u32)))
+		return -EFAULT;
+	asm volatile("\n"
+		"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
+		"2:\n"
+		"\t.section .fixup, \"ax\"\n"
+		"3:\tmov     %3, %0\n"
+		"\tjmp     2b\n"
+		"\t.previous\n"
+		_ASM_EXTABLE_UA(1b, 3b)
+		: "+r" (ret), "=a" (oldval), "+m" (*uaddr)
+		: "i" (-EFAULT), "r" (newval), "1" (oldval)
+		: "memory"
+	);
+	user_access_end();
+	*uval = oldval;
+	return ret;
 }
 
 #endif

arch/x86/include/asm/uaccess.h

@@ -584,99 +584,6 @@ extern __must_check long strnlen_user(const char __user *str, long n);
 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 
-extern void __cmpxchg_wrong_size(void)
-	__compiletime_error("Bad argument size for cmpxchg");
-
-#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)	\
-({									\
-	int __ret = 0;							\
-	__typeof__(*(ptr)) __old = (old);				\
-	__typeof__(*(ptr)) __new = (new);				\
-	__uaccess_begin_nospec();					\
-	switch (size) {							\
-	case 1:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "q" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 2:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 4:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 8:								\
-	{								\
-		if (!IS_ENABLED(CONFIG_X86_64))				\
-			__cmpxchg_wrong_size();				\
-									\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	default:							\
-		__cmpxchg_wrong_size();					\
-	}								\
-	__uaccess_end();						\
-	*(uval) = __old;						\
-	__ret;								\
-})
-
-#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)		\
-({									\
-	access_ok((ptr), sizeof(*(ptr))) ?		\
-		__user_atomic_cmpxchg_inatomic((uval), (ptr),		\
-				(old), (new), sizeof(*(ptr))) :		\
-		-EFAULT;						\
-})
-
 /*
  * movsl can be slow when source and dest are not both 8-byte aligned
  */

arch/xtensa/include/asm/futex.h

@@ -72,7 +72,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 #if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -99,8 +100,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 

drivers/net/wireless/intersil/orinoco/orinoco_usb.c

@@ -365,17 +365,6 @@ static struct request_context *ezusb_alloc_ctx(struct ezusb_priv *upriv,
 	return ctx;
 }
 
-
-/* Hopefully the real complete_all will soon be exported, in the mean
- * while this should work. */
-static inline void ezusb_complete_all(struct completion *comp)
-{
-	complete(comp);
-	complete(comp);
-	complete(comp);
-	complete(comp);
-}
-
 static void ezusb_ctx_complete(struct request_context *ctx)
 {
 	struct ezusb_priv *upriv = ctx->upriv;
@@ -409,7 +398,7 @@ static void ezusb_ctx_complete(struct request_context *ctx)
 
 			netif_wake_queue(dev);
 		}
-		ezusb_complete_all(&ctx->done);
+		complete_all(&ctx->done);
 		ezusb_request_context_put(ctx);
 		break;
 
@@ -419,7 +408,7 @@ static void ezusb_ctx_complete(struct request_context *ctx)
 			/* This is normal, as all request contexts get flushed
 			 * when the device is disconnected */
 			err("Called, CTX not terminating, but device gone");
-			ezusb_complete_all(&ctx->done);
+			complete_all(&ctx->done);
 			ezusb_request_context_put(ctx);
 			break;
 		}
@@ -690,11 +679,11 @@ static void ezusb_req_ctx_wait(struct ezusb_priv *upriv,
 			 * get the chance to run themselves. So we make sure
 			 * that we don't sleep for ever */
 			int msecs = DEF_TIMEOUT * (1000 / HZ);
-			while (!ctx->done.done && msecs--)
+
+			while (!try_wait_for_completion(&ctx->done) && msecs--)
 				udelay(1000);
 		} else {
-			wait_event_interruptible(ctx->done.wait,
+			wait_for_completion(&ctx->done);
-						 ctx->done.done);
 		}
 		break;
 	default:

drivers/pci/switch/switchtec.c

@@ -52,10 +52,11 @@ struct switchtec_user {
 
 	enum mrpc_state state;
 
-	struct completion comp;
+	wait_queue_head_t cmd_comp;
 	struct kref kref;
 	struct list_head list;
 
+	bool cmd_done;
 	u32 cmd;
 	u32 status;
 	u32 return_code;
@@ -77,7 +78,7 @@ static struct switchtec_user *stuser_create(struct switchtec_dev *stdev)
 	stuser->stdev = stdev;
 	kref_init(&stuser->kref);
 	INIT_LIST_HEAD(&stuser->list);
-	init_completion(&stuser->comp);
+	init_waitqueue_head(&stuser->cmd_comp);
 	stuser->event_cnt = atomic_read(&stdev->event_cnt);
 
 	dev_dbg(&stdev->dev, "%s: %p\n", __func__, stuser);
@@ -175,7 +176,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser)
 	kref_get(&stuser->kref);
 	stuser->read_len = sizeof(stuser->data);
 	stuser_set_state(stuser, MRPC_QUEUED);
-	init_completion(&stuser->comp);
+	stuser->cmd_done = false;
 	list_add_tail(&stuser->list, &stdev->mrpc_queue);
 
 	mrpc_cmd_submit(stdev);
@@ -222,7 +223,8 @@ static void mrpc_complete_cmd(struct switchtec_dev *stdev)
 		memcpy_fromio(stuser->data, &stdev->mmio_mrpc->output_data,
 			      stuser->read_len);
 out:
-	complete_all(&stuser->comp);
+	stuser->cmd_done = true;
+	wake_up_interruptible(&stuser->cmd_comp);
 	list_del_init(&stuser->list);
 	stuser_put(stuser);
 	stdev->mrpc_busy = 0;
@@ -529,10 +531,11 @@ static ssize_t switchtec_dev_read(struct file *filp, char __user *data,
 	mutex_unlock(&stdev->mrpc_mutex);
 
 	if (filp->f_flags & O_NONBLOCK) {
-		if (!try_wait_for_completion(&stuser->comp))
+		if (!stuser->cmd_done)
 			return -EAGAIN;
 	} else {
-		rc = wait_for_completion_interruptible(&stuser->comp);
+		rc = wait_event_interruptible(stuser->cmd_comp,
+					      stuser->cmd_done);
 		if (rc < 0)
 			return rc;
 	}
@@ -580,7 +583,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait)
 	struct switchtec_dev *stdev = stuser->stdev;
 	__poll_t ret = 0;
 
-	poll_wait(filp, &stuser->comp.wait, wait);
+	poll_wait(filp, &stuser->cmd_comp, wait);
 	poll_wait(filp, &stdev->event_wq, wait);
 
 	if (lock_mutex_and_test_alive(stdev))
@@ -588,7 +591,7 @@ static __poll_t switchtec_dev_poll(struct file *filp, poll_table *wait)
 
 	mutex_unlock(&stdev->mrpc_mutex);
 
-	if (try_wait_for_completion(&stuser->comp))
+	if (stuser->cmd_done)
 		ret |= EPOLLIN | EPOLLRDNORM;
 
 	if (stuser->event_cnt != atomic_read(&stdev->event_cnt))
@@ -1272,7 +1275,8 @@ static void stdev_kill(struct switchtec_dev *stdev)
 
 	/* Wake up and kill any users waiting on an MRPC request */
 	list_for_each_entry_safe(stuser, tmpuser, &stdev->mrpc_queue, list) {
-		complete_all(&stuser->comp);
+		stuser->cmd_done = true;
+		wake_up_interruptible(&stuser->cmd_comp);
 		list_del_init(&stuser->list);
 		stuser_put(stuser);
 	}

drivers/platform/x86/dell-smo8800.c

@@ -16,6 +16,7 @@
 #include <linux/interrupt.h>
 #include <linux/miscdevice.h>
 #include <linux/uaccess.h>
+#include <linux/fs.h>
 
 struct smo8800_device {
 	u32 irq;                     /* acpi device irq */

drivers/platform/x86/wmi.c

@@ -29,6 +29,7 @@
 #include <linux/uaccess.h>
 #include <linux/uuid.h>
 #include <linux/wmi.h>
+#include <linux/fs.h>
 #include <uapi/linux/wmi.h>
 
 ACPI_MODULE_NAME("wmi");

drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c

@@ -19,6 +19,7 @@
 #include <linux/acpi.h>
 #include <linux/uaccess.h>
 #include <linux/miscdevice.h>
+#include <linux/fs.h>
 #include "acpi_thermal_rel.h"
 
 static acpi_handle acpi_thermal_rel_handle;

drivers/thermal/intel/x86_pkg_temp_thermal.c

@@ -63,7 +63,7 @@ static int max_id __read_mostly;
 /* Array of zone pointers */
 static struct zone_device **zones;
 /* Serializes interrupt notification, work and hotplug */
-static DEFINE_SPINLOCK(pkg_temp_lock);
+static DEFINE_RAW_SPINLOCK(pkg_temp_lock);
 /* Protects zone operation in the work function against hotplug removal */
 static DEFINE_MUTEX(thermal_zone_mutex);
 
@@ -266,12 +266,12 @@ static void pkg_temp_thermal_threshold_work_fn(struct work_struct *work)
 	u64 msr_val, wr_val;
 
 	mutex_lock(&thermal_zone_mutex);
-	spin_lock_irq(&pkg_temp_lock);
+	raw_spin_lock_irq(&pkg_temp_lock);
 	++pkg_work_cnt;
 
 	zonedev = pkg_temp_thermal_get_dev(cpu);
 	if (!zonedev) {
-		spin_unlock_irq(&pkg_temp_lock);
+		raw_spin_unlock_irq(&pkg_temp_lock);
 		mutex_unlock(&thermal_zone_mutex);
 		return;
 	}
@@ -285,7 +285,7 @@ static void pkg_temp_thermal_threshold_work_fn(struct work_struct *work)
 	}
 
 	enable_pkg_thres_interrupt();
-	spin_unlock_irq(&pkg_temp_lock);
+	raw_spin_unlock_irq(&pkg_temp_lock);
 
 	/*
 	 * If tzone is not NULL, then thermal_zone_mutex will prevent the
@@ -310,7 +310,7 @@ static int pkg_thermal_notify(u64 msr_val)
 	struct zone_device *zonedev;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pkg_temp_lock, flags);
+	raw_spin_lock_irqsave(&pkg_temp_lock, flags);
 	++pkg_interrupt_cnt;
 
 	disable_pkg_thres_interrupt();
@@ -322,7 +322,7 @@ static int pkg_thermal_notify(u64 msr_val)
 		pkg_thermal_schedule_work(zonedev->cpu, &zonedev->work);
 	}
 
