[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, 47 insertions, 69 deletions

diff --git a/include/asm-alpha/spinlock.h b/include/asm-alpha/spinlock.h
index 80780db..8197c69 100644
--- a/include/asm-alpha/spinlock.h
+++ b/include/asm-alpha/spinlock.h
@@ -6,7 +6,6 @@
 #include <linux/kernel.h>
 #include <asm/current.h>
 
-
 /*
  * Simple spin lock operations.  There are two variants, one clears IRQ's
  * on the local processor, one does not.
@@ -14,43 +13,18 @@
  * We make no fairness assumptions. They have a cost.
  */
 
-typedef struct {
-	volatile unsigned int lock;
-#ifdef CONFIG_DEBUG_SPINLOCK
-	int on_cpu;
-	int line_no;
-	void *previous;
-	struct task_struct * task;
-	const char *base_file;
-#endif
-} spinlock_t;
-
-#ifdef CONFIG_DEBUG_SPINLOCK
-#define SPIN_LOCK_UNLOCKED	(spinlock_t){ 0, -1, 0, NULL, NULL, NULL }
-#else
-#define SPIN_LOCK_UNLOCKED	(spinlock_t){ 0 }
-#endif
-
-#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 ((x)->lock)
-
-#ifdef CONFIG_DEBUG_SPINLOCK
-extern void _raw_spin_unlock(spinlock_t * lock);
-extern void debug_spin_lock(spinlock_t * lock, const char *, int);
-extern int debug_spin_trylock(spinlock_t * lock, const char *, int);
-#define _raw_spin_lock(LOCK) \
-	debug_spin_lock(LOCK, __BASE_FILE__, __LINE__)
-#define _raw_spin_trylock(LOCK) \
-	debug_spin_trylock(LOCK, __BASE_FILE__, __LINE__)
-#else
-static inline void _raw_spin_unlock(spinlock_t * lock)
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+#define __raw_spin_is_locked(x)	((x)->lock != 0)
+#define __raw_spin_unlock_wait(x) \
+		do { cpu_relax(); } while ((x)->lock)
+
+static inline void __raw_spin_unlock(raw_spinlock_t * lock)
 {
 	mb();
 	lock->lock = 0;
 }
 
-static inline void _raw_spin_lock(spinlock_t * lock)
+static inline void __raw_spin_lock(raw_spinlock_t * lock)
 {
 	long tmp;
 
@@ -70,80 +44,64 @@ static inline void _raw_spin_lock(spinlock_t * lock)
 	: "m"(lock->lock) : "memory");
 }
 
-static inline int _raw_spin_trylock(spinlock_t *lock)
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
 {
 	return !test_and_set_bit(0, &lock->lock);
 }
-#endif /* CONFIG_DEBUG_SPINLOCK */
-
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 
 /***********************************************************/
 
-typedef struct {
-	volatile unsigned int lock;
-} rwlock_t;
-
-#define RW_LOCK_UNLOCKED	(rwlock_t){ 0 }
-
-#define rwlock_init(x)		do { *(x) = RW_LOCK_UNLOCKED; } while(0)
-
-static inline int read_can_lock(rwlock_t *lock)
+static inline int __raw_read_can_lock(raw_rwlock_t *lock)
 {
 	return (lock->lock & 1) == 0;
 }
 
-static inline int write_can_lock(rwlock_t *lock)
+static inline int __raw_write_can_lock(raw_rwlock_t *lock)
 {
 	return lock->lock == 0;
 }
 
-#ifdef CONFIG_DEBUG_RWLOCK
-extern void _raw_write_lock(rwlock_t * lock);
-extern void _raw_read_lock(rwlock_t * lock);
-#else
-static inline void _raw_write_lock(rwlock_t * lock)
+static inline void __raw_read_lock(raw_rwlock_t *lock)
 {
 	long regx;
 
 	__asm__ __volatile__(
 	"1:	ldl_l	%1,%0\n"
-	"	bne	%1,6f\n"
-	"	lda	%1,1\n"
+	"	blbs	%1,6f\n"
+	"	subl	%1,2,%1\n"
 	"	stl_c	%1,%0\n"
 	"	beq	%1,6f\n"
 	"	mb\n"
 	".subsection 2\n"
 	"6:	ldl	%1,%0\n"
-	"	bne	%1,6b\n"
+	"	blbs	%1,6b\n"
 	"	br	1b\n"
 	".previous"
 	: "=m" (*lock), "=&r" (regx)
 	: "m" (*lock) : "memory");
 }
 
-static inline void _raw_read_lock(rwlock_t * lock)
+static inline void __raw_write_lock(raw_rwlock_t *lock)
 {
 	long regx;
 
 	__asm__ __volatile__(
 	"1:	ldl_l	%1,%0\n"
-	"	blbs	%1,6f\n"
-	"	subl	%1,2,%1\n"
+	"	bne	%1,6f\n"
+	"	lda	%1,1\n"
 	"	stl_c	%1,%0\n"
 	"	beq	%1,6f\n"
 	"	mb\n"
 	".subsection 2\n"
 	"6:	ldl	%1,%0\n"
-	"	blbs	%1,6b\n"
+	"	bne	%1,6b\n"
 	"	br	1b\n"
 	".previous"
 	: "=m" (*lock), "=&r" (regx)
 	: "m" (*lock) : "memory");
 }
-#endif /* CONFIG_DEBUG_RWLOCK */
 
-static inline int _raw_read_trylock(rwlock_t * lock)
+static inline int __raw_read_trylock(raw_rwlock_t * lock)
 {
 	long regx;
 	int success;
@@ -165,7 +123,7 @@ static inline int _raw_read_trylock(rwlock_t * lock)
 	return success;
 }
 
-static inline int _raw_write_trylock(rwlock_t * lock)
+static inline int __raw_write_trylock(raw_rwlock_t * lock)
 {
 	long regx;
 	int success;
@@ -187,13 +145,7 @@ static inline int _raw_write_trylock(rwlock_t * lock)
 	return success;
 }
 
-static inline void _raw_write_unlock(rwlock_t * lock)
-{
-	mb();
-	lock->lock = 0;
-}
-
-static inline void _raw_read_unlock(rwlock_t * lock)
+static inline void __raw_read_unlock(raw_rwlock_t * lock)
 {
 	long regx;
 	__asm__ __volatile__(
@@ -209,4 +161,10 @@ static inline void _raw_read_unlock(rwlock_t * lock)
 	: "m" (*lock) : "memory");
 }
 
+static inline void __raw_write_unlock(raw_rwlock_t * lock)
+{
+	mb();
+	lock->lock = 0;
+}
+
 #endif /* _ALPHA_SPINLOCK_H */
diff --git a/include/asm-alpha/spinlock_types.h b/include/asm-alpha/spinlock_types.h
new file mode 100644
index 0000000..8141eb5
--- /dev/null
+++ b/include/asm-alpha/spinlock_types.h
@@ -0,0 +1,20 @@
+#ifndef _ALPHA_SPINLOCK_TYPES_H
+#define _ALPHA_SPINLOCK_TYPES_H
+
+#ifndef __LINUX_SPINLOCK_TYPES_H
+# error "please don't include this file directly"
+#endif
+
+typedef struct {
+	volatile unsigned int 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