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@@ -118,7 +118,7 @@ static inline void __down_read(struct rw_semaphore *sem)
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{
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asm volatile("# beginning down_read\n\t"
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LOCK_PREFIX _ASM_INC "(%1)\n\t"
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- /* adds 0x00000001, returns the old value */
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+ /* adds 0x00000001 */
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" jns 1f\n"
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" call call_rwsem_down_read_failed\n"
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"1:\n\t"
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@@ -156,11 +156,9 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
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static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
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{
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rwsem_count_t tmp;
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-
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- tmp = RWSEM_ACTIVE_WRITE_BIAS;
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asm volatile("# beginning down_write\n\t"
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LOCK_PREFIX " xadd %1,(%2)\n\t"
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- /* subtract 0x0000ffff, returns the old value */
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+ /* adds 0xffff0001, returns the old value */
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" test %1,%1\n\t"
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/* was the count 0 before? */
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" jz 1f\n"
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@@ -168,7 +166,7 @@ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
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"1:\n"
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"# ending down_write"
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: "+m" (sem->count), "=d" (tmp)
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- : "a" (sem), "1" (tmp)
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+ : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
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: "memory", "cc");
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}
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@@ -195,16 +193,16 @@ static inline int __down_write_trylock(struct rw_semaphore *sem)
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*/
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static inline void __up_read(struct rw_semaphore *sem)
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{
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- rwsem_count_t tmp = -RWSEM_ACTIVE_READ_BIAS;
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+ rwsem_count_t tmp;
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asm volatile("# beginning __up_read\n\t"
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LOCK_PREFIX " xadd %1,(%2)\n\t"
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/* subtracts 1, returns the old value */
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" jns 1f\n\t"
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- " call call_rwsem_wake\n"
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+ " call call_rwsem_wake\n" /* expects old value in %edx */
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"1:\n"
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"# ending __up_read\n"
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: "+m" (sem->count), "=d" (tmp)
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- : "a" (sem), "1" (tmp)
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+ : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
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: "memory", "cc");
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}
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@@ -216,10 +214,9 @@ static inline void __up_write(struct rw_semaphore *sem)
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rwsem_count_t tmp;
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asm volatile("# beginning __up_write\n\t"
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LOCK_PREFIX " xadd %1,(%2)\n\t"
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- /* tries to transition
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- 0xffff0001 -> 0x00000000 */
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- " jz 1f\n"
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- " call call_rwsem_wake\n"
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+ /* subtracts 0xffff0001, returns the old value */
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+ " jns 1f\n\t"
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+ " call call_rwsem_wake\n" /* expects old value in %edx */
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"1:\n\t"
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"# ending __up_write\n"
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: "+m" (sem->count), "=d" (tmp)
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