-	spin_unlock_irqrestore(&pkg_temp_lock, flags);
+	raw_spin_unlock_irqrestore(&pkg_temp_lock, flags);
 	return 0;
 }
 
@@ -368,9 +368,9 @@ static int pkg_temp_thermal_device_add(unsigned int cpu)
 	      zonedev->msr_pkg_therm_high);
 
 	cpumask_set_cpu(cpu, &zonedev->cpumask);
-	spin_lock_irq(&pkg_temp_lock);
+	raw_spin_lock_irq(&pkg_temp_lock);
 	zones[id] = zonedev;
-	spin_unlock_irq(&pkg_temp_lock);
+	raw_spin_unlock_irq(&pkg_temp_lock);
 	return 0;
 }
 
@@ -407,7 +407,7 @@ static int pkg_thermal_cpu_offline(unsigned int cpu)
 	}
 
 	/* Protect against work and interrupts */
-	spin_lock_irq(&pkg_temp_lock);
+	raw_spin_lock_irq(&pkg_temp_lock);
 
 	/*
 	 * Check whether this cpu was the current target and store the new
@@ -439,9 +439,9 @@ static int pkg_thermal_cpu_offline(unsigned int cpu)
 		 * To cancel the work we need to drop the lock, otherwise
 		 * we might deadlock if the work needs to be flushed.
 		 */
-		spin_unlock_irq(&pkg_temp_lock);
+		raw_spin_unlock_irq(&pkg_temp_lock);
 		cancel_delayed_work_sync(&zonedev->work);
-		spin_lock_irq(&pkg_temp_lock);
+		raw_spin_lock_irq(&pkg_temp_lock);
 		/*
 		 * If this is not the last cpu in the package and the work
 		 * did not run after we dropped the lock above, then we
@@ -452,7 +452,7 @@ static int pkg_thermal_cpu_offline(unsigned int cpu)
 			pkg_thermal_schedule_work(target, &zonedev->work);
 	}
 
-	spin_unlock_irq(&pkg_temp_lock);
+	raw_spin_unlock_irq(&pkg_temp_lock);
 
 	/* Final cleanup if this is the last cpu */
 	if (lastcpu)

drivers/usb/gadget/function/f_fs.c

@@ -1704,7 +1704,7 @@ static void ffs_data_put(struct ffs_data *ffs)
 		pr_info("%s(): freeing\n", __func__);
 		ffs_data_clear(ffs);
 		BUG_ON(waitqueue_active(&ffs->ev.waitq) ||
-		       waitqueue_active(&ffs->ep0req_completion.wait) ||
+		       swait_active(&ffs->ep0req_completion.wait) ||
 		       waitqueue_active(&ffs->wait));
 		destroy_workqueue(ffs->io_completion_wq);
 		kfree(ffs->dev_name);

drivers/usb/gadget/legacy/inode.c

@@ -344,7 +344,7 @@ ep_io (struct ep_data *epdata, void *buf, unsigned len)
 	spin_unlock_irq (&epdata->dev->lock);
 
 	if (likely (value == 0)) {
-		value = wait_event_interruptible (done.wait, done.done);
+		value = wait_for_completion_interruptible(&done);
 		if (value != 0) {
 			spin_lock_irq (&epdata->dev->lock);
 			if (likely (epdata->ep != NULL)) {
@@ -353,7 +353,7 @@ ep_io (struct ep_data *epdata, void *buf, unsigned len)
 				usb_ep_dequeue (epdata->ep, epdata->req);
 				spin_unlock_irq (&epdata->dev->lock);
 
-				wait_event (done.wait, done.done);
+				wait_for_completion(&done);
 				if (epdata->status == -ECONNRESET)
 					epdata->status = -EINTR;
 			} else {

fs/buffer.c

@@ -274,8 +274,7 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 	 * decide that the page is now completely done.
 	 */
 	first = page_buffers(page);
-	local_irq_save(flags);
+	spin_lock_irqsave(&first->b_uptodate_lock, flags);
-	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
 	clear_buffer_async_read(bh);
 	unlock_buffer(bh);
 	tmp = bh;
@@ -288,8 +287,7 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 		}
 		tmp = tmp->b_this_page;
 	} while (tmp != bh);
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
-	local_irq_restore(flags);
 
 	/*
 	 * If none of the buffers had errors and they are all
@@ -301,8 +299,7 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 	return;
 
 still_busy:
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
-	local_irq_restore(flags);
 	return;
 }
 
@@ -371,8 +368,7 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate)
 	}
 
 	first = page_buffers(page);
-	local_irq_save(flags);
+	spin_lock_irqsave(&first->b_uptodate_lock, flags);
-	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
 
 	clear_buffer_async_write(bh);
 	unlock_buffer(bh);
@@ -384,14 +380,12 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate)
 		}
 		tmp = tmp->b_this_page;
 	}
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
-	local_irq_restore(flags);
 	end_page_writeback(page);
 	return;
 
 still_busy:
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
-	local_irq_restore(flags);
 	return;
 }
 EXPORT_SYMBOL(end_buffer_async_write);
@@ -3342,6 +3336,7 @@ struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
 	struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
 	if (ret) {
 		INIT_LIST_HEAD(&ret->b_assoc_buffers);
+		spin_lock_init(&ret->b_uptodate_lock);
 		preempt_disable();
 		__this_cpu_inc(bh_accounting.nr);
 		recalc_bh_state();

fs/ext4/page-io.c

@@ -125,11 +125,10 @@ static void ext4_finish_bio(struct bio *bio)
 		}
 		bh = head = page_buffers(page);
 		/*
-		 * We check all buffers in the page under BH_Uptodate_Lock
+		 * We check all buffers in the page under b_uptodate_lock
 		 * to avoid races with other end io clearing async_write flags
 		 */
-		local_irq_save(flags);
+		spin_lock_irqsave(&head->b_uptodate_lock, flags);
-		bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
 		do {
 			if (bh_offset(bh) < bio_start ||
 			    bh_offset(bh) + bh->b_size > bio_end) {
@@ -141,8 +140,7 @@ static void ext4_finish_bio(struct bio *bio)
 			if (bio->bi_status)
 				buffer_io_error(bh);
 		} while ((bh = bh->b_this_page) != head);
-		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
+		spin_unlock_irqrestore(&head->b_uptodate_lock, flags);
-		local_irq_restore(flags);
 		if (!under_io) {
 			fscrypt_free_bounce_page(bounce_page);
 			end_page_writeback(page);

fs/ntfs/aops.c

@@ -92,8 +92,7 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 				"0x%llx.", (unsigned long long)bh->b_blocknr);
 	}
 	first = page_buffers(page);
-	local_irq_save(flags);
+	spin_lock_irqsave(&first->b_uptodate_lock, flags);
-	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
 	clear_buffer_async_read(bh);
 	unlock_buffer(bh);
 	tmp = bh;
@@ -108,8 +107,7 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 		}
 		tmp = tmp->b_this_page;
 	} while (tmp != bh);
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
-	local_irq_restore(flags);
 	/*
 	 * If none of the buffers had errors then we can set the page uptodate,
 	 * but we first have to perform the post read mst fixups, if the
@@ -142,8 +140,7 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 	unlock_page(page);
 	return;
 still_busy:
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
-	local_irq_restore(flags);
 	return;
 }
 

include/acpi/acpi_bus.h

@@ -80,7 +80,7 @@ bool acpi_dev_present(const char *hid, const char *uid, s64 hrv);
 
 #ifdef CONFIG_ACPI
 
-#include <linux/proc_fs.h>
+struct proc_dir_entry;
 
 #define ACPI_BUS_FILE_ROOT	"acpi"
 extern struct proc_dir_entry *acpi_root_dir;

include/asm-generic/bitops.h

@@ -4,8 +4,9 @@
 
 /*
  * For the benefit of those who are trying to port Linux to another
- * architecture, here are some C-language equivalents.  You should
+ * architecture, here are some C-language equivalents.  They should
- * recode these in the native assembly language, if at all possible.
+ * generate reasonable code, so take a look at what your compiler spits
+ * out before rolling your own buggy implementation in assembly language.
  *
  * C language equivalents written by Theodore Ts'o, 9/26/92
  */

include/asm-generic/futex.h

@@ -34,7 +34,6 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 	u32 tmp;
 
 	preempt_disable();
-	pagefault_disable();
 
 	ret = -EFAULT;
 	if (unlikely(get_user(oldval, uaddr) != 0))
@@ -67,7 +66,6 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 		ret = -EFAULT;
 
 out_pagefault_enable:
-	pagefault_enable();
 	preempt_enable();
 
 	if (ret == 0)

include/linux/buffer_head.h

@@ -22,9 +22,6 @@ enum bh_state_bits {
 	BH_Dirty,	/* Is dirty */
 	BH_Lock,	/* Is locked */
 	BH_Req,		/* Has been submitted for I/O */
-	BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise
-			  * IO completion of other buffers in the page
-			  */
 
 	BH_Mapped,	/* Has a disk mapping */
 	BH_New,		/* Disk mapping was newly created by get_block */
@@ -76,6 +73,9 @@ struct buffer_head {
 	struct address_space *b_assoc_map;	/* mapping this buffer is
 						   associated with */
 	atomic_t b_count;		/* users using this buffer_head */
+	spinlock_t b_uptodate_lock;	/* Used by the first bh in a page, to
+					 * serialise IO completion of other
+					 * buffers in the page */
 };
 
 /*

include/linux/completion.h

@@ -9,7 +9,7 @@
  * See kernel/sched/completion.c for details.
  */
 
-#include <linux/wait.h>
+#include <linux/swait.h>
 
 /*
  * struct completion - structure used to maintain state for a "completion"
@@ -25,7 +25,7 @@
  */
 struct completion {
 	unsigned int done;
-	wait_queue_head_t wait;
+	struct swait_queue_head wait;
 };
 
 #define init_completion_map(x, m) __init_completion(x)
@@ -34,7 +34,7 @@ static inline void complete_acquire(struct completion *x) {}
 static inline void complete_release(struct completion *x) {}
 
 #define COMPLETION_INITIALIZER(work) \
-	{ 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
+	{ 0, __SWAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
 
 #define COMPLETION_INITIALIZER_ONSTACK_MAP(work, map) \
 	(*({ init_completion_map(&(work), &(map)); &(work); }))
@@ -85,7 +85,7 @@ static inline void complete_release(struct completion *x) {}
 static inline void __init_completion(struct completion *x)
 {
 	x->done = 0;
-	init_waitqueue_head(&x->wait);
+	init_swait_queue_head(&x->wait);
 }
 
