[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, 41 insertions, 119 deletions

diff --git a/include/asm-sparc/spinlock.h b/include/asm-sparc/spinlock.h
index 0cbd87a..111727a 100644
--- a/include/asm-sparc/spinlock.h
+++ b/include/asm-sparc/spinlock.h
@@ -12,96 +12,12 @@
 
 #include <asm/psr.h>
 
-#ifdef CONFIG_DEBUG_SPINLOCK
-struct _spinlock_debug {
-	unsigned char lock;
-	unsigned long owner_pc;
-#ifdef CONFIG_PREEMPT
-	unsigned int break_lock;
-#endif
-};
-typedef struct _spinlock_debug spinlock_t;
-
-#define SPIN_LOCK_UNLOCKED	(spinlock_t) { 0, 0 }
-#define spin_lock_init(lp)	do { *(lp)= SPIN_LOCK_UNLOCKED; } while(0)
-#define spin_is_locked(lp)  (*((volatile unsigned char *)(&((lp)->lock))) != 0)
-#define spin_unlock_wait(lp)	do { barrier(); } while(*(volatile unsigned char *)(&(lp)->lock))
-
-extern void _do_spin_lock(spinlock_t *lock, char *str);
-extern int _spin_trylock(spinlock_t *lock);
-extern void _do_spin_unlock(spinlock_t *lock);
-
-#define _raw_spin_trylock(lp)	_spin_trylock(lp)
-#define _raw_spin_lock(lock)	_do_spin_lock(lock, "spin_lock")
-#define _raw_spin_unlock(lock)	_do_spin_unlock(lock)
-
-struct _rwlock_debug {
-	volatile unsigned int lock;
-	unsigned long owner_pc;
-	unsigned long reader_pc[NR_CPUS];
-#ifdef CONFIG_PREEMPT
-	unsigned int break_lock;
-#endif
-};
-typedef struct _rwlock_debug rwlock_t;
-
-#define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0, {0} }
-
-#define rwlock_init(lp)	do { *(lp)= RW_LOCK_UNLOCKED; } while(0)
-
-extern void _do_read_lock(rwlock_t *rw, char *str);
-extern void _do_read_unlock(rwlock_t *rw, char *str);
-extern void _do_write_lock(rwlock_t *rw, char *str);
-extern void _do_write_unlock(rwlock_t *rw);
-
-#define _raw_read_lock(lock)	\
-do {	unsigned long flags; \
-	local_irq_save(flags); \
-	_do_read_lock(lock, "read_lock"); \
-	local_irq_restore(flags); \
-} while(0)
-
-#define _raw_read_unlock(lock) \
-do {	unsigned long flags; \
-	local_irq_save(flags); \
-	_do_read_unlock(lock, "read_unlock"); \
-	local_irq_restore(flags); \
-} while(0)
-
-#define _raw_write_lock(lock) \
-do {	unsigned long flags; \
-	local_irq_save(flags); \
-	_do_write_lock(lock, "write_lock"); \
-	local_irq_restore(flags); \
-} while(0)
-
-#define _raw_write_unlock(lock) \
-do {	unsigned long flags; \
-	local_irq_save(flags); \
-	_do_write_unlock(lock); \
-	local_irq_restore(flags); \
-} while(0)
-
-#else /* !CONFIG_DEBUG_SPINLOCK */
-
-typedef struct {
-	unsigned char lock;
-#ifdef CONFIG_PREEMPT
-	unsigned int break_lock;
-#endif
-} spinlock_t;
-
-#define SPIN_LOCK_UNLOCKED	(spinlock_t) { 0 }
-
-#define spin_lock_init(lock)   (*((unsigned char *)(lock)) = 0)
-#define spin_is_locked(lock)    (*((volatile unsigned char *)(lock)) != 0)
+#define __raw_spin_is_locked(lock) (*((volatile unsigned char *)(lock)) != 0)
 
-#define spin_unlock_wait(lock) \
-do { \
-	barrier(); \
-} while(*((volatile unsigned char *)lock))
+#define __raw_spin_unlock_wait(lock) \
+	do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
 
-extern __inline__ void _raw_spin_lock(spinlock_t *lock)
+extern __inline__ void __raw_spin_lock(raw_spinlock_t *lock)
 {
 	__asm__ __volatile__(
 	"\n1:\n\t"
@@ -121,7 +37,7 @@ extern __inline__ void _raw_spin_lock(spinlock_t *lock)
 	: "g2", "memory", "cc");
 }
 
-extern __inline__ int _raw_spin_trylock(spinlock_t *lock)
+extern __inline__ int __raw_spin_trylock(raw_spinlock_t *lock)
 {
 	unsigned int result;
 	__asm__ __volatile__("ldstub [%1], %0"
@@ -131,7 +47,7 @@ extern __inline__ int _raw_spin_trylock(spinlock_t *lock)
 	return (result == 0);
 }
 
