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authorThomas Gleixner <tglx@linutronix.de>2008-02-20 01:04:56 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2008-02-25 16:18:57 -0800
commit4813a83f2665f7276f1e4eee9cffe45116cf3824 (patch)
treec90ab757087895606343902813d0c563a9df88bf
parent85d1617924607c1311962546bb55367b9edb4ca6 (diff)
hrtimer: catch expired CLOCK_REALTIME timers early
commit 63070a79ba482c274bad10ac8c4b587a3e011f2c A CLOCK_REALTIME timer, which has an absolute expiry time less than the clock realtime offset calls with a negative delta into the clock events code and triggers the WARN_ON() there. This is a false positive and needs to be prevented. Check the result of timer->expires - timer->base->offset right away and return -ETIME right away. Thanks to Frans Pop, who reported the problem and tested the fixes. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Frans Pop <elendil@planet.nl> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--kernel/hrtimer.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 2ed800218e5e..2429893a6bbe 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -427,6 +427,8 @@ static int hrtimer_reprogram(struct hrtimer *timer,
ktime_t expires = ktime_sub(timer->expires, base->offset);
int res;
+ WARN_ON_ONCE(timer->expires.tv64 < 0);
+
/*
* When the callback is running, we do not reprogram the clock event
* device. The timer callback is either running on a different CPU or
@@ -437,6 +439,15 @@ static int hrtimer_reprogram(struct hrtimer *timer,
if (hrtimer_callback_running(timer))
return 0;
+ /*
+ * CLOCK_REALTIME timer might be requested with an absolute
+ * expiry time which is less than base->offset. Nothing wrong
+ * about that, just avoid to call into the tick code, which
+ * has now objections against negative expiry values.
+ */
+ if (expires.tv64 < 0)
+ return -ETIME;
+
if (expires.tv64 >= expires_next->tv64)
return 0;