 /**

include/linux/irq_work.h

@@ -18,6 +18,8 @@
 
 /* Doesn't want IPI, wait for tick: */
 #define IRQ_WORK_LAZY		BIT(2)
+/* Run hard IRQ context, even on RT */
+#define IRQ_WORK_HARD_IRQ	BIT(3)
 
 #define IRQ_WORK_CLAIMED	(IRQ_WORK_PENDING | IRQ_WORK_BUSY)
 

include/linux/irqflags.h

@@ -37,7 +37,12 @@
 # define trace_softirqs_enabled(p)	((p)->softirqs_enabled)
 # define trace_hardirq_enter()			\
 do {						\
-	current->hardirq_context++;		\
+	if (!current->hardirq_context++)	\
+		current->hardirq_threaded = 0;	\
+} while (0)
+# define trace_hardirq_threaded()		\
+do {						\
+	current->hardirq_threaded = 1;		\
 } while (0)
 # define trace_hardirq_exit()			\
 do {						\
@@ -51,6 +56,40 @@ do {						\
 do {						\
 	current->softirq_context--;		\
 } while (0)
+
+# define lockdep_hrtimer_enter(__hrtimer)		\
+	  do {						\
+		  if (!__hrtimer->is_hard)		\
+			current->irq_config = 1;	\
+	  } while (0)
+
+# define lockdep_hrtimer_exit(__hrtimer)		\
+	  do {						\
+		  if (!__hrtimer->is_hard)		\
+			current->irq_config = 0;	\
+	  } while (0)
+
+# define lockdep_posixtimer_enter()				\
+	  do {							\
+		  current->irq_config = 1;			\
+	  } while (0)
+
+# define lockdep_posixtimer_exit()				\
+	  do {							\
+		  current->irq_config = 0;			\
+	  } while (0)
+
+# define lockdep_irq_work_enter(__work)					\
+	  do {								\
+		  if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
+			current->irq_config = 1;			\
+	  } while (0)
+# define lockdep_irq_work_exit(__work)					\
+	  do {								\
+		  if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
+			current->irq_config = 0;			\
+	  } while (0)
+
 #else
 # define trace_hardirqs_on()		do { } while (0)
 # define trace_hardirqs_off()		do { } while (0)
@@ -59,9 +98,16 @@ do {						\
 # define trace_hardirqs_enabled(p)	0
 # define trace_softirqs_enabled(p)	0
 # define trace_hardirq_enter()		do { } while (0)
+# define trace_hardirq_threaded()	do { } while (0)
 # define trace_hardirq_exit()		do { } while (0)
 # define lockdep_softirq_enter()	do { } while (0)
 # define lockdep_softirq_exit()		do { } while (0)
+# define lockdep_hrtimer_enter(__hrtimer)		do { } while (0)
+# define lockdep_hrtimer_exit(__hrtimer)		do { } while (0)
+# define lockdep_posixtimer_enter()		do { } while (0)
+# define lockdep_posixtimer_exit()		do { } while (0)
+# define lockdep_irq_work_enter(__work)		do { } while (0)
+# define lockdep_irq_work_exit(__work)		do { } while (0)
 #endif
 
 #if defined(CONFIG_IRQSOFF_TRACER) || \

include/linux/lockdep.h

@@ -21,6 +21,22 @@ extern int lock_stat;
 
 #include <linux/types.h>
 
+enum lockdep_wait_type {
+	LD_WAIT_INV = 0,	/* not checked, catch all */
+
+	LD_WAIT_FREE,		/* wait free, rcu etc.. */
+	LD_WAIT_SPIN,		/* spin loops, raw_spinlock_t etc.. */
+
+#ifdef CONFIG_PROVE_RAW_LOCK_NESTING
+	LD_WAIT_CONFIG,		/* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */
+#else
+	LD_WAIT_CONFIG = LD_WAIT_SPIN,
+#endif
+	LD_WAIT_SLEEP,		/* sleeping locks, mutex_t etc.. */
+
+	LD_WAIT_MAX,		/* must be last */
+};
+
 #ifdef CONFIG_LOCKDEP
 
 #include <linux/linkage.h>
@@ -111,6 +127,9 @@ struct lock_class {
 	int				name_version;
 	const char			*name;
 
+	short				wait_type_inner;
+	short				wait_type_outer;
+
 #ifdef CONFIG_LOCK_STAT
 	unsigned long			contention_point[LOCKSTAT_POINTS];
 	unsigned long			contending_point[LOCKSTAT_POINTS];
@@ -158,6 +177,8 @@ struct lockdep_map {
 	struct lock_class_key		*key;
 	struct lock_class		*class_cache[NR_LOCKDEP_CACHING_CLASSES];
 	const char			*name;
+	short				wait_type_outer; /* can be taken in this context */
+	short				wait_type_inner; /* presents this context */
 #ifdef CONFIG_LOCK_STAT
 	int				cpu;
 	unsigned long			ip;
@@ -299,8 +320,21 @@ extern void lockdep_unregister_key(struct lock_class_key *key);
  * to lockdep:
  */
 
-extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
+extern void lockdep_init_map_waits(struct lockdep_map *lock, const char *name,
-			     struct lock_class_key *key, int subclass);
+	struct lock_class_key *key, int subclass, short inner, short outer);
+
+static inline void
+lockdep_init_map_wait(struct lockdep_map *lock, const char *name,
+		      struct lock_class_key *key, int subclass, short inner)
+{
+	lockdep_init_map_waits(lock, name, key, subclass, inner, LD_WAIT_INV);
+}
+
+static inline void lockdep_init_map(struct lockdep_map *lock, const char *name,
+			     struct lock_class_key *key, int subclass)
+{
+	lockdep_init_map_wait(lock, name, key, subclass, LD_WAIT_INV);
+}
 
 /*
  * Reinitialize a lock key - for cases where there is special locking or
@@ -308,18 +342,29 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
  * of dependencies wrong: they are either too broad (they need a class-split)
  * or they are too narrow (they suffer from a false class-split):
  */
-#define lockdep_set_class(lock, key) \
+#define lockdep_set_class(lock, key)				\
-		lockdep_init_map(&(lock)->dep_map, #key, key, 0)
+	lockdep_init_map_waits(&(lock)->dep_map, #key, key, 0,	\
-#define lockdep_set_class_and_name(lock, key, name) \
+			       (lock)->dep_map.wait_type_inner,	\
-		lockdep_init_map(&(lock)->dep_map, name, key, 0)
+			       (lock)->dep_map.wait_type_outer)
-#define lockdep_set_class_and_subclass(lock, key, sub) \
+
-		lockdep_init_map(&(lock)->dep_map, #key, key, sub)
+#define lockdep_set_class_and_name(lock, key, name)		\
-#define lockdep_set_subclass(lock, sub)	\
+	lockdep_init_map_waits(&(lock)->dep_map, name, key, 0,	\
-		lockdep_init_map(&(lock)->dep_map, #lock, \
+			       (lock)->dep_map.wait_type_inner,	\
-				 (lock)->dep_map.key, sub)
+			       (lock)->dep_map.wait_type_outer)
+
+#define lockdep_set_class_and_subclass(lock, key, sub)		\
+	lockdep_init_map_waits(&(lock)->dep_map, #key, key, sub,\
+			       (lock)->dep_map.wait_type_inner,	\
+			       (lock)->dep_map.wait_type_outer)
+
+#define lockdep_set_subclass(lock, sub)					\
+	lockdep_init_map_waits(&(lock)->dep_map, #lock, (lock)->dep_map.key, sub,\
+			       (lock)->dep_map.wait_type_inner,		\
+			       (lock)->dep_map.wait_type_outer)
 
 #define lockdep_set_novalidate_class(lock) \
 	lockdep_set_class_and_name(lock, &__lockdep_no_validate__, #lock)
+
 /*
  * Compare locking classes
  */
@@ -432,6 +477,10 @@ static inline void lockdep_set_selftest_task(struct task_struct *task)
 # define lock_set_class(l, n, k, s, i)		do { } while (0)
 # define lock_set_subclass(l, s, i)		do { } while (0)
 # define lockdep_init()				do { } while (0)
+# define lockdep_init_map_waits(lock, name, key, sub, inner, outer) \
+		do { (void)(name); (void)(key); } while (0)
+# define lockdep_init_map_wait(lock, name, key, sub, inner) \
+		do { (void)(name); (void)(key); } while (0)
 # define lockdep_init_map(lock, name, key, sub) \
 		do { (void)(name); (void)(key); } while (0)
 # define lockdep_set_class(lock, key)		do { (void)(key); } while (0)
@@ -662,6 +711,21 @@ do {									\
 # define lockdep_assert_in_irq() do { } while (0)
 #endif
 
+#ifdef CONFIG_PROVE_RAW_LOCK_NESTING
+
+# define lockdep_assert_RT_in_threaded_ctx() do {			\
+		WARN_ONCE(debug_locks && !current->lockdep_recursion &&	\
+			  current->hardirq_context &&			\
+			  !(current->hardirq_threaded || current->irq_config),	\
+			  "Not in threaded context on PREEMPT_RT as expected\n");	\
+} while (0)
+
+#else
+
+# define lockdep_assert_RT_in_threaded_ctx() do { } while (0)
+
+#endif
+
 #ifdef CONFIG_LOCKDEP
 void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
 #else

include/linux/mutex.h

@@ -109,8 +109,11 @@ do {									\
 } while (0)
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)			\
-		, .dep_map = { .name = #lockname }
+		, .dep_map = {					\
+			.name = #lockname,			\
+			.wait_type_inner = LD_WAIT_SLEEP,	\
+		}
 #else
 # define __DEP_MAP_MUTEX_INITIALIZER(lockname)
 #endif

include/linux/percpu-rwsem.h

@@ -3,41 +3,52 @@
 #define _LINUX_PERCPU_RWSEM_H
 
 #include <linux/atomic.h>
-#include <linux/rwsem.h>
 #include <linux/percpu.h>
 #include <linux/rcuwait.h>
+#include <linux/wait.h>
 #include <linux/rcu_sync.h>
 #include <linux/lockdep.h>
 
 struct percpu_rw_semaphore {
 	struct rcu_sync		rss;
 	unsigned int __percpu	*read_count;
-	struct rw_semaphore	rw_sem; /* slowpath */
+	struct rcuwait		writer;
-	struct rcuwait          writer; /* blocked writer */
+	wait_queue_head_t	waiters;
-	int			readers_block;
+	atomic_t		block;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
 };
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define __PERCPU_RWSEM_DEP_MAP_INIT(lockname)	.dep_map = { .name = #lockname },
+#else
+#define __PERCPU_RWSEM_DEP_MAP_INIT(lockname)
+#endif
+
 #define __DEFINE_PERCPU_RWSEM(name, is_static)				\
 static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name);		\
 is_static struct percpu_rw_semaphore name = {				\
 	.rss = __RCU_SYNC_INITIALIZER(name.rss),			\
 	.read_count = &__percpu_rwsem_rc_##name,			\
-	.rw_sem = __RWSEM_INITIALIZER(name.rw_sem),			\
 	.writer = __RCUWAIT_INITIALIZER(name.writer),			\
+	.waiters = __WAIT_QUEUE_HEAD_INITIALIZER(name.waiters),		\
+	.block = ATOMIC_INIT(0),					\
+	__PERCPU_RWSEM_DEP_MAP_INIT(name)				\
 }
+
 #define DEFINE_PERCPU_RWSEM(name)		\
 	__DEFINE_PERCPU_RWSEM(name, /* not static */)
 #define DEFINE_STATIC_PERCPU_RWSEM(name)	\
 	__DEFINE_PERCPU_RWSEM(name, static)
 
