Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4071c718555d955a35e9651f77086096ad87d498
Commit: 4071c718555d955a35e9651f77086096ad87d498
Parent: df1bdc0667eb3132fe60b3562347ca9133694ee0
Author: Nick Piggin <[EMAIL PROTECTED]>
AuthorDate: Sat Oct 13 03:06:55 2007 +0200
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Oct 12 18:41:21 2007 -0700
x86: fix IO write barrier
wmb() on x86 must always include a barrier, because stores can go out of
order in many cases when dealing with devices (eg. WC memory).
Signed-off-by: Nick Piggin <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
include/asm-x86/system_32.h | 15 ++++++---------
include/asm-x86/system_64.h | 6 +-----
2 files changed, 7 insertions(+), 14 deletions(-)
diff --git a/include/asm-x86/system_32.h b/include/asm-x86/system_32.h
index d69ba93..8b15bd3 100644
--- a/include/asm-x86/system_32.h
+++ b/include/asm-x86/system_32.h
@@ -216,6 +216,7 @@ static inline unsigned long get_limit(unsigned long segment)
#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
+#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
/**
* read_barrier_depends - Flush all pending reads that subsequents reads
@@ -271,18 +272,14 @@ static inline unsigned long get_limit(unsigned long
segment)
#define read_barrier_depends() do { } while(0)
-#ifdef CONFIG_X86_OOSTORE
-/* Actually there are no OOO store capable CPUs for now that do SSE,
- but make it already an possibility. */
-#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
-#else
-#define wmb() __asm__ __volatile__ ("": : :"memory")
-#endif
-
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
-#define smp_wmb() wmb()
+#ifdef CONFIG_X86_OOSTORE
+# define smp_wmb() wmb()
+#else
+# define smp_wmb() barrier()
+#endif
#define smp_read_barrier_depends() read_barrier_depends()
#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
#else
diff --git a/include/asm-x86/system_64.h b/include/asm-x86/system_64.h
index 02175aa..eff730b 100644
--- a/include/asm-x86/system_64.h
+++ b/include/asm-x86/system_64.h
@@ -159,12 +159,8 @@ static inline void write_cr8(unsigned long val)
*/
#define mb() asm volatile("mfence":::"memory")
#define rmb() asm volatile("lfence":::"memory")
-
-#ifdef CONFIG_UNORDERED_IO
#define wmb() asm volatile("sfence" ::: "memory")
-#else
-#define wmb() asm volatile("" ::: "memory")
-#endif
+
#define read_barrier_depends() do {} while(0)
#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
-
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