[PATCH] time: add barrier after updating jiffies_64

Add a compiler barrier so that we don't read jiffies before updating
jiffies_64.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/timer.c b/kernel/timer.c
index 8256f3f..bf7c419 100644 (file)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -941,6 +941,8 @@ static inline void update_times(void)
 void do_timer(struct pt_regs *regs)
 {
        jiffies_64++;
+       /* prevent loading jiffies before storing new jiffies_64 value. */
+       barrier();
        update_times();
        softlockup_tick(regs);
 }