-extern int __percpu_down_read(struct percpu_rw_semaphore *, int);
+extern bool __percpu_down_read(struct percpu_rw_semaphore *, bool);
-extern void __percpu_up_read(struct percpu_rw_semaphore *);
 
 static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
 {
 	might_sleep();
 
-	rwsem_acquire_read(&sem->rw_sem.dep_map, 0, 0, _RET_IP_);
+	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
 
 	preempt_disable();
 	/*
@@ -48,8 +59,9 @@ static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
 	 * and that once the synchronize_rcu() is done, the writer will see
 	 * anything we did within this RCU-sched read-size critical section.
 	 */
-	__this_cpu_inc(*sem->read_count);
+	if (likely(rcu_sync_is_idle(&sem->rss)))
-	if (unlikely(!rcu_sync_is_idle(&sem->rss)))
+		__this_cpu_inc(*sem->read_count);
+	else
 		__percpu_down_read(sem, false); /* Unconditional memory barrier */
 	/*
 	 * The preempt_enable() prevents the compiler from
@@ -58,16 +70,17 @@ static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
 	preempt_enable();
 }
 
-static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
+static inline bool percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
 {
-	int ret = 1;
+	bool ret = true;
 
 	preempt_disable();
 	/*
 	 * Same as in percpu_down_read().
 	 */
-	__this_cpu_inc(*sem->read_count);
+	if (likely(rcu_sync_is_idle(&sem->rss)))
-	if (unlikely(!rcu_sync_is_idle(&sem->rss)))
+		__this_cpu_inc(*sem->read_count);
+	else
 		ret = __percpu_down_read(sem, true); /* Unconditional memory barrier */
 	preempt_enable();
 	/*
@@ -76,24 +89,36 @@ static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
 	 */
 
 	if (ret)
-		rwsem_acquire_read(&sem->rw_sem.dep_map, 0, 1, _RET_IP_);
+		rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
 
 	return ret;
 }
 
 static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
 {
+	rwsem_release(&sem->dep_map, _RET_IP_);
+
 	preempt_disable();
 	/*
 	 * Same as in percpu_down_read().
 	 */
-	if (likely(rcu_sync_is_idle(&sem->rss)))
+	if (likely(rcu_sync_is_idle(&sem->rss))) {
 		__this_cpu_dec(*sem->read_count);
-	else
+	} else {
-		__percpu_up_read(sem); /* Unconditional memory barrier */
+		/*
+		 * slowpath; reader will only ever wake a single blocked
+		 * writer.
+		 */
+		smp_mb(); /* B matches C */
+		/*
+		 * In other words, if they see our decrement (presumably to
+		 * aggregate zero, as that is the only time it matters) they
+		 * will also see our critical section.
+		 */
+		__this_cpu_dec(*sem->read_count);
+		rcuwait_wake_up(&sem->writer);
+	}
 	preempt_enable();
-
-	rwsem_release(&sem->rw_sem.dep_map, _RET_IP_);
 }
 
 extern void percpu_down_write(struct percpu_rw_semaphore *);
@@ -110,29 +135,19 @@ extern void percpu_free_rwsem(struct percpu_rw_semaphore *);
 	__percpu_init_rwsem(sem, #sem, &rwsem_key);		\
 })
 
-#define percpu_rwsem_is_held(sem) lockdep_is_held(&(sem)->rw_sem)
+#define percpu_rwsem_is_held(sem)	lockdep_is_held(sem)
-
+#define percpu_rwsem_assert_held(sem)	lockdep_assert_held(sem)
-#define percpu_rwsem_assert_held(sem)				\
-	lockdep_assert_held(&(sem)->rw_sem)
 
 static inline void percpu_rwsem_release(struct percpu_rw_semaphore *sem,
 					bool read, unsigned long ip)
 {
-	lock_release(&sem->rw_sem.dep_map, ip);
+	lock_release(&sem->dep_map, ip);
-#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
-	if (!read)
-		atomic_long_set(&sem->rw_sem.owner, RWSEM_OWNER_UNKNOWN);
-#endif
 }
 
 static inline void percpu_rwsem_acquire(struct percpu_rw_semaphore *sem,
 					bool read, unsigned long ip)
 {
-	lock_acquire(&sem->rw_sem.dep_map, 0, 1, read, 1, NULL, ip);
+	lock_acquire(&sem->dep_map, 0, 1, read, 1, NULL, ip);
-#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
-	if (!read)
-		atomic_long_set(&sem->rw_sem.owner, (long)current);
-#endif
 }
 
 #endif

include/linux/rcuwait.h

@@ -3,6 +3,7 @@
 #define _LINUX_RCUWAIT_H_
 
 #include <linux/rcupdate.h>
+#include <linux/sched/signal.h>
 
 /*
  * rcuwait provides a way of blocking and waking up a single
@@ -30,23 +31,30 @@ extern void rcuwait_wake_up(struct rcuwait *w);
  * The caller is responsible for locking around rcuwait_wait_event(),
  * such that writes to @task are properly serialized.
  */
-#define rcuwait_wait_event(w, condition)				\
+#define rcuwait_wait_event(w, condition, state)				\
 ({									\
+	int __ret = 0;							\
 	rcu_assign_pointer((w)->task, current);				\
 	for (;;) {							\
 		/*							\
 		 * Implicit barrier (A) pairs with (B) in		\
 		 * rcuwait_wake_up().					\
 		 */							\
-		set_current_state(TASK_UNINTERRUPTIBLE);		\
+		set_current_state(state);				\
 		if (condition)						\
 			break;						\
 									\
+		if (signal_pending_state(state, current)) {		\
+			__ret = -EINTR;					\
+			break;						\
+		}							\
+									\
 		schedule();						\
 	}								\
 									\
 	WRITE_ONCE((w)->task, NULL);					\
 	__set_current_state(TASK_RUNNING);				\
+	__ret;								\
 })
 
 #endif /* _LINUX_RCUWAIT_H_ */

include/linux/rwlock_types.h

@@ -22,7 +22,11 @@ typedef struct {
 #define RWLOCK_MAGIC		0xdeaf1eed
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define RW_DEP_MAP_INIT(lockname)	.dep_map = { .name = #lockname }
+# define RW_DEP_MAP_INIT(lockname)					\
+	.dep_map = {							\
+		.name = #lockname,					\
+		.wait_type_inner = LD_WAIT_CONFIG,			\
+	}
 #else
 # define RW_DEP_MAP_INIT(lockname)
 #endif

include/linux/rwsem.h

@@ -53,12 +53,6 @@ struct rw_semaphore {
 #endif
 };
 
-/*
- * Setting all bits of the owner field except bit 0 will indicate
- * that the rwsem is writer-owned with an unknown owner.
- */
-#define RWSEM_OWNER_UNKNOWN	(-2L)
-
 /* In all implementations count != 0 means locked */
 static inline int rwsem_is_locked(struct rw_semaphore *sem)
 {
@@ -71,7 +65,11 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
 /* Common initializer macros and functions */
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
+# define __RWSEM_DEP_MAP_INIT(lockname)			\
+	, .dep_map = {					\
+		.name = #lockname,			\
+		.wait_type_inner = LD_WAIT_SLEEP,	\
+	}
 #else
 # define __RWSEM_DEP_MAP_INIT(lockname)
 #endif

include/linux/sched.h

@@ -970,6 +970,7 @@ struct task_struct {
 
 #ifdef CONFIG_TRACE_IRQFLAGS
 	unsigned int			irq_events;
+	unsigned int			hardirq_threaded;
 	unsigned long			hardirq_enable_ip;
 	unsigned long			hardirq_disable_ip;
 	unsigned int			hardirq_enable_event;
@@ -982,6 +983,7 @@ struct task_struct {
 	unsigned int			softirq_enable_event;
 	int				softirqs_enabled;
 	int				softirq_context;
+	int				irq_config;
 #endif
 
 #ifdef CONFIG_LOCKDEP

include/linux/spinlock.h

@@ -93,12 +93,13 @@
 
 #ifdef CONFIG_DEBUG_SPINLOCK
   extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
-				   struct lock_class_key *key);
+				   struct lock_class_key *key, short inner);
-# define raw_spin_lock_init(lock)				\
+
-do {								\
+# define raw_spin_lock_init(lock)					\
-	static struct lock_class_key __key;			\
+do {									\
-								\
+	static struct lock_class_key __key;				\
-	__raw_spin_lock_init((lock), #lock, &__key);		\
+									\
+	__raw_spin_lock_init((lock), #lock, &__key, LD_WAIT_SPIN);	\
 } while (0)
 
 #else
@@ -327,12 +328,26 @@ static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
 	return &lock->rlock;
 }
 
-#define spin_lock_init(_lock)				\
+#ifdef CONFIG_DEBUG_SPINLOCK
-do {							\
+
-	spinlock_check(_lock);				\
+# define spin_lock_init(lock)					\
-	raw_spin_lock_init(&(_lock)->rlock);		\
+do {								\
+	static struct lock_class_key __key;			\
+								\
+	__raw_spin_lock_init(spinlock_check(lock),		\
+			     #lock, &__key, LD_WAIT_CONFIG);	\
 } while (0)
 
