Re: [PATCH] simplify update_times (avoid jiffies/jiffies_64 aliasing problem)

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

akpm> I'm not sure how to resolve this, really.  Worried.  Have you
akpm> socialised those changes with architecture maintainers?  If so,
akpm> what was the feedback?

For a short term fix, barrier() might be a safe option.


Add an optimization barrier to prevent prefetching jiffies before
incrementing jiffies_64.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

diff --git a/kernel/timer.c b/kernel/timer.c
index fc6646f..fdd12a5 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -925,6 +925,7 @@ static inline void update_times(void)
 void do_timer(struct pt_regs *regs)
 {
 	jiffies_64++;
+	barrier();
 	update_times();
 	softlockup_tick(regs);
 }
-
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