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-rw-r--r--arch/x86/include/asm/atomic_32.h9
-rw-r--r--arch/x86/lib/atomic64_32.c21
2 files changed, 15 insertions, 15 deletions
diff --git a/arch/x86/include/asm/atomic_32.h b/arch/x86/include/asm/atomic_32.h
index aa045deb2e75..d7c8849b8c67 100644
--- a/arch/x86/include/asm/atomic_32.h
+++ b/arch/x86/include/asm/atomic_32.h
@@ -268,15 +268,6 @@ typedef struct {
268 268
269#define ATOMIC64_INIT(val) { (val) } 269#define ATOMIC64_INIT(val) { (val) }
270 270
271/**
272 * atomic64_read - read atomic64 variable
273 * @ptr: pointer of type atomic64_t
274 *
275 * Atomically reads the value of @v.
276 * Doesn't imply a read memory barrier.
277 */
278#define __atomic64_read(ptr) ((ptr)->counter)
279
280extern u64 atomic64_cmpxchg(atomic64_t *ptr, u64 old_val, u64 new_val); 271extern u64 atomic64_cmpxchg(atomic64_t *ptr, u64 old_val, u64 new_val);
281 272
282/** 273/**
diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c
index 6722a092e407..a804f96e90e2 100644
--- a/arch/x86/lib/atomic64_32.c
+++ b/arch/x86/lib/atomic64_32.c
@@ -33,14 +33,23 @@ EXPORT_SYMBOL(atomic64_cmpxchg);
33 * Atomically xchgs the value of @ptr to @new_val and returns 33 * Atomically xchgs the value of @ptr to @new_val and returns
34 * the old value. 34 * the old value.
35 */ 35 */
36
37u64 atomic64_xchg(atomic64_t *ptr, u64 new_val) 36u64 atomic64_xchg(atomic64_t *ptr, u64 new_val)
38{ 37{
39 u64 old_val; 38 /*
39 * Try first with a (possibly incorrect) assumption about
40 * what we have there. We'll do two loops most likely,
41 * but we'll get an ownership MESI transaction straight away
42 * instead of a read transaction followed by a
43 * flush-for-ownership transaction:
44 */
45 u64 old_val, real_val = 0;
40 46
41 do { 47 do {
42 old_val = __atomic64_read(ptr); 48 old_val = real_val;
43 } while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val); 49
50 real_val = atomic64_cmpxchg(ptr, old_val, new_val);
51
52 } while (real_val != old_val);
44 53
45 return old_val; 54 return old_val;
46} 55}
@@ -91,13 +100,13 @@ EXPORT_SYMBOL(atomic64_read);
91noinline u64 atomic64_add_return(u64 delta, atomic64_t *ptr) 100noinline u64 atomic64_add_return(u64 delta, atomic64_t *ptr)
92{ 101{
93 /* 102 /*
94 * Try first with a (probably incorrect) assumption about 103 * Try first with a (possibly incorrect) assumption about
95 * what we have there. We'll do two loops most likely, 104 * what we have there. We'll do two loops most likely,
96 * but we'll get an ownership MESI transaction straight away 105 * but we'll get an ownership MESI transaction straight away
97 * instead of a read transaction followed by a 106 * instead of a read transaction followed by a
98 * flush-for-ownership transaction: 107 * flush-for-ownership transaction:
99 */ 108 */
100 u64 old_val, new_val, real_val = 1ULL << 32; 109 u64 old_val, new_val, real_val = 0;
101 110
102 do { 111 do {
103 old_val = real_val; 112 old_val = real_val;