+#else
+
+# define spin_lock_init(_lock)			\
+do {						\
+	spinlock_check(_lock);			\
+	*(_lock) = __SPIN_LOCK_UNLOCKED(_lock);	\
+} while (0)
+
+#endif
+
 static __always_inline void spin_lock(spinlock_t *lock)
 {
 	raw_spin_lock(&lock->rlock);

include/linux/spinlock_types.h

@@ -33,8 +33,18 @@ typedef struct raw_spinlock {
 #define SPINLOCK_OWNER_INIT	((void *)-1L)
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define SPIN_DEP_MAP_INIT(lockname)	.dep_map = { .name = #lockname }
+# define RAW_SPIN_DEP_MAP_INIT(lockname)		\
+	.dep_map = {					\
+		.name = #lockname,			\
+		.wait_type_inner = LD_WAIT_SPIN,	\
+	}
+# define SPIN_DEP_MAP_INIT(lockname)			\
+	.dep_map = {					\
+		.name = #lockname,			\
+		.wait_type_inner = LD_WAIT_CONFIG,	\
+	}
 #else
+# define RAW_SPIN_DEP_MAP_INIT(lockname)
 # define SPIN_DEP_MAP_INIT(lockname)
 #endif
 
@@ -51,7 +61,7 @@ typedef struct raw_spinlock {
 	{					\
 	.raw_lock = __ARCH_SPIN_LOCK_UNLOCKED,	\
 	SPIN_DEBUG_INIT(lockname)		\
-	SPIN_DEP_MAP_INIT(lockname) }
+	RAW_SPIN_DEP_MAP_INIT(lockname) }
 
 #define __RAW_SPIN_LOCK_UNLOCKED(lockname)	\
 	(raw_spinlock_t) __RAW_SPIN_LOCK_INITIALIZER(lockname)
@@ -72,11 +82,17 @@ typedef struct spinlock {
 	};
 } spinlock_t;
 
+#define ___SPIN_LOCK_INITIALIZER(lockname)	\
+	{					\
+	.raw_lock = __ARCH_SPIN_LOCK_UNLOCKED,	\
+	SPIN_DEBUG_INIT(lockname)		\
+	SPIN_DEP_MAP_INIT(lockname) }
+
 #define __SPIN_LOCK_INITIALIZER(lockname) \
-	{ { .rlock = __RAW_SPIN_LOCK_INITIALIZER(lockname) } }
+	{ { .rlock = ___SPIN_LOCK_INITIALIZER(lockname) } }
 
 #define __SPIN_LOCK_UNLOCKED(lockname) \
-	(spinlock_t ) __SPIN_LOCK_INITIALIZER(lockname)
+	(spinlock_t) __SPIN_LOCK_INITIALIZER(lockname)
 
 #define DEFINE_SPINLOCK(x)	spinlock_t x = __SPIN_LOCK_UNLOCKED(x)
 

include/linux/wait.h

@@ -20,6 +20,7 @@ int default_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int
 #define WQ_FLAG_EXCLUSIVE	0x01
 #define WQ_FLAG_WOKEN		0x02
 #define WQ_FLAG_BOOKMARK	0x04
+#define WQ_FLAG_CUSTOM		0x08
 
 /*
  * A single wait-queue entry structure:

kernel/cpu.c

@@ -331,12 +331,12 @@ void lockdep_assert_cpus_held(void)
 
 static void lockdep_acquire_cpus_lock(void)
 {
-	rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
+	rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_);
 }
 
 static void lockdep_release_cpus_lock(void)
 {
-	rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, _THIS_IP_);
+	rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_);
 }
 
 /*

kernel/exit.c

@@ -258,6 +258,7 @@ void rcuwait_wake_up(struct rcuwait *w)
 		wake_up_process(task);
 	rcu_read_unlock();
 }
+EXPORT_SYMBOL_GPL(rcuwait_wake_up);
 
 /*
  * Determine if a process group is "orphaned", according to the POSIX

kernel/futex.c

@@ -135,8 +135,7 @@
  *
  * Where (A) orders the waiters increment and the futex value read through
  * atomic operations (see hb_waiters_inc) and where (B) orders the write
- * to futex and the waiters read -- this is done by the barriers for both
+ * to futex and the waiters read (see hb_waiters_pending()).
- * shared and private futexes in get_futex_key_refs().
  *
  * This yields the following case (where X:=waiters, Y:=futex):
  *
@@ -331,17 +330,6 @@ static void compat_exit_robust_list(struct task_struct *curr);
 static inline void compat_exit_robust_list(struct task_struct *curr) { }
 #endif
 
-static inline void futex_get_mm(union futex_key *key)
-{
-	mmgrab(key->private.mm);
-	/*
-	 * Ensure futex_get_mm() implies a full barrier such that
-	 * get_futex_key() implies a full barrier. This is relied upon
-	 * as smp_mb(); (B), see the ordering comment above.
-	 */
-	smp_mb__after_atomic();
-}
-
 /*
  * Reflects a new waiter being added to the waitqueue.
  */
@@ -370,6 +358,10 @@ static inline void hb_waiters_dec(struct futex_hash_bucket *hb)
 static inline int hb_waiters_pending(struct futex_hash_bucket *hb)
 {
 #ifdef CONFIG_SMP
+	/*
+	 * Full barrier (B), see the ordering comment above.
+	 */
+	smp_mb();
 	return atomic_read(&hb->waiters);
 #else
 	return 1;
@@ -407,69 +399,6 @@ static inline int match_futex(union futex_key *key1, union futex_key *key2)
 		&& key1->both.offset == key2->both.offset);
 }
 
-/*
- * Take a reference to the resource addressed by a key.
- * Can be called while holding spinlocks.
- *
- */
-static void get_futex_key_refs(union futex_key *key)
-{
-	if (!key->both.ptr)
-		return;
-
-	/*
-	 * On MMU less systems futexes are always "private" as there is no per
-	 * process address space. We need the smp wmb nevertheless - yes,
-	 * arch/blackfin has MMU less SMP ...
-	 */
-	if (!IS_ENABLED(CONFIG_MMU)) {
-		smp_mb(); /* explicit smp_mb(); (B) */
-		return;
-	}
-
-	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
-	case FUT_OFF_INODE:
-		smp_mb();		/* explicit smp_mb(); (B) */
-		break;
-	case FUT_OFF_MMSHARED:
-		futex_get_mm(key); /* implies smp_mb(); (B) */
-		break;
-	default:
-		/*
-		 * Private futexes do not hold reference on an inode or
-		 * mm, therefore the only purpose of calling get_futex_key_refs
-		 * is because we need the barrier for the lockless waiter check.
-		 */
-		smp_mb(); /* explicit smp_mb(); (B) */
-	}
-}
-
-/*
- * Drop a reference to the resource addressed by a key.
- * The hash bucket spinlock must not be held. This is
- * a no-op for private futexes, see comment in the get
- * counterpart.
- */
-static void drop_futex_key_refs(union futex_key *key)
-{
-	if (!key->both.ptr) {
-		/* If we're here then we tried to put a key we failed to get */
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	if (!IS_ENABLED(CONFIG_MMU))
-		return;
-
-	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
-	case FUT_OFF_INODE:
-		break;
-	case FUT_OFF_MMSHARED:
-		mmdrop(key->private.mm);
-		break;
-	}
-}
-
 enum futex_access {
 	FUTEX_READ,
 	FUTEX_WRITE
@@ -601,7 +530,6 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, enum futex_a
 	if (!fshared) {
 		key->private.mm = mm;
 		key->private.address = address;
-		get_futex_key_refs(key);  /* implies smp_mb(); (B) */
 		return 0;
 	}
 
@@ -741,8 +669,6 @@ again:
 		rcu_read_unlock();
 	}
 
-	get_futex_key_refs(key); /* implies smp_mb(); (B) */
-
 out:
 	put_page(page);
 	return err;
@@ -750,7 +676,6 @@ out:
 
 static inline void put_futex_key(union futex_key *key)
 {
-	drop_futex_key_refs(key);
 }
 
 /**
@@ -1740,10 +1665,9 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
 		oparg = 1 << oparg;
 	}
 
-	if (!access_ok(uaddr, sizeof(u32)))
+	pagefault_disable();
-		return -EFAULT;
-
 	ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr);
+	pagefault_enable();
 	if (ret)
 		return ret;
 
@@ -1885,7 +1809,6 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
 		plist_add(&q->list, &hb2->chain);
 		q->lock_ptr = &hb2->lock;
 	}
-	get_futex_key_refs(key2);
 	q->key = *key2;
 }
 
@@ -1907,7 +1830,6 @@ static inline
 void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
 			   struct futex_hash_bucket *hb)
 {
-	get_futex_key_refs(key);
 	q->key = *key;
 
 	__unqueue_futex(q);
@@ -2018,7 +1940,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
 			 u32 *cmpval, int requeue_pi)
 {
 	union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
-	int drop_count = 0, task_count = 0, ret;
+	int task_count = 0, ret;
 	struct futex_pi_state *pi_state = NULL;
 	struct futex_hash_bucket *hb1, *hb2;
 	struct futex_q *this, *next;
@@ -2139,7 +2061,6 @@ retry_private:
 		 */
 		if (ret > 0) {
 			WARN_ON(pi_state);
-			drop_count++;
 			task_count++;
 			/*
 			 * If we acquired the lock, then the user space value
@@ -2259,7 +2180,6 @@ retry_private:
 				 * doing so.
 				 */
 				requeue_pi_wake_futex(this, &key2, hb2);
-				drop_count++;
 				continue;
 			} else if (ret) {
 				/*
@@ -2280,7 +2200,6 @@ retry_private:
 			}
 		}
 		requeue_futex(this, hb1, hb2, &key2);
-		drop_count++;
 	}
 
 	/*
@@ -2295,15 +2214,6 @@ out_unlock:
 	wake_up_q(&wake_q);
 	hb_waiters_dec(hb2);
 
-	/*
-	 * drop_futex_key_refs() must be called outside the spinlocks. During
-	 * the requeue we moved futex_q's from the hash bucket at key1 to the
-	 * one at key2 and updated their key pointer.  We no longer need to
-	 * hold the references to key1.
-	 */
-	while (--drop_count >= 0)
-		drop_futex_key_refs(&key1);
-
 out_put_keys:
 	put_futex_key(&key2);
 out_put_key1:
@@ -2433,7 +2343,6 @@ retry:
 		ret = 1;
 	}
 
-	drop_futex_key_refs(&q->key);
 	return ret;
 }
 

kernel/irq/handle.c

@@ -145,6 +145,13 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags
 	for_each_action_of_desc(desc, action) {
 		irqreturn_t res;
 
+		/*
+		 * If this IRQ would be threaded under force_irqthreads, mark it so.
+		 */
+		if (irq_settings_can_thread(desc) &&
+		    !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
+			trace_hardirq_threaded();
+
 		trace_irq_handler_entry(irq, action);
 		res = action->handler(irq, action->dev_id);
 		trace_irq_handler_exit(irq, action, res);

kernel/irq_work.c

@@ -153,7 +153,9 @@ static void irq_work_run_list(struct llist_head *list)
 		 */
 		flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
 
