[PATCH] spinlock consolidation

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>

2 files changed, 7 insertions, 15 deletions

diff --git a/arch/ppc64/lib/dec_and_lock.c b/arch/ppc64/lib/dec_and_lock.c
index 6e8d859..7b9d4da 100644
--- a/arch/ppc64/lib/dec_and_lock.c
+++ b/arch/ppc64/lib/dec_and_lock.c
@@ -20,14 +20,7 @@
  * has a cmpxchg, and where atomic->value is an int holding
  * the value of the atomic (i.e. the high bits aren't used
  * for a lock or anything like that).
- *
- * N.B. ATOMIC_DEC_AND_LOCK gets defined in include/linux/spinlock.h
- * if spinlocks are empty and thus atomic_dec_and_lock is defined
- * to be atomic_dec_and_test - in that case we don't need it
- * defined here as well.
  */
-
-#ifndef ATOMIC_DEC_AND_LOCK
 int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
 {
 	int counter;
@@ -52,4 +45,3 @@ int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
 }
 
 EXPORT_SYMBOL(_atomic_dec_and_lock);
-#endif /* ATOMIC_DEC_AND_LOCK */
diff --git a/arch/ppc64/lib/locks.c b/arch/ppc64/lib/locks.c
index ef70ef9..033643a 100644
--- a/arch/ppc64/lib/locks.c
+++ b/arch/ppc64/lib/locks.c
@@ -23,12 +23,12 @@
 /* waiting for a spinlock... */
 #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
 
-void __spin_yield(spinlock_t *lock)
+void __spin_yield(raw_spinlock_t *lock)
 {
 	unsigned int lock_value, holder_cpu, yield_count;
 	struct paca_struct *holder_paca;
 
-	lock_value = lock->lock;
+	lock_value = lock->slock;
 	if (lock_value == 0)
 		return;
 	holder_cpu = lock_value & 0xffff;
@@ -38,7 +38,7 @@ void __spin_yield(spinlock_t *lock)
 	if ((yield_count & 1) == 0)
 		return;		/* virtual cpu is currently running */
 	rmb();
-	if (lock->lock != lock_value)
+	if (lock->slock != lock_value)
 		return;		/* something has changed */
 #ifdef CONFIG_PPC_ISERIES
 	HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
@@ -54,7 +54,7 @@ void __spin_yield(spinlock_t *lock)
  * This turns out to be the same for read and write locks, since
  * we only know the holder if it is write-locked.
  */
-void __rw_yield(rwlock_t *rw)
+void __rw_yield(raw_rwlock_t *rw)
 {
 	int lock_value;
 	unsigned int holder_cpu, yield_count;
@@ -82,9 +82,9 @@ void __rw_yield(rwlock_t *rw)
 }
 #endif
 
-void spin_unlock_wait(spinlock_t *lock)
+void __raw_spin_unlock_wait(raw_spinlock_t *lock)
 {
-	while (lock->lock) {
+	while (lock->slock) {
 		HMT_low();
 		if (SHARED_PROCESSOR)
 			__spin_yield(lock);
@@ -92,4 +92,4 @@ void spin_unlock_wait(spinlock_t *lock)
 	HMT_medium();
 }
 
-EXPORT_SYMBOL(spin_unlock_wait);
+EXPORT_SYMBOL(__raw_spin_unlock_wait);