Prepare for merging 32 and 64 bit spinlocks, by making them identical
(except for the OOSTORE thing). raw_read_lock and raw_write_lock get a
relaxed register constraint, and 64-bit has a few "=m" constraints changed
to "+m". I hope these things actually make the code better.
Signed-off-by: Nick Piggin <[email protected]>
---
Index: linux-2.6/include/asm-x86/spinlock_32.h
===================================================================
--- linux-2.6.orig/include/asm-x86/spinlock_32.h
+++ linux-2.6/include/asm-x86/spinlock_32.h
@@ -98,14 +98,15 @@ static inline int __raw_spin_trylock(raw
return ret;
}
-#if defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE)
+#if defined(CONFIG_X86_32) && \
+ (defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE))
/*
* On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock
* (PPro errata 66, 92)
*/
-#define UNLOCK_LOCK_PREFIX LOCK_PREFIX
+# define UNLOCK_LOCK_PREFIX LOCK_PREFIX
#else
-#define UNLOCK_LOCK_PREFIX
+# define UNLOCK_LOCK_PREFIX
#endif
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
@@ -135,49 +136,42 @@ static inline void __raw_spin_unlock_wai
*
* 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 helpers are in arch/i386/kernel/semaphore.c
*/
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
-static inline int __raw_read_can_lock(raw_rwlock_t *x)
+static inline int __raw_read_can_lock(raw_rwlock_t *lock)
{
- return (int)(x)->lock > 0;
+ return (int)(lock)->lock > 0;
}
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
-static inline int __raw_write_can_lock(raw_rwlock_t *x)
+static inline int __raw_write_can_lock(raw_rwlock_t *lock)
{
- return (x)->lock == RW_LOCK_BIAS;
+ return (lock)->lock == RW_LOCK_BIAS;
}
static inline void __raw_read_lock(raw_rwlock_t *rw)
{
- asm volatile(LOCK_PREFIX " subl $1,(%0)\n\t"
+ asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t"
"jns 1f\n"
"call __read_lock_failed\n\t"
"1:\n"
- ::"a" (rw) : "memory");
+ ::"r" (rw) : "memory");
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
- asm volatile(LOCK_PREFIX " subl $" RW_LOCK_BIAS_STR ",(%0)\n\t"
+ asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t"
"jz 1f\n"
"call __write_lock_failed\n\t"
"1:\n"
- ::"a" (rw) : "memory");
+ ::"r" (rw), "i" (RW_LOCK_BIAS) : "memory");
}
static inline int __raw_read_trylock(raw_rwlock_t *lock)
@@ -206,8 +200,8 @@ static inline void __raw_read_unlock(raw
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
- asm volatile(LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ", %0"
- : "+m" (rw->lock) : : "memory");
+ asm volatile(LOCK_PREFIX "addl %1,%0"
+ : "+m" (rw->lock) : "i" (RW_LOCK_BIAS) : "memory");
}
#define _raw_spin_relax(lock) cpu_relax()
Index: linux-2.6/include/asm-x86/spinlock_64.h
===================================================================
--- linux-2.6.orig/include/asm-x86/spinlock_64.h
+++ linux-2.6/include/asm-x86/spinlock_64.h
@@ -5,6 +5,7 @@
#include <asm/rwlock.h>
#include <asm/page.h>
#include <asm/processor.h>
+#include <linux/compiler.h>
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
@@ -126,11 +127,19 @@ static inline void __raw_spin_unlock_wai
* with the high bit (sign) being the "contended" bit.
*/
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
static inline int __raw_read_can_lock(raw_rwlock_t *lock)
{
return (int)(lock)->lock > 0;
}
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
static inline int __raw_write_can_lock(raw_rwlock_t *lock)
{
return (lock)->lock == RW_LOCK_BIAS;
@@ -140,18 +149,18 @@ static inline void __raw_read_lock(raw_r
{
asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t"
"jns 1f\n"
- "call __read_lock_failed\n"
+ "call __read_lock_failed\n\t"
"1:\n"
- ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
+ ::"r" (rw) : "memory");
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t"
"jz 1f\n"
- "\tcall __write_lock_failed\n\t"
+ "call __write_lock_failed\n\t"
"1:\n"
- ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
+ ::"r" (rw), "i" (RW_LOCK_BIAS) : "memory");
}
static inline int __raw_read_trylock(raw_rwlock_t *lock)
@@ -175,13 +184,13 @@ static inline int __raw_write_trylock(ra
static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
- asm volatile(LOCK_PREFIX " ; incl %0" :"=m" (rw->lock) : : "memory");
+ asm volatile(LOCK_PREFIX "incl %0" :"+m" (rw->lock) : : "memory");
}
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
- asm volatile(LOCK_PREFIX " ; addl $" RW_LOCK_BIAS_STR ",%0"
- : "=m" (rw->lock) : : "memory");
+ asm volatile(LOCK_PREFIX "addl %1,%0"
+ : "+m" (rw->lock) : "i" (RW_LOCK_BIAS) : "memory");
}
#define _raw_spin_relax(lock) cpu_relax()
-
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