+		lockdep_irq_work_enter(work);
 		work->func(work);
+		lockdep_irq_work_exit(work);
 		/*
 		 * Clear the BUSY bit and return to the free state if
 		 * no-one else claimed it meanwhile.

kernel/locking/lockdep_internals.h

@@ -106,6 +106,12 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
 #define STACK_TRACE_HASH_SIZE	16384
 #endif
 
+/*
+ * Bit definitions for lock_chain.irq_context
+ */
+#define LOCK_CHAIN_SOFTIRQ_CONTEXT	(1 << 0)
+#define LOCK_CHAIN_HARDIRQ_CONTEXT	(1 << 1)
+
 #define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
 
 #define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
@@ -124,17 +130,21 @@ extern const char *__get_key_name(const struct lockdep_subclass_key *key,
 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i);
 
 extern unsigned long nr_lock_classes;
+extern unsigned long nr_zapped_classes;
+extern unsigned long nr_zapped_lock_chains;
 extern unsigned long nr_list_entries;
 long lockdep_next_lockchain(long i);
 unsigned long lock_chain_count(void);
-extern int nr_chain_hlocks;
 extern unsigned long nr_stack_trace_entries;
 
 extern unsigned int nr_hardirq_chains;
 extern unsigned int nr_softirq_chains;
 extern unsigned int nr_process_chains;
-extern unsigned int max_lockdep_depth;
+extern unsigned int nr_free_chain_hlocks;
+extern unsigned int nr_lost_chain_hlocks;
+extern unsigned int nr_large_chain_blocks;
 
+extern unsigned int max_lockdep_depth;
 extern unsigned int max_bfs_queue_depth;
 
 #ifdef CONFIG_PROVE_LOCKING

kernel/locking/lockdep_proc.c

@@ -128,15 +128,22 @@ static int lc_show(struct seq_file *m, void *v)
 	struct lock_chain *chain = v;
 	struct lock_class *class;
 	int i;
+	static const char * const irq_strs[] = {
+		[0]			     = "0",
+		[LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq",
+		[LOCK_CHAIN_SOFTIRQ_CONTEXT] = "softirq",
+		[LOCK_CHAIN_SOFTIRQ_CONTEXT|
+		 LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq|softirq",
+	};
 
 	if (v == SEQ_START_TOKEN) {
-		if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
+		if (!nr_free_chain_hlocks)
 			seq_printf(m, "(buggered) ");
 		seq_printf(m, "all lock chains:\n");
 		return 0;
 	}
 
-	seq_printf(m, "irq_context: %d\n", chain->irq_context);
+	seq_printf(m, "irq_context: %s\n", irq_strs[chain->irq_context]);
 
 	for (i = 0; i < chain->depth; i++) {
 		class = lock_chain_get_class(chain, i);
@@ -271,8 +278,12 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
 #ifdef CONFIG_PROVE_LOCKING
 	seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 			lock_chain_count(), MAX_LOCKDEP_CHAINS);
-	seq_printf(m, " dependency chain hlocks:       %11d [max: %lu]\n",
+	seq_printf(m, " dependency chain hlocks used:  %11lu [max: %lu]\n",
-			nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
+			MAX_LOCKDEP_CHAIN_HLOCKS -
+			(nr_free_chain_hlocks + nr_lost_chain_hlocks),
+			MAX_LOCKDEP_CHAIN_HLOCKS);
+	seq_printf(m, " dependency chain hlocks lost:  %11u\n",
+			nr_lost_chain_hlocks);
 #endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS
@@ -336,6 +347,18 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
 	seq_printf(m, " debug_locks:                   %11u\n",
 			debug_locks);
 
+	/*
+	 * Zappped classes and lockdep data buffers reuse statistics.
+	 */
+	seq_puts(m, "\n");
+	seq_printf(m, " zapped classes:                %11lu\n",
+			nr_zapped_classes);
+#ifdef CONFIG_PROVE_LOCKING
+	seq_printf(m, " zapped lock chains:            %11lu\n",
+			nr_zapped_lock_chains);
+	seq_printf(m, " large chain blocks:            %11u\n",
+			nr_large_chain_blocks);
+#endif
 	return 0;
 }
 

kernel/locking/mutex-debug.c

@@ -85,7 +85,7 @@ void debug_mutex_init(struct mutex *lock, const char *name,
 	 * Make sure we are not reinitializing a held lock:
 	 */
 	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
-	lockdep_init_map(&lock->dep_map, name, key, 0);
+	lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
 #endif
 	lock->magic = lock;
 }

kernel/locking/percpu-rwsem.c

@@ -1,27 +1,29 @@
 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/atomic.h>
-#include <linux/rwsem.h>
 #include <linux/percpu.h>
+#include <linux/wait.h>
 #include <linux/lockdep.h>
 #include <linux/percpu-rwsem.h>
 #include <linux/rcupdate.h>
 #include <linux/sched.h>
+#include <linux/sched/task.h>
 #include <linux/errno.h>
 
-#include "rwsem.h"
-
 int __percpu_init_rwsem(struct percpu_rw_semaphore *sem,
-			const char *name, struct lock_class_key *rwsem_key)
+			const char *name, struct lock_class_key *key)
 {
 	sem->read_count = alloc_percpu(int);
 	if (unlikely(!sem->read_count))
 		return -ENOMEM;
 
-	/* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */
 	rcu_sync_init(&sem->rss);
-	__init_rwsem(&sem->rw_sem, name, rwsem_key);
 	rcuwait_init(&sem->writer);
-	sem->readers_block = 0;
+	init_waitqueue_head(&sem->waiters);
+	atomic_set(&sem->block, 0);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	debug_check_no_locks_freed((void *)sem, sizeof(*sem));
+	lockdep_init_map(&sem->dep_map, name, key, 0);
+#endif
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__percpu_init_rwsem);
@@ -41,73 +43,139 @@ void percpu_free_rwsem(struct percpu_rw_semaphore *sem)
 }
 EXPORT_SYMBOL_GPL(percpu_free_rwsem);
 
-int __percpu_down_read(struct percpu_rw_semaphore *sem, int try)
+static bool __percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
 {
+	__this_cpu_inc(*sem->read_count);
+
 	/*
 	 * Due to having preemption disabled the decrement happens on
 	 * the same CPU as the increment, avoiding the
 	 * increment-on-one-CPU-and-decrement-on-another problem.
 	 *
-	 * If the reader misses the writer's assignment of readers_block, then
+	 * If the reader misses the writer's assignment of sem->block, then the
-	 * the writer is guaranteed to see the reader's increment.
+	 * writer is guaranteed to see the reader's increment.
 	 *
 	 * Conversely, any readers that increment their sem->read_count after
-	 * the writer looks are guaranteed to see the readers_block value,
+	 * the writer looks are guaranteed to see the sem->block value, which
-	 * which in turn means that they are guaranteed to immediately
+	 * in turn means that they are guaranteed to immediately decrement
-	 * decrement their sem->read_count, so that it doesn't matter that the
+	 * their sem->read_count, so that it doesn't matter that the writer
-	 * writer missed them.
+	 * missed them.
 	 */
 
 	smp_mb(); /* A matches D */
 
 	/*
-	 * If !readers_block the critical section starts here, matched by the
+	 * If !sem->block the critical section starts here, matched by the
 	 * release in percpu_up_write().
 	 */
-	if (likely(!smp_load_acquire(&sem->readers_block)))
+	if (likely(!atomic_read_acquire(&sem->block)))
-		return 1;
+		return true;
 
-	/*
-	 * Per the above comment; we still have preemption disabled and
-	 * will thus decrement on the same CPU as we incremented.
-	 */
-	__percpu_up_read(sem);
-
-	if (try)
-		return 0;
-
-	/*
-	 * We either call schedule() in the wait, or we'll fall through
-	 * and reschedule on the preempt_enable() in percpu_down_read().
-	 */
-	preempt_enable_no_resched();
-
-	/*
-	 * Avoid lockdep for the down/up_read() we already have them.
-	 */
-	__down_read(&sem->rw_sem);
-	this_cpu_inc(*sem->read_count);
-	__up_read(&sem->rw_sem);
-
-	preempt_disable();
-	return 1;
-}
-EXPORT_SYMBOL_GPL(__percpu_down_read);
-
-void __percpu_up_read(struct percpu_rw_semaphore *sem)
-{
-	smp_mb(); /* B matches C */
-	/*
-	 * In other words, if they see our decrement (presumably to aggregate
-	 * zero, as that is the only time it matters) they will also see our
-	 * critical section.
-	 */
 	__this_cpu_dec(*sem->read_count);
 
-	/* Prod writer to recheck readers_active */
+	/* Prod writer to re-evaluate readers_active_check() */
 	rcuwait_wake_up(&sem->writer);
+
+	return false;
 }
-EXPORT_SYMBOL_GPL(__percpu_up_read);
+
+static inline bool __percpu_down_write_trylock(struct percpu_rw_semaphore *sem)
+{
+	if (atomic_read(&sem->block))
+		return false;
+
+	return atomic_xchg(&sem->block, 1) == 0;
+}
+
+static bool __percpu_rwsem_trylock(struct percpu_rw_semaphore *sem, bool reader)
+{
+	if (reader) {
+		bool ret;
+
+		preempt_disable();
+		ret = __percpu_down_read_trylock(sem);
+		preempt_enable();
+
+		return ret;
+	}
+	return __percpu_down_write_trylock(sem);
+}
+
+/*
+ * The return value of wait_queue_entry::func means:
+ *
+ *  <0 - error, wakeup is terminated and the error is returned
+ *   0 - no wakeup, a next waiter is tried
+ *  >0 - woken, if EXCLUSIVE, counted towards @nr_exclusive.
+ *
+ * We use EXCLUSIVE for both readers and writers to preserve FIFO order,
+ * and play games with the return value to allow waking multiple readers.
+ *
+ * Specifically, we wake readers until we've woken a single writer, or until a
+ * trylock fails.
+ */
+static int percpu_rwsem_wake_function(struct wait_queue_entry *wq_entry,
+				      unsigned int mode, int wake_flags,
+				      void *key)
+{
+	struct task_struct *p = get_task_struct(wq_entry->private);
+	bool reader = wq_entry->flags & WQ_FLAG_CUSTOM;
+	struct percpu_rw_semaphore *sem = key;
+
+	/* concurrent against percpu_down_write(), can get stolen */
+	if (!__percpu_rwsem_trylock(sem, reader))
+		return 1;
+
+	list_del_init(&wq_entry->entry);
+	smp_store_release(&wq_entry->private, NULL);
+
+	wake_up_process(p);
+	put_task_struct(p);
+
+	return !reader; /* wake (readers until) 1 writer */
+}
+
+static void percpu_rwsem_wait(struct percpu_rw_semaphore *sem, bool reader)
+{
+	DEFINE_WAIT_FUNC(wq_entry, percpu_rwsem_wake_function);
+	bool wait;
+
+	spin_lock_irq(&sem->waiters.lock);
+	/*
+	 * Serialize against the wakeup in percpu_up_write(), if we fail
+	 * the trylock, the wakeup must see us on the list.
+	 */
+	wait = !__percpu_rwsem_trylock(sem, reader);
+	if (wait) {
+		wq_entry.flags |= WQ_FLAG_EXCLUSIVE | reader * WQ_FLAG_CUSTOM;
+		__add_wait_queue_entry_tail(&sem->waiters, &wq_entry);
+	}
+	spin_unlock_irq(&sem->waiters.lock);
+
+	while (wait) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!smp_load_acquire(&wq_entry.private))
+			break;
+		schedule();
+	}
+	__set_current_state(TASK_RUNNING);
+}
+
+bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
+{
+	if (__percpu_down_read_trylock(sem))
+		return true;
+
+	if (try)
+		return false;
+
+	preempt_enable();
+	percpu_rwsem_wait(sem, /* .reader = */ true);
+	preempt_disable();
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(__percpu_down_read);
 
