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[PATCH] spinlock consolidation

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This patch (written by me and also containing many suggestions of Arjan van
de Ven) does a major cleanup of the spinlock code.  It does the following
things:

 - consolidates and enhances the spinlock/rwlock debugging code

 - simplifies the asm/spinlock.h files

 - encapsulates the raw spinlock type and moves generic spinlock
   features (such as ->break_lock) into the generic code.

 - cleans up the spinlock code hierarchy to get rid of the spaghetti.

Most notably there's now only a single variant of the debugging code,
located in lib/spinlock_debug.c.  (previously we had one SMP debugging
variant per architecture, plus a separate generic one for UP builds)

Also, i've enhanced the rwlock debugging facility, it will now track
write-owners.  There is new spinlock-owner/CPU-tracking on SMP builds too.
All locks have lockup detection now, which will work for both soft and hard
spin/rwlock lockups.

The arch-level include files now only contain the minimally necessary
subset of the spinlock code - all the rest that can be generalized now
lives in the generic headers:

 include/asm-i386/spinlock_types.h       |   16
 include/asm-x86_64/spinlock_types.h     |   16

I have also split up the various spinlock variants into separate files,
making it easier to see which does what. The new layout is:

   SMP                         |  UP
   ----------------------------|-----------------------------------
   asm/spinlock_types_smp.h    |  linux/spinlock_types_up.h
   linux/spinlock_types.h      |  linux/spinlock_types.h
   asm/spinlock_smp.h          |  linux/spinlock_up.h
   linux/spinlock_api_smp.h    |  linux/spinlock_api_up.h
   linux/spinlock.h            |  linux/spinlock.h

/*
 * here's the role of the various spinlock/rwlock related include files:
 *
 * on SMP builds:
 *
 *  asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
 *                        initializers
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  asm/spinlock.h:       contains the __raw_spin_*()/etc. lowlevel
 *                        implementations, mostly inline assembly code
 *
 *   (also included on UP-debug builds:)
 *
 *  linux/spinlock_api_smp.h:
 *                        contains the prototypes for the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 *
 * on UP builds:
 *
 *  linux/spinlock_type_up.h:
 *                        contains the generic, simplified UP spinlock type.
 *                        (which is an empty structure on non-debug builds)
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  linux/spinlock_up.h:
 *                        contains the __raw_spin_*()/etc. version of UP
 *                        builds. (which are NOPs on non-debug, non-preempt
 *                        builds)
 *
 *   (included on UP-non-debug builds:)
 *
 *  linux/spinlock_api_up.h:
 *                        builds the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 */

All SMP and UP architectures are converted by this patch.

arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via
crosscompilers.  m32r, mips, sh, sparc, have not been tested yet, but should
be mostly fine.

From: Grant Grundler <grundler@parisc-linux.org>

  Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU).
  Builds 32-bit SMP kernel (not booted or tested).  I did not try to build
  non-SMP kernels.  That should be trivial to fix up later if necessary.

  I converted bit ops atomic_hash lock to raw_spinlock_t.  Doing so avoids
  some ugly nesting of linux/*.h and asm/*.h files.  Those particular locks
  are well tested and contained entirely inside arch specific code.  I do NOT
  expect any new issues to arise with them.

 If someone does ever need to use debug/metrics with them, then they will
  need to unravel this hairball between spinlocks, atomic ops, and bit ops
  that exist only because parisc has exactly one atomic instruction: LDCW
  (load and clear word).

From: "Luck, Tony" <tony.luck@intel.com>

   ia64 fix

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjanv@infradead.org>
Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se>
Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2005-09-10 00:25:56 -07:00 • committed by Linus Torvalds
parent 4327edf6b8
commit fb1c8f93d8
69 changed files with 1617 additions and 2897 deletions
Download patch file Download diff file Expand all files Collapse all files

10
arch/sparc/kernel/sparc_ksyms.c
View file

@ -114,17 +114,7 @@ DOT_ALIAS2(unsigned, urem, unsigned, unsigned)
/* used by various drivers */
EXPORT_SYMBOL(sparc_cpu_model);
EXPORT_SYMBOL(kernel_thread);
#ifdef CONFIG_DEBUG_SPINLOCK
#ifdef CONFIG_SMP
EXPORT_SYMBOL(_do_spin_lock);
EXPORT_SYMBOL(_do_spin_unlock);
EXPORT_SYMBOL(_spin_trylock);
EXPORT_SYMBOL(_do_read_lock);
EXPORT_SYMBOL(_do_read_unlock);
EXPORT_SYMBOL(_do_write_lock);
EXPORT_SYMBOL(_do_write_unlock);
#endif
#else
// XXX find what uses (or used) these.
EXPORT_SYMBOL(___rw_read_enter);
EXPORT_SYMBOL(___rw_read_exit);

