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authorThomas Gleixner <tglx@linutronix.de>2009-01-25 11:31:36 +0100
committerIngo Molnar <mingo@elte.hu>2009-01-30 22:35:34 +0100
commitb0a9b5111abf60ef07eade834f480e89004c7920 (patch)
treea74aa7bacf920eb567cd7caa8027a06c96dbb220
parent94df7de0289bc2df3d6e85cd2ece52bf42682f45 (diff)
hrtimer: prevent negative expiry value after clock_was_set()
Impact: prevent false positive WARN_ON() in clockevents_program_event() clock_was_set() changes the base->offset of CLOCK_REALTIME and enforces the reprogramming of the clockevent device to expire timers which are based on CLOCK_REALTIME. If the clock change is large enough then the subtraction of the timer expiry value and base->offset can become negative which triggers the warning in clockevents_program_event(). Check the subtraction result and set a negative value to 0. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--kernel/hrtimer.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 647a40e2fea1..f394d2a42ca3 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -501,6 +501,13 @@ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base)
continue;
timer = rb_entry(base->first, struct hrtimer, node);
expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+ /*
+ * clock_was_set() has changed base->offset so the
+ * result might be negative. Fix it up to prevent a
+ * false positive in clockevents_program_event()
+ */
+ if (expires.tv64 < 0)
+ expires.tv64 = 0;
if (expires.tv64 < cpu_base->expires_next.tv64)
cpu_base->expires_next = expires;
}