 #define per_cpu_sum(var)						\
 ({									\
@@ -124,6 +192,8 @@ EXPORT_SYMBOL_GPL(__percpu_up_read);
  * zero.  If this sum is zero, then it is stable due to the fact that if any
  * newly arriving readers increment a given counter, they will immediately
  * decrement that same counter.
+ *
+ * Assumes sem->block is set.
  */
 static bool readers_active_check(struct percpu_rw_semaphore *sem)
 {
@@ -142,32 +212,36 @@ static bool readers_active_check(struct percpu_rw_semaphore *sem)
 
 void percpu_down_write(struct percpu_rw_semaphore *sem)
 {
+	might_sleep();
+	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+
 	/* Notify readers to take the slow path. */
 	rcu_sync_enter(&sem->rss);
 
-	down_write(&sem->rw_sem);
+	/*
+	 * Try set sem->block; this provides writer-writer exclusion.
+	 * Having sem->block set makes new readers block.
+	 */
+	if (!__percpu_down_write_trylock(sem))
+		percpu_rwsem_wait(sem, /* .reader = */ false);
+
+	/* smp_mb() implied by __percpu_down_write_trylock() on success -- D matches A */
 
 	/*
-	 * Notify new readers to block; up until now, and thus throughout the
+	 * If they don't see our store of sem->block, then we are guaranteed to
-	 * longish rcu_sync_enter() above, new readers could still come in.
+	 * see their sem->read_count increment, and therefore will wait for
-	 */
+	 * them.
-	WRITE_ONCE(sem->readers_block, 1);
-
-	smp_mb(); /* D matches A */
-
-	/*
-	 * If they don't see our writer of readers_block, then we are
-	 * guaranteed to see their sem->read_count increment, and therefore
-	 * will wait for them.
 	 */
 
-	/* Wait for all now active readers to complete. */
+	/* Wait for all active readers to complete. */
-	rcuwait_wait_event(&sem->writer, readers_active_check(sem));
+	rcuwait_wait_event(&sem->writer, readers_active_check(sem), TASK_UNINTERRUPTIBLE);
 }
 EXPORT_SYMBOL_GPL(percpu_down_write);
 
 void percpu_up_write(struct percpu_rw_semaphore *sem)
 {
+	rwsem_release(&sem->dep_map, _RET_IP_);
+
 	/*
 	 * Signal the writer is done, no fast path yet.
 	 *
@@ -178,12 +252,12 @@ void percpu_up_write(struct percpu_rw_semaphore *sem)
 	 * Therefore we force it through the slow path which guarantees an
 	 * acquire and thereby guarantees the critical section's consistency.
 	 */
-	smp_store_release(&sem->readers_block, 0);
+	atomic_set_release(&sem->block, 0);
 
 	/*
-	 * Release the write lock, this will allow readers back in the game.
+	 * Prod any pending reader/writer to make progress.
 	 */
-	up_write(&sem->rw_sem);
+	__wake_up(&sem->waiters, TASK_NORMAL, 1, sem);
 
 	/*
 	 * Once this completes (at least one RCU-sched grace period hence) the

kernel/locking/rwsem.c

@@ -28,7 +28,6 @@
 #include <linux/rwsem.h>
 #include <linux/atomic.h>
 
-#include "rwsem.h"
 #include "lock_events.h"
 
 /*
@@ -329,7 +328,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
 	 * Make sure we are not reinitializing a held semaphore:
 	 */
 	debug_check_no_locks_freed((void *)sem, sizeof(*sem));
-	lockdep_init_map(&sem->dep_map, name, key, 0);
+	lockdep_init_map_wait(&sem->dep_map, name, key, 0, LD_WAIT_SLEEP);
 #endif
 #ifdef CONFIG_DEBUG_RWSEMS
 	sem->magic = sem;
@@ -660,8 +659,6 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem,
 	unsigned long flags;
 	bool ret = true;
 
-	BUILD_BUG_ON(!(RWSEM_OWNER_UNKNOWN & RWSEM_NONSPINNABLE));
-
 	if (need_resched()) {
 		lockevent_inc(rwsem_opt_fail);
 		return false;
@@ -1338,7 +1335,7 @@ static struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
 /*
  * lock for reading
  */
-inline void __down_read(struct rw_semaphore *sem)
+static inline void __down_read(struct rw_semaphore *sem)
 {
 	if (!rwsem_read_trylock(sem)) {
 		rwsem_down_read_slowpath(sem, TASK_UNINTERRUPTIBLE);
@@ -1426,7 +1423,7 @@ static inline int __down_write_trylock(struct rw_semaphore *sem)
 /*
  * unlock after reading
  */
-inline void __up_read(struct rw_semaphore *sem)
+static inline void __up_read(struct rw_semaphore *sem)
 {
 	long tmp;
 

kernel/locking/rwsem.h

@@ -1,10 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-
-#ifndef __INTERNAL_RWSEM_H
-#define __INTERNAL_RWSEM_H
-#include <linux/rwsem.h>
-
-extern void __down_read(struct rw_semaphore *sem);
-extern void __up_read(struct rw_semaphore *sem);
-
-#endif /* __INTERNAL_RWSEM_H */

kernel/locking/spinlock_debug.c

@@ -14,14 +14,14 @@
 #include <linux/export.h>
 
 void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
-			  struct lock_class_key *key)
+			  struct lock_class_key *key, short inner)
 {
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	/*
 	 * Make sure we are not reinitializing a held lock:
 	 */
 	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
-	lockdep_init_map(&lock->dep_map, name, key, 0);
+	lockdep_init_map_wait(&lock->dep_map, name, key, 0, inner);
 #endif
 	lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 	lock->magic = SPINLOCK_MAGIC;
@@ -39,7 +39,7 @@ void __rwlock_init(rwlock_t *lock, const char *name,
 	 * Make sure we are not reinitializing a held lock:
 	 */
 	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
-	lockdep_init_map(&lock->dep_map, name, key, 0);
+	lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_CONFIG);
 #endif
 	lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
 	lock->magic = RWLOCK_MAGIC;

kernel/rcu/tree.c

@@ -1124,6 +1124,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 		    !rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq &&
 		    (rnp->ffmask & rdp->grpmask)) {
 			init_irq_work(&rdp->rcu_iw, rcu_iw_handler);
+			atomic_set(&rdp->rcu_iw.flags, IRQ_WORK_HARD_IRQ);
 			rdp->rcu_iw_pending = true;
 			rdp->rcu_iw_gp_seq = rnp->gp_seq;
 			irq_work_queue_on(&rdp->rcu_iw, rdp->cpu);

kernel/rcu/update.c

@@ -239,18 +239,30 @@ core_initcall(rcu_set_runtime_mode);
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key rcu_lock_key;
-struct lockdep_map rcu_lock_map =
+struct lockdep_map rcu_lock_map = {
-	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
+	.name = "rcu_read_lock",
+	.key = &rcu_lock_key,
+	.wait_type_outer = LD_WAIT_FREE,
+	.wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */
+};
 EXPORT_SYMBOL_GPL(rcu_lock_map);
 
 static struct lock_class_key rcu_bh_lock_key;
-struct lockdep_map rcu_bh_lock_map =
+struct lockdep_map rcu_bh_lock_map = {
-	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
+	.name = "rcu_read_lock_bh",
+	.key = &rcu_bh_lock_key,
+	.wait_type_outer = LD_WAIT_FREE,
+	.wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */
+};
 EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
 
 static struct lock_class_key rcu_sched_lock_key;
-struct lockdep_map rcu_sched_lock_map =
+struct lockdep_map rcu_sched_lock_map = {
-	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
+	.name = "rcu_read_lock_sched",
+	.key = &rcu_sched_lock_key,
+	.wait_type_outer = LD_WAIT_FREE,
+	.wait_type_inner = LD_WAIT_SPIN,
+};
 EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
 
 static struct lock_class_key rcu_callback_key;

kernel/sched/completion.c

@@ -29,12 +29,12 @@ void complete(struct completion *x)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 
 	if (x->done != UINT_MAX)
 		x->done++;
-	__wake_up_locked(&x->wait, TASK_NORMAL, 1);
+	swake_up_locked(&x->wait);
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 }
 EXPORT_SYMBOL(complete);
 
@@ -58,10 +58,12 @@ void complete_all(struct completion *x)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	lockdep_assert_RT_in_threaded_ctx();
+
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 	x->done = UINT_MAX;
-	__wake_up_locked(&x->wait, TASK_NORMAL, 0);
+	swake_up_all_locked(&x->wait);
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 }
 EXPORT_SYMBOL(complete_all);
 
@@ -70,20 +72,20 @@ do_wait_for_common(struct completion *x,
 		   long (*action)(long), long timeout, int state)
 {
 	if (!x->done) {
-		DECLARE_WAITQUEUE(wait, current);
+		DECLARE_SWAITQUEUE(wait);
 
