[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>

1 files changed, 17 insertions, 33 deletions

diff --git a/include/asm-arm/spinlock.h b/include/asm-arm/spinlock.h
index 1f906d09b688..cb4906b45555 100644
--- a/include/asm-arm/spinlock.h
+++ b/include/asm-arm/spinlock.h
@@ -16,21 +16,14 @@
  * Unlocked value: 0
  * Locked value: 1
  */
-typedef struct {
-        volatile unsigned int lock;
-#ifdef CONFIG_PREEMPT
-        unsigned int break_lock;
-#endif
-} spinlock_t;
 
-#define SPIN_LOCK_UNLOCKED      (spinlock_t) { 0 }
+#define __raw_spin_is_locked(x)         ((x)->lock != 0)
+#define __raw_spin_unlock_wait(lock) \
+        do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
 
-#define spin_lock_init(x)       do { *(x) = SPIN_LOCK_UNLOCKED; } while (0)
-#define spin_is_locked(x)       ((x)->lock != 0)
-#define spin_unlock_wait(x)     do { barrier(); } while (spin_is_locked(x))
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
 
-static inline void _raw_spin_lock(spinlock_t *lock)
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
 {
         unsigned long tmp;
 
@@ -47,7 +40,7 @@ static inline void _raw_spin_lock(spinlock_t *lock)
         smp_mb();
 }
 
-static inline int _raw_spin_trylock(spinlock_t *lock)
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
 {
         unsigned long tmp;
 
@@ -67,7 +60,7 @@ static inline int _raw_spin_trylock(spinlock_t *lock)
         }
 }
 
-static inline void _raw_spin_unlock(spinlock_t *lock)
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
 {
         smp_mb();
 
@@ -80,23 +73,14 @@ static inline void _raw_spin_unlock(spinlock_t *lock)
 
 /*
  * RWLOCKS
- */
-typedef struct {
-        volatile unsigned int lock;
-#ifdef CONFIG_PREEMPT
-        unsigned int break_lock;
-#endif
-} rwlock_t;
-
-#define RW_LOCK_UNLOCKED        (rwlock_t) { 0 }
-#define rwlock_init(x)          do { *(x) = RW_LOCK_UNLOCKED; } while (0)
-#define rwlock_is_locked(x)     (*((volatile unsigned int *)(x)) != 0)
-
-/*
+ *
+ *
  * Write locks are easy - we just set bit 31.  When unlocking, we can
  * just write zero since the lock is exclusively held.
  */
-static inline void _raw_write_lock(rwlock_t *rw)
+#define rwlock_is_locked(x)     (*((volatile unsigned int *)(x)) != 0)
+
+static inline void __raw_write_lock(rwlock_t *rw)
 {
         unsigned long tmp;
 
@@ -113,7 +97,7 @@ static inline void _raw_write_lock(rwlock_t *rw)
         smp_mb();
 }
 
-static inline int _raw_write_trylock(rwlock_t *rw)
+static inline int __raw_write_trylock(rwlock_t *rw)
 {
         unsigned long tmp;
 
@@ -133,7 +117,7 @@ static inline int _raw_write_trylock(rwlock_t *rw)
         }
 }
 
-static inline void _raw_write_unlock(rwlock_t *rw)
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
 {
         smp_mb();
 
@@ -156,7 +140,7 @@ static inline void _raw_write_unlock(rwlock_t *rw)
  * currently active.  However, we know we won't have any write
  * locks.
  */
-static inline void _raw_read_lock(rwlock_t *rw)
+static inline void __raw_read_lock(raw_rwlock_t *rw)
 {
         unsigned long tmp, tmp2;
 
@@ -173,7 +157,7 @@ static inline void _raw_read_lock(rwlock_t *rw)
         smp_mb();
 }
 
-static inline void _raw_read_unlock(rwlock_t *rw)
+static inline void __raw_read_unlock(rwlock_t *rw)
 {
         unsigned long tmp, tmp2;
 
@@ -190,6 +174,6 @@ static inline void _raw_read_unlock(rwlock_t *rw)
         : "cc");
 }
 
-#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
+#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
 
 #endif /* __ASM_SPINLOCK_H */