1 files changed, 21 insertions, 7 deletions

diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index 2dbe4a721ce5..cad82c9c2fde 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -105,8 +105,8 @@ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
         asm volatile("# beginning down_write\n\t"
                      LOCK_PREFIX "  xadd      %1,(%2)\n\t"
                      /* adds 0xffff0001, returns the old value */
-                     "  test      %1,%1\n\t"
-                     /* was the count 0 before? */
+                     "  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"
@@ -126,11 +126,25 @@ static inline void __down_write(struct rw_semaphore *sem)
  */
 static inline int __down_write_trylock(struct rw_semaphore *sem)
 {
-        long 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;
 }
 
 /*