-		__add_wait_queue_entry_tail_exclusive(&x->wait, &wait);
 		do {
 			if (signal_pending_state(state, current)) {
 				timeout = -ERESTARTSYS;
 				break;
 			}
+			__prepare_to_swait(&x->wait, &wait);
 			__set_current_state(state);
-			spin_unlock_irq(&x->wait.lock);
+			raw_spin_unlock_irq(&x->wait.lock);
 			timeout = action(timeout);
-			spin_lock_irq(&x->wait.lock);
+			raw_spin_lock_irq(&x->wait.lock);
 		} while (!x->done && timeout);
-		__remove_wait_queue(&x->wait, &wait);
+		__finish_swait(&x->wait, &wait);
 		if (!x->done)
 			return timeout;
 	}
@@ -100,9 +102,9 @@ __wait_for_common(struct completion *x,
 
 	complete_acquire(x);
 
-	spin_lock_irq(&x->wait.lock);
+	raw_spin_lock_irq(&x->wait.lock);
 	timeout = do_wait_for_common(x, action, timeout, state);
-	spin_unlock_irq(&x->wait.lock);
+	raw_spin_unlock_irq(&x->wait.lock);
 
 	complete_release(x);
 
@@ -291,12 +293,12 @@ bool try_wait_for_completion(struct completion *x)
 	if (!READ_ONCE(x->done))
 		return false;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 	if (!x->done)
 		ret = false;
 	else if (x->done != UINT_MAX)
 		x->done--;
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(try_wait_for_completion);
@@ -322,8 +324,8 @@ bool completion_done(struct completion *x)
 	 * otherwise we can end up freeing the completion before complete()
 	 * is done referencing it.
 	 */
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 	return true;
 }
 EXPORT_SYMBOL(completion_done);

kernel/sched/sched.h

@@ -2492,3 +2492,6 @@ static inline bool is_per_cpu_kthread(struct task_struct *p)
 	return true;
 }
 #endif
+
+void swake_up_all_locked(struct swait_queue_head *q);
+void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait);

kernel/sched/swait.c

@@ -32,6 +32,19 @@ void swake_up_locked(struct swait_queue_head *q)
 }
 EXPORT_SYMBOL(swake_up_locked);
 
+/*
+ * Wake up all waiters. This is an interface which is solely exposed for
+ * completions and not for general usage.
+ *
+ * It is intentionally different from swake_up_all() to allow usage from
+ * hard interrupt context and interrupt disabled regions.
+ */
+void swake_up_all_locked(struct swait_queue_head *q)
+{
+	while (!list_empty(&q->task_list))
+		swake_up_locked(q);
+}
+
 void swake_up_one(struct swait_queue_head *q)
 {
 	unsigned long flags;
@@ -69,7 +82,7 @@ void swake_up_all(struct swait_queue_head *q)
 }
 EXPORT_SYMBOL(swake_up_all);
 
-static void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
+void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
 {
 	wait->task = current;
 	if (list_empty(&wait->task_list))

kernel/time/hrtimer.c

@@ -1404,7 +1404,7 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 	base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
 	base += hrtimer_clockid_to_base(clock_id);
 	timer->is_soft = softtimer;
-	timer->is_hard = !softtimer;
+	timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
 	timer->base = &cpu_base->clock_base[base];
 	timerqueue_init(&timer->node);
 }
@@ -1514,7 +1514,11 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
 	 */
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 	trace_hrtimer_expire_entry(timer, now);
+	lockdep_hrtimer_enter(timer);
+
 	restart = fn(timer);
+
+	lockdep_hrtimer_exit(timer);
 	trace_hrtimer_expire_exit(timer);
 	raw_spin_lock_irq(&cpu_base->lock);
 

kernel/time/jiffies.c

@@ -58,7 +58,8 @@ static struct clocksource clocksource_jiffies = {
 	.max_cycles	= 10,
 };
 
-__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
+__cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock);
+__cacheline_aligned_in_smp seqcount_t jiffies_seq;
 
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)
@@ -67,9 +68,9 @@ u64 get_jiffies_64(void)
 	u64 ret;
 
 	do {
-		seq = read_seqbegin(&jiffies_lock);
+		seq = read_seqcount_begin(&jiffies_seq);
 		ret = jiffies_64;
-	} while (read_seqretry(&jiffies_lock, seq));
+	} while (read_seqcount_retry(&jiffies_seq, seq));
 	return ret;
 }
 EXPORT_SYMBOL(get_jiffies_64);

kernel/time/posix-cpu-timers.c

@@ -1126,8 +1126,11 @@ void run_posix_cpu_timers(void)
 	if (!fastpath_timer_check(tsk))
 		return;
 
-	if (!lock_task_sighand(tsk, &flags))
+	lockdep_posixtimer_enter();
+	if (!lock_task_sighand(tsk, &flags)) {
+		lockdep_posixtimer_exit();
 		return;
+	}
 	/*
 	 * Here we take off tsk->signal->cpu_timers[N] and
 	 * tsk->cpu_timers[N] all the timers that are firing, and
@@ -1169,6 +1172,7 @@ void run_posix_cpu_timers(void)
 			cpu_timer_fire(timer);
 		spin_unlock(&timer->it_lock);
 	}
+	lockdep_posixtimer_exit();
 }
 
 /*

kernel/time/tick-common.c

@@ -84,13 +84,15 @@ int tick_is_oneshot_available(void)
 static void tick_periodic(int cpu)
 {
 	if (tick_do_timer_cpu == cpu) {
-		write_seqlock(&jiffies_lock);
+		raw_spin_lock(&jiffies_lock);
+		write_seqcount_begin(&jiffies_seq);
 
 		/* Keep track of the next tick event */
 		tick_next_period = ktime_add(tick_next_period, tick_period);
 
 		do_timer(1);
-		write_sequnlock(&jiffies_lock);
+		write_seqcount_end(&jiffies_seq);
+		raw_spin_unlock(&jiffies_lock);
 		update_wall_time();
 	}
 
@@ -162,9 +164,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
 		ktime_t next;
 
 		do {
-			seq = read_seqbegin(&jiffies_lock);
+			seq = read_seqcount_begin(&jiffies_seq);
 			next = tick_next_period;
-		} while (read_seqretry(&jiffies_lock, seq));
+		} while (read_seqcount_retry(&jiffies_seq, seq));
 
 		clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
 

kernel/time/tick-sched.c

@@ -65,7 +65,8 @@ static void tick_do_update_jiffies64(ktime_t now)
 		return;
 
 	/* Reevaluate with jiffies_lock held */
-	write_seqlock(&jiffies_lock);
+	raw_spin_lock(&jiffies_lock);
+	write_seqcount_begin(&jiffies_seq);
 
 	delta = ktime_sub(now, last_jiffies_update);
 	if (delta >= tick_period) {
@@ -91,10 +92,12 @@ static void tick_do_update_jiffies64(ktime_t now)
 		/* Keep the tick_next_period variable up to date */
 		tick_next_period = ktime_add(last_jiffies_update, tick_period);
 	} else {
-		write_sequnlock(&jiffies_lock);
+		write_seqcount_end(&jiffies_seq);
+		raw_spin_unlock(&jiffies_lock);
 		return;
 	}
-	write_sequnlock(&jiffies_lock);
+	write_seqcount_end(&jiffies_seq);
+	raw_spin_unlock(&jiffies_lock);
 	update_wall_time();
 }
 
@@ -105,12 +108,14 @@ static ktime_t tick_init_jiffy_update(void)
 {
 	ktime_t period;
 
-	write_seqlock(&jiffies_lock);
+	raw_spin_lock(&jiffies_lock);
+	write_seqcount_begin(&jiffies_seq);
 	/* Did we start the jiffies update yet ? */
 	if (last_jiffies_update == 0)
 		last_jiffies_update = tick_next_period;
 	period = last_jiffies_update;
-	write_sequnlock(&jiffies_lock);
+	write_seqcount_end(&jiffies_seq);
+	raw_spin_unlock(&jiffies_lock);
 	return period;
 }
 
@@ -240,6 +245,7 @@ static void nohz_full_kick_func(struct irq_work *work)
 
 static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {
 	.func = nohz_full_kick_func,
+	.flags = ATOMIC_INIT(IRQ_WORK_HARD_IRQ),
 };
 
 /*
@@ -676,10 +682,10 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
 
 	/* Read jiffies and the time when jiffies were updated last */
 	do {
-		seq = read_seqbegin(&jiffies_lock);
+		seq = read_seqcount_begin(&jiffies_seq);
 		basemono = last_jiffies_update;
 		basejiff = jiffies;
-	} while (read_seqretry(&jiffies_lock, seq));
+	} while (read_seqcount_retry(&jiffies_seq, seq));
 	ts->last_jiffies = basejiff;
 	ts->timer_expires_base = basemono;
 

kernel/time/timekeeping.c

@@ -2397,8 +2397,10 @@ EXPORT_SYMBOL(hardpps);
  */
 void xtime_update(unsigned long ticks)
 {
-	write_seqlock(&jiffies_lock);
+	raw_spin_lock(&jiffies_lock);
+	write_seqcount_begin(&jiffies_seq);
 	do_timer(ticks);
-	write_sequnlock(&jiffies_lock);
+	write_seqcount_end(&jiffies_seq);
+	raw_spin_unlock(&jiffies_lock);
 	update_wall_time();
 }

kernel/time/timekeeping.h

@@ -25,7 +25,8 @@ static inline void sched_clock_resume(void) { }
 extern void do_timer(unsigned long ticks);
 extern void update_wall_time(void);
 
-extern seqlock_t jiffies_lock;
+extern raw_spinlock_t jiffies_lock;
+extern seqcount_t jiffies_seq;
 
 #define CS_NAME_LEN	32
 

lib/Kconfig.debug

@@ -1086,6 +1086,23 @@ config PROVE_LOCKING
 
 	 For more details, see Documentation/locking/lockdep-design.rst.
 
+config PROVE_RAW_LOCK_NESTING
+	bool "Enable raw_spinlock - spinlock nesting checks"
+	depends on PROVE_LOCKING
+	default n
+	help
+	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
+	 that the lock nesting rules for PREEMPT_RT enabled kernels are
+	 not violated.
+
+	 NOTE: There are known nesting problems. So if you enable this
+	 option expect lockdep splats until these problems have been fully
+	 addressed which is work in progress. This config switch allows to
+	 identify and analyze these problems. It will be removed and the
+	 check permanentely enabled once the main issues have been fixed.
+
+	 If unsure, select N.
+
 config LOCK_STAT
 	bool "Lock usage statistics"
 	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

tools/objtool/check.c

@@ -488,6 +488,7 @@ static const char *uaccess_safe_builtin[] = {
 	"__sanitizer_cov_trace_cmp2",
 	"__sanitizer_cov_trace_cmp4",
 	"__sanitizer_cov_trace_cmp8",
+	"__sanitizer_cov_trace_switch",
 	/* UBSAN */
 	"ubsan_type_mismatch_common",
 	"__ubsan_handle_type_mismatch",