[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, 53 insertions, 97 deletions

diff --git a/include/asm-m32r/spinlock.h b/include/asm-m32r/spinlock.h
index 6608d8371c50..7de7def28da9 100644
--- a/include/asm-m32r/spinlock.h
+++ b/include/asm-m32r/spinlock.h
@@ -14,57 +14,30 @@
 #include <asm/atomic.h>
 #include <asm/page.h>
 
-extern int printk(const char * fmt, ...)
-	__attribute__ ((format (printf, 1, 2)));
-
-#define RW_LOCK_BIAS		 0x01000000
-#define RW_LOCK_BIAS_STR	"0x01000000"
-
 /*
  * Your basic SMP spinlocks, allowing only a single CPU anywhere
- */
-
-typedef struct {
-	volatile int slock;
-#ifdef CONFIG_DEBUG_SPINLOCK
-	unsigned magic;
-#endif
-#ifdef CONFIG_PREEMPT
-	unsigned int break_lock;
-#endif
-} spinlock_t;
-
-#define SPINLOCK_MAGIC	0xdead4ead
-
-#ifdef CONFIG_DEBUG_SPINLOCK
-#define SPINLOCK_MAGIC_INIT	, SPINLOCK_MAGIC
-#else
-#define SPINLOCK_MAGIC_INIT	/* */
-#endif
-
-#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT }
-
-#define spin_lock_init(x)	do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
-
-/*
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ *
  * Simple spin lock operations.  There are two variants, one clears IRQ's
  * on the local processor, one does not.
  *
  * We make no fairness assumptions. They have a cost.
  */
 
-#define spin_is_locked(x)	(*(volatile int *)(&(x)->slock) <= 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)		(*(volatile int *)(&(x)->slock) <= 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))
 
 /**
- * _raw_spin_trylock - Try spin lock and return a result
+ * __raw_spin_trylock - Try spin lock and return a result
  * @lock: Pointer to the lock variable
  *
- * _raw_spin_trylock() tries to get the lock and returns a result.
+ * __raw_spin_trylock() tries to get the lock and returns a result.
  * On the m32r, the result value is 1 (= Success) or 0 (= Failure).
  */
-static inline int _raw_spin_trylock(spinlock_t *lock)
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
 {
 	int oldval;
 	unsigned long tmp1, tmp2;
@@ -78,7 +51,7 @@ static inline int _raw_spin_trylock(spinlock_t *lock)
 	 * }
 	 */
 	__asm__ __volatile__ (
-		"# spin_trylock			\n\t"
+		"# __raw_spin_trylock		\n\t"
 		"ldi	%1, #0;			\n\t"
 		"mvfc	%2, psw;		\n\t"
 		"clrpsw	#0x40 -> nop;		\n\t"
@@ -97,16 +70,10 @@ static inline int _raw_spin_trylock(spinlock_t *lock)
 	return (oldval > 0);
 }
 
-static inline void _raw_spin_lock(spinlock_t *lock)
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
 {
 	unsigned long tmp0, tmp1;
 
-#ifdef CONFIG_DEBUG_SPINLOCK
-	if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
-		printk("pc: %p\n", __builtin_return_address(0));
-		BUG();
-	}
-#endif
 	/*
 	 * lock->slock :  =1 : unlock
 	 *             : <=0 : lock
@@ -118,7 +85,7 @@ static inline void _raw_spin_lock(spinlock_t *lock)
 	 * }
 	 */
 	__asm__ __volatile__ (
-		"# spin_lock			\n\t"
+		"# __raw_spin_lock		\n\t"
 		".fillinsn			\n"
 		"1:				\n\t"
 		"mvfc	%1, psw;		\n\t"
@@ -145,12 +112,8 @@ 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)
 {
-#ifdef CONFIG_DEBUG_SPINLOCK
-	BUG_ON(lock->magic != SPINLOCK_MAGIC);
-	BUG_ON(!spin_is_locked(lock));
-#endif
 	mb();
 	lock->slock = 1;
 }
@@ -164,59 +127,32 @@ static inline void _raw_spin_unlock(spinlock_t *lock)
  * can "mix" irq-safe locks - any writer needs to get a
  * irq-safe write-lock, but readers can get non-irqsafe
  * read-locks.
+ *
+ * On x86, we implement read-write locks as a 32-bit counter
+ * with the high bit (sign) being the "contended" bit.
+ *
+ * The inline assembly is non-obvious. Think about it.
+ *
+ * Changed to use the same technique as rw semaphores.  See
+ * semaphore.h for details.  -ben
  */
-typedef struct {
-	volatile int lock;
-#ifdef CONFIG_DEBUG_SPINLOCK
-	unsigned magic;
-#endif
-#ifdef CONFIG_PREEMPT
-	unsigned int break_lock;
-#endif
-} rwlock_t;
-
-#define RWLOCK_MAGIC	0xdeaf1eed
-
-#ifdef CONFIG_DEBUG_SPINLOCK
-#define RWLOCK_MAGIC_INIT	, RWLOCK_MAGIC
-#else
-#define RWLOCK_MAGIC_INIT	/* */
-#endif
-
-#define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT }
-
-#define rwlock_init(x)	do { *(x) = RW_LOCK_UNLOCKED; } while(0)
 