2
arch/sparc/lib/Makefile
View file

@ -9,5 +9,3 @@ lib-y := mul.o rem.o sdiv.o udiv.o umul.o urem.o ashrdi3.o memcpy.o memset.o \
strncpy_from_user.o divdi3.o udivdi3.o strlen_user.o \
copy_user.o locks.o atomic.o atomic32.o bitops.o \
lshrdi3.o ashldi3.o rwsem.o muldi3.o bitext.o
lib-$(CONFIG_DEBUG_SPINLOCK) += debuglocks.o

202
arch/sparc/lib/debuglocks.c
View file

@ -1,202 +0,0 @@
/* $Id: debuglocks.c,v 1.11 2001/09/20 00:35:31 davem Exp $
* debuglocks.c: Debugging versions of SMP locking primitives.
*
* Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1998-99 Anton Blanchard (anton@progsoc.uts.edu.au)
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/threads.h> /* For NR_CPUS */
#include <linux/spinlock.h>
#include <asm/psr.h>
#include <asm/system.h>
#ifdef CONFIG_SMP
/* Some notes on how these debugging routines work. When a lock is acquired
* an extra debugging member lock->owner_pc is set to the caller of the lock
* acquisition routine. Right before releasing a lock, the debugging program
* counter is cleared to zero.
*
* Furthermore, since PC's are 4 byte aligned on Sparc, we stuff the CPU
* number of the owner in the lowest two bits.
*/
#define STORE_CALLER(A) __asm__ __volatile__("mov %%i7, %0" : "=r" (A));
static inline void show(char *str, spinlock_t *lock, unsigned long caller)
{
int cpu = smp_processor_id();
printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)\n",str,
lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
}
static inline void show_read(char *str, rwlock_t *lock, unsigned long caller)
{
int cpu = smp_processor_id();
printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)\n", str,
lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
}
static inline void show_write(char *str, rwlock_t *lock, unsigned long caller)
{
int cpu = smp_processor_id();
int i;
printk("%s(%p) CPU#%d stuck at %08lx, owner PC(%08lx):CPU(%lx)", str,
lock, cpu, caller, lock->owner_pc & ~3, lock->owner_pc & 3);
for(i = 0; i < NR_CPUS; i++)
printk(" reader[%d]=%08lx", i, lock->reader_pc[i]);
printk("\n");
}
#undef INIT_STUCK
#define INIT_STUCK 100000000
void _do_spin_lock(spinlock_t *lock, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
again:
__asm__ __volatile__("ldstub [%1], %0" : "=r" (val) : "r" (&(lock->lock)));
if(val) {
while(lock->lock) {
if (!--stuck) {
show(str, lock, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto again;
}
lock->owner_pc = (cpu & 3) | (caller & ~3);
}
int _spin_trylock(spinlock_t *lock)
{
unsigned long val;
unsigned long caller;
int cpu = smp_processor_id();
STORE_CALLER(caller);
__asm__ __volatile__("ldstub [%1], %0" : "=r" (val) : "r" (&(lock->lock)));
if(!val) {
/* We got it, record our identity for debugging. */
lock->owner_pc = (cpu & 3) | (caller & ~3);
}
return val == 0;
}
void _do_spin_unlock(spinlock_t *lock)
{
lock->owner_pc = 0;
barrier();
lock->lock = 0;
}
void _do_read_lock(rwlock_t *rw, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
wlock_again:
__asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
if(val) {
while(rw->lock & 0xff) {
if (!--stuck) {
show_read(str, rw, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto wlock_again;
}
rw->reader_pc[cpu] = caller;
barrier();
rw->lock++;
}
void _do_read_unlock(rwlock_t *rw, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
wlock_again:
__asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
if(val) {
while(rw->lock & 0xff) {
if (!--stuck) {
show_read(str, rw, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto wlock_again;
}
rw->reader_pc[cpu] = 0;
barrier();
rw->lock -= 0x1ff;
}
void _do_write_lock(rwlock_t *rw, char *str)
{
unsigned long caller;
unsigned long val;
int cpu = smp_processor_id();
int stuck = INIT_STUCK;
STORE_CALLER(caller);
wlock_again:
__asm__ __volatile__("ldstub [%1 + 3], %0" : "=r" (val) : "r" (&(rw->lock)));
if(val) {
wlock_wait:
while(rw->lock) {
if (!--stuck) {
show_write(str, rw, caller);
stuck = INIT_STUCK;
}
barrier();
}
goto wlock_again;
}
if (rw->lock & ~0xff) {
*(((unsigned char *)&rw->lock)+3) = 0;
barrier();
goto wlock_wait;
}
barrier();
rw->owner_pc = (cpu & 3) | (caller & ~3);
}
void _do_write_unlock(rwlock_t *rw)
{
rw->owner_pc = 0;
barrier();
rw->lock = 0;
}
#endif /* SMP */