Boqun Feng 81121524f1 locking/rwbase: Take care of ordering guarantee for fastpath reader ... Readers of rwbase can lock and unlock without taking any inner lock, if that happens, we need the ordering provided by atomic operations to satisfy the ordering semantics of lock/unlock. Without that, considering the follow case: { X = 0 initially } CPU 0 CPU 1 ===== ===== rt_write_lock(); X = 1 rt_write_unlock(): atomic_add(READER_BIAS - WRITER_BIAS, ->readers); // ->readers is READER_BIAS. rt_read_lock(): if ((r = atomic_read(->readers)) < 0) // True atomic_try_cmpxchg(->readers, r, r + 1); // succeed. <acquire the read lock via fast path> r1 = X; // r1 may be 0, because nothing prevent the reordering // of "X=1" and atomic_add() on CPU 1. Therefore audit every usage of atomic operations that may happen in a fast path, and add necessary barriers. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20210909110203.953991276@infradead.org		2021-09-15 17:49:16 +02:00
..
irqflag-debug.c
lock_events.c
lock_events.h
lock_events_list.h
lockdep.c
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
locktorture.c
Makefile
mcs_spinlock.h
mutex-debug.c
mutex.c
mutex.h
osq_lock.c
percpu-rwsem.c
qrwlock.c
qspinlock.c
qspinlock_paravirt.h
qspinlock_stat.h
rtmutex.c	locking/rtmutex: Fix ww_mutex deadlock check	2021-09-09 10:31:22 +02:00
rtmutex_api.c
rtmutex_common.h
rwbase_rt.c	locking/rwbase: Take care of ordering guarantee for fastpath reader	2021-09-15 17:49:16 +02:00
rwsem.c	locking/rwsem: Add missing __init_rwsem() for PREEMPT_RT	2021-09-02 22:07:17 +02:00
semaphore.c
spinlock.c
spinlock_debug.c
spinlock_rt.c
test-ww_mutex.c
ww_mutex.h
ww_rt_mutex.c