 /**
  * read_can_lock - would read_trylock() succeed?
  * @lock: the rwlock in question.
  */
-#define read_can_lock(x) ((int)(x)->lock > 0)
+#define __raw_read_can_lock(x) ((int)(x)->lock > 0)
 
 /**
  * write_can_lock - would write_trylock() succeed?
  * @lock: the rwlock in question.
  */
-#define write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
-
-/*
- * On x86, we implement read-write locks as a 32-bit counter
- * with the high bit (sign) being the "contended" bit.
- *
- * The inline assembly is non-obvious. Think about it.
- *
- * Changed to use the same technique as rw semaphores.  See
- * semaphore.h for details.  -ben
- */
-/* the spinlock helpers are in arch/i386/kernel/semaphore.c */
+#define __raw_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
 
-static inline void _raw_read_lock(rwlock_t *rw)
+static inline void __raw_read_lock(raw_rwlock_t *rw)
 {
 	unsigned long tmp0, tmp1;
 
-#ifdef CONFIG_DEBUG_SPINLOCK
-	BUG_ON(rw->magic != RWLOCK_MAGIC);
-#endif
 	/*
 	 * rw->lock :  >0 : unlock
 	 *          : <=0 : lock
@@ -264,13 +200,10 @@ static inline void _raw_read_lock(rwlock_t *rw)
 	);
 }
 
-static inline void _raw_write_lock(rwlock_t *rw)
+static inline void __raw_write_lock(raw_rwlock_t *rw)
 {
 	unsigned long tmp0, tmp1, tmp2;
 
-#ifdef CONFIG_DEBUG_SPINLOCK
-	BUG_ON(rw->magic != RWLOCK_MAGIC);
-#endif
 	/*
 	 * rw->lock :  =RW_LOCK_BIAS_STR : unlock
 	 *          : !=RW_LOCK_BIAS_STR : lock
@@ -320,7 +253,7 @@ static inline void _raw_write_lock(rwlock_t *rw)
 	);
 }
 
-static inline void _raw_read_unlock(rwlock_t *rw)
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
 {
 	unsigned long tmp0, tmp1;
 
@@ -342,7 +275,7 @@ static inline void _raw_read_unlock(rwlock_t *rw)
 	);
 }
 
-static inline void _raw_write_unlock(rwlock_t *rw)
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
 {
 	unsigned long tmp0, tmp1, tmp2;
 
@@ -366,9 +299,9 @@ static inline void _raw_write_unlock(rwlock_t *rw)
 	);
 }
 
-#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 *lock)
+static inline int __raw_write_trylock(raw_rwlock_t *lock)
 {
 	atomic_t *count = (atomic_t *)lock;
 	if (atomic_sub_and_test(RW_LOCK_BIAS, count))
diff --git a/include/asm-m32r/spinlock_types.h b/include/asm-m32r/spinlock_types.h
new file mode 100644
index 000000000000..7e9941c45f40
--- /dev/null
+++ b/include/asm-m32r/spinlock_types.h
@@ -0,0 +1,23 @@
+#ifndef _ASM_M32R_SPINLOCK_TYPES_H
+#define _ASM_M32R_SPINLOCK_TYPES_H
+
+#ifndef __LINUX_SPINLOCK_TYPES_H
+# error "please don't include this file directly"
+#endif
+
+typedef struct {
+	volatile int slock;
+} raw_spinlock_t;
+
+#define __RAW_SPIN_LOCK_UNLOCKED	{ 1 }
+
+typedef struct {
+	volatile int lock;
+} raw_rwlock_t;
+
+#define RW_LOCK_BIAS			0x01000000
+#define RW_LOCK_BIAS_STR		"0x01000000"
+
+#define __RAW_RW_LOCK_UNLOCKED		{ RW_LOCK_BIAS }
+
+#endif