From: Thomas Gleixner Date: Wed, 13 Feb 2008 23:58:36 +0000 (+0100) Subject: hrtimer: catch expired CLOCK_REALTIME timers early X-Git-Tag: v2.6.25-rc2~6^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=63070a79ba482c274bad10ac8c4b587a3e011f2c;p=linux-2.6 hrtimer: catch expired CLOCK_REALTIME timers early 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 Tested-by: Frans Pop --- diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index c2893af947..98bee013f7 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -442,6 +442,8 @@ 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 @@ -452,6 +454,15 @@ 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;