-extern __inline__ void _raw_spin_unlock(spinlock_t *lock)
+extern __inline__ void __raw_spin_unlock(raw_spinlock_t *lock)
 {
 	__asm__ __volatile__("stb %%g0, [%0]" : : "r" (lock) : "memory");
 }
@@ -147,23 +63,11 @@ extern __inline__ void _raw_spin_unlock(spinlock_t *lock)
  *
  * XXX This might create some problems with my dual spinlock
  * XXX scheme, deadlocks etc. -DaveM
- */
-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(lp)	do { *(lp)= RW_LOCK_UNLOCKED; } while(0)
-
-
-/* Sort of like atomic_t's on Sparc, but even more clever.
+ *
+ * Sort of like atomic_t's on Sparc, but even more clever.
  *
  *	------------------------------------
- *	| 24-bit counter           | wlock |  rwlock_t
+ *	| 24-bit counter           | wlock |  raw_rwlock_t
  *	------------------------------------
  *	 31                       8 7     0
  *
@@ -174,9 +78,9 @@ typedef struct {
  *
  * Unfortunately this scheme limits us to ~16,000,000 cpus.
  */
-extern __inline__ void _read_lock(rwlock_t *rw)
+extern __inline__ void __read_lock(raw_rwlock_t *rw)
 {
-	register rwlock_t *lp asm("g1");
+	register raw_rwlock_t *lp asm("g1");
 	lp = rw;
 	__asm__ __volatile__(
 	"mov	%%o7, %%g4\n\t"
@@ -187,16 +91,16 @@ extern __inline__ void _read_lock(rwlock_t *rw)
 	: "g2", "g4", "memory", "cc");
 }
 
-#define _raw_read_lock(lock) \
+#define __raw_read_lock(lock) \
 do {	unsigned long flags; \
 	local_irq_save(flags); \
-	_read_lock(lock); \
+	__raw_read_lock(lock); \
 	local_irq_restore(flags); \
 } while(0)
 
-extern __inline__ void _read_unlock(rwlock_t *rw)
+extern __inline__ void __read_unlock(raw_rwlock_t *rw)
 {
-	register rwlock_t *lp asm("g1");
+	register raw_rwlock_t *lp asm("g1");
 	lp = rw;
 	__asm__ __volatile__(
 	"mov	%%o7, %%g4\n\t"
@@ -207,16 +111,16 @@ extern __inline__ void _read_unlock(rwlock_t *rw)
 	: "g2", "g4", "memory", "cc");
 }
 
-#define _raw_read_unlock(lock) \
+#define __raw_read_unlock(lock) \
 do {	unsigned long flags; \
 	local_irq_save(flags); \
-	_read_unlock(lock); \
+	__raw_read_unlock(lock); \
 	local_irq_restore(flags); \
 } while(0)
 
-extern __inline__ void _raw_write_lock(rwlock_t *rw)
+extern __inline__ void __raw_write_lock(raw_rwlock_t *rw)
 {
-	register rwlock_t *lp asm("g1");
+	register raw_rwlock_t *lp asm("g1");
 	lp = rw;
 	__asm__ __volatile__(
 	"mov	%%o7, %%g4\n\t"
@@ -227,11 +131,9 @@ extern __inline__ void _raw_write_lock(rwlock_t *rw)
 	: "g2", "g4", "memory", "cc");
 }
 
-#define _raw_write_unlock(rw)	do { (rw)->lock = 0; } while(0)
-
-#endif /* CONFIG_DEBUG_SPINLOCK */
+#define __raw_write_unlock(rw)	do { (rw)->lock = 0; } while(0)
 
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
 
 #endif /* !(__ASSEMBLY__) */
 
diff --git a/include/asm-sparc/spinlock_types.h b/include/asm-sparc/spinlock_types.h
new file mode 100644
index 0000000..0a0fb11
--- /dev/null
+++ b/include/asm-sparc/spinlock_types.h
@@ -0,0 +1,20 @@
+#ifndef __SPARC_SPINLOCK_TYPES_H
+#define __SPARC_SPINLOCK_TYPES_H
+
+#ifndef __LINUX_SPINLOCK_TYPES_H
+# error "please don't include this file directly"
+#endif
+
+typedef struct {
+	unsigned char lock;
+} raw_spinlock_t;
+
+#define __RAW_SPIN_LOCK_UNLOCKED	{ 0 }
+
+typedef struct {
+	volatile unsigned int lock;
+} raw_rwlock_t;
+
+#define __RAW_RW_LOCK_UNLOCKED		{ 0 }
+
+#endif