[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, 20 insertions, 41 deletions

diff --git a/include/asm-sh/spinlock.h b/include/asm-sh/spinlock.h
index e770b55649eb..846322d4c35d 100644
--- a/include/asm-sh/spinlock.h
+++ b/include/asm-sh/spinlock.h
@@ -15,20 +15,11 @@
 /*
  * Your basic SMP spinlocks, allowing only a single CPU anywhere
  */
-typedef struct {
-        volatile unsigned long lock;
-#ifdef CONFIG_PREEMPT
-        unsigned int break_lock;
-#endif
-} spinlock_t;
 
-#define SPIN_LOCK_UNLOCKED      (spinlock_t) { 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_is_locked(x) ((x)->lock != 0)
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+#define __raw_spin_unlock_wait(x) \
+        do { cpu_relax(); } while (__raw_spin_is_locked(x))
 
 /*
  * Simple spin lock operations.  There are two variants, one clears IRQ's
@@ -36,7 +27,7 @@ typedef struct {
  *
  * We make no fairness assumptions.  They have a cost.
  */
-static inline void _raw_spin_lock(spinlock_t *lock)
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
 {
         __asm__ __volatile__ (
                 "1:\n\t"
@@ -49,14 +40,14 @@ static inline void _raw_spin_lock(spinlock_t *lock)
         );
 }
 
-static inline void _raw_spin_unlock(spinlock_t *lock)
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
 {
         assert_spin_locked(lock);
 
         lock->lock = 0;
 }
 
-#define _raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
+#define __raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
 
 /*
  * Read-write spinlocks, allowing multiple readers but only one writer.
@@ -66,51 +57,40 @@ static inline void _raw_spin_unlock(spinlock_t *lock)
  * needs to get a irq-safe write-lock, but readers can get non-irqsafe
  * read-locks.
  */
-typedef struct {
-        spinlock_t lock;
-        atomic_t counter;
-#ifdef CONFIG_PREEMPT
-        unsigned int break_lock;
-#endif
-} rwlock_t;
-
-#define RW_LOCK_BIAS            0x01000000
-#define RW_LOCK_UNLOCKED        (rwlock_t) { { 0 }, { RW_LOCK_BIAS } }
-#define rwlock_init(x)          do { *(x) = RW_LOCK_UNLOCKED; } while (0)
-
-static inline void _raw_read_lock(rwlock_t *rw)
+
+static inline void __raw_read_lock(raw_rwlock_t *rw)
 {
-        _raw_spin_lock(&rw->lock);
+        __raw_spin_lock(&rw->lock);
 
         atomic_inc(&rw->counter);
 
-        _raw_spin_unlock(&rw->lock);
+        __raw_spin_unlock(&rw->lock);
 }
 
-static inline void _raw_read_unlock(rwlock_t *rw)
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
 {
-        _raw_spin_lock(&rw->lock);
+        __raw_spin_lock(&rw->lock);
 
         atomic_dec(&rw->counter);
 
-        _raw_spin_unlock(&rw->lock);
+        __raw_spin_unlock(&rw->lock);
 }
 
-static inline void _raw_write_lock(rwlock_t *rw)
+static inline void __raw_write_lock(raw_rwlock_t *rw)
 {
-        _raw_spin_lock(&rw->lock);
+        __raw_spin_lock(&rw->lock);
         atomic_set(&rw->counter, -1);
 }
 
-static inline void _raw_write_unlock(rwlock_t *rw)
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
 {
         atomic_set(&rw->counter, 0);
-        _raw_spin_unlock(&rw->lock);
+        __raw_spin_unlock(&rw->lock);
 }
 
-#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
+#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
 
-static inline int _raw_write_trylock(rwlock_t *rw)
+static inline int __raw_write_trylock(raw_rwlock_t *rw)
 {
         if (atomic_sub_and_test(RW_LOCK_BIAS, &rw->counter))
                 return 1;
@@ -121,4 +101,3 @@ static inline int _raw_write_trylock(rwlock_t *rw)
 }
 
 #endif /* __ASM_SH_SPINLOCK_H */
-