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Diffstat (limited to 'arch/x86/include/asm/rwsem.h')
-rw-r--r--arch/x86/include/asm/rwsem.h129
1 files changed, 36 insertions, 93 deletions
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index 606ede12697..cad82c9c2fd 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -37,26 +37,9 @@
#endif
#ifdef __KERNEL__
-
-#include <linux/list.h>
-#include <linux/spinlock.h>
-#include <linux/lockdep.h>
#include <asm/asm.h>
-struct rwsem_waiter;
-
-extern asmregparm struct rw_semaphore *
- rwsem_down_read_failed(struct rw_semaphore *sem);
-extern asmregparm struct rw_semaphore *
- rwsem_down_write_failed(struct rw_semaphore *sem);
-extern asmregparm struct rw_semaphore *
- rwsem_wake(struct rw_semaphore *);
-extern asmregparm struct rw_semaphore *
- rwsem_downgrade_wake(struct rw_semaphore *sem);
-
/*
- * the semaphore definition
- *
* The bias values and the counter type limits the number of
* potential readers/writers to 32767 for 32 bits and 2147483647
* for 64 bits.
@@ -74,43 +57,6 @@ extern asmregparm struct rw_semaphore *
#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
-typedef signed long rwsem_count_t;
-
-struct rw_semaphore {
- rwsem_count_t count;
- spinlock_t wait_lock;
- struct list_head wait_list;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- struct lockdep_map dep_map;
-#endif
-};
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
-#else
-# define __RWSEM_DEP_MAP_INIT(lockname)
-#endif
-
-
-#define __RWSEM_INITIALIZER(name) \
-{ \
- RWSEM_UNLOCKED_VALUE, __SPIN_LOCK_UNLOCKED((name).wait_lock), \
- LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) \
-}
-
-#define DECLARE_RWSEM(name) \
- struct rw_semaphore name = __RWSEM_INITIALIZER(name)
-
-extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
- struct lock_class_key *key);
-
-#define init_rwsem(sem) \
-do { \
- static struct lock_class_key __key; \
- \
- __init_rwsem((sem), #sem, &__key); \
-} while (0)
-
/*
* lock for reading
*/
@@ -118,7 +64,7 @@ static inline void __down_read(struct rw_semaphore *sem)
{
asm volatile("# beginning down_read\n\t"
LOCK_PREFIX _ASM_INC "(%1)\n\t"
- /* adds 0x00000001, returns the old value */
+ /* adds 0x00000001 */
" jns 1f\n"
" call call_rwsem_down_read_failed\n"
"1:\n\t"
@@ -133,7 +79,7 @@ static inline void __down_read(struct rw_semaphore *sem)
*/
static inline int __down_read_trylock(struct rw_semaphore *sem)
{
- rwsem_count_t result, tmp;
+ long result, tmp;
asm volatile("# beginning __down_read_trylock\n\t"
" mov %0,%1\n\t"
"1:\n\t"
@@ -155,20 +101,18 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
*/
static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
{
- rwsem_count_t tmp;
-
- tmp = RWSEM_ACTIVE_WRITE_BIAS;
+ long tmp;
asm volatile("# beginning down_write\n\t"
LOCK_PREFIX " xadd %1,(%2)\n\t"
- /* subtract 0x0000ffff, returns the old value */
- " test %1,%1\n\t"
- /* was the count 0 before? */
+ /* adds 0xffff0001, returns the old value */
+ " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t"
+ /* was the active mask 0 before? */
" jz 1f\n"
" call call_rwsem_down_write_failed\n"
"1:\n"
"# ending down_write"
: "+m" (sem->count), "=d" (tmp)
- : "a" (sem), "1" (tmp)
+ : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
: "memory", "cc");
}
@@ -182,12 +126,25 @@ static inline void __down_write(struct rw_semaphore *sem)
*/
static inline int __down_write_trylock(struct rw_semaphore *sem)
{
- rwsem_count_t ret = cmpxchg(&sem->count,
- RWSEM_UNLOCKED_VALUE,
- RWSEM_ACTIVE_WRITE_BIAS);
- if (ret == RWSEM_UNLOCKED_VALUE)
- return 1;
- return 0;
+ long result, tmp;
+ asm volatile("# beginning __down_write_trylock\n\t"
+ " mov %0,%1\n\t"
+ "1:\n\t"
+ " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t"
+ /* was the active mask 0 before? */
+ " jnz 2f\n\t"
+ " mov %1,%2\n\t"
+ " add %3,%2\n\t"
+ LOCK_PREFIX " cmpxchg %2,%0\n\t"
+ " jnz 1b\n\t"
+ "2:\n\t"
+ " sete %b1\n\t"
+ " movzbl %b1, %k1\n\t"
+ "# ending __down_write_trylock\n\t"
+ : "+m" (sem->count), "=&a" (result), "=&r" (tmp)
+ : "er" (RWSEM_ACTIVE_WRITE_BIAS)
+ : "memory", "cc");
+ return result;
}
/*
@@ -195,16 +152,16 @@ static inline int __down_write_trylock(struct rw_semaphore *sem)
*/
static inline void __up_read(struct rw_semaphore *sem)
{
- rwsem_count_t tmp = -RWSEM_ACTIVE_READ_BIAS;
+ long tmp;
asm volatile("# beginning __up_read\n\t"
LOCK_PREFIX " xadd %1,(%2)\n\t"
/* subtracts 1, returns the old value */
" jns 1f\n\t"
- " call call_rwsem_wake\n"
+ " call call_rwsem_wake\n" /* expects old value in %edx */
"1:\n"
"# ending __up_read\n"
: "+m" (sem->count), "=d" (tmp)
- : "a" (sem), "1" (tmp)
+ : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
: "memory", "cc");
}
@@ -213,13 +170,12 @@ static inline void __up_read(struct rw_semaphore *sem)
*/
static inline void __up_write(struct rw_semaphore *sem)
{
- rwsem_count_t tmp;
+ long tmp;
asm volatile("# beginning __up_write\n\t"
LOCK_PREFIX " xadd %1,(%2)\n\t"
- /* tries to transition
- 0xffff0001 -> 0x00000000 */
- " jz 1f\n"
- " call call_rwsem_wake\n"
+ /* subtracts 0xffff0001, returns the old value */
+ " jns 1f\n\t"
+ " call call_rwsem_wake\n" /* expects old value in %edx */
"1:\n\t"
"# ending __up_write\n"
: "+m" (sem->count), "=d" (tmp)
@@ -250,8 +206,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
/*
* implement atomic add functionality
*/
-static inline void rwsem_atomic_add(rwsem_count_t delta,
- struct rw_semaphore *sem)
+static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
{
asm volatile(LOCK_PREFIX _ASM_ADD "%1,%0"
: "+m" (sem->count)
@@ -261,21 +216,9 @@ static inline void rwsem_atomic_add(rwsem_count_t delta,
/*
* implement exchange and add functionality
*/
-static inline rwsem_count_t rwsem_atomic_update(rwsem_count_t delta,
- struct rw_semaphore *sem)
-{
- rwsem_count_t tmp = delta;
-
- asm volatile(LOCK_PREFIX "xadd %0,%1"
- : "+r" (tmp), "+m" (sem->count)
- : : "memory");
-
- return tmp + delta;
-}
-
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
+static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
{
- return (sem->count != 0);
+ return delta + xadd(&sem->count, delta);
}
#endif /* __KERNEL__ */
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-12-05 21:00:16 +0000