Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/lin…

…ux/kernel/git/tip/linux-2.6-tip * 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: move rdtsc_barrier() into the TSC vread method
git-mirror · Jun 10, 2009 · 595dc54 · 595dc54
2 parents 9b29e82 + 7d96fd4
commit 595dc54
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Showing 2 changed files with 10 additions and 9 deletions.
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
@@ -710,7 +710,16 @@ static cycle_t read_tsc(struct clocksource *cs)
 #ifdef CONFIG_X86_64
 static cycle_t __vsyscall_fn vread_tsc(void)
 {
-	cycle_t ret = (cycle_t)vget_cycles();
+	cycle_t ret;
+
+	/*
+	 * Surround the RDTSC by barriers, to make sure it's not
+	 * speculated to outside the seqlock critical section and
+	 * does not cause time warps:
+	 */
+	rdtsc_barrier();
+	ret = (cycle_t)vget_cycles();
+	rdtsc_barrier();
 
 	return ret >= __vsyscall_gtod_data.clock.cycle_last ?
 		ret : __vsyscall_gtod_data.clock.cycle_last;

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
@@ -132,15 +132,7 @@ static __always_inline void do_vgettimeofday(struct timeval * tv)
 			return;
 		}
 
-		/*
-		 * Surround the RDTSC by barriers, to make sure it's not
-		 * speculated to outside the seqlock critical section and
-		 * does not cause time warps:
-		 */
-		rdtsc_barrier();
 		now = vread();
-		rdtsc_barrier();
-
 		base = __vsyscall_gtod_data.clock.cycle_last;
 		mask = __vsyscall_gtod_data.clock.mask;
 		mult = __vsyscall_gtod_data.clock.mult;