2.6.24-stable review patch. If anyone has any objections, please let us
know.
------------------
From: Thomas Gleixner <[EMAIL PROTECTED]>
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 <[EMAIL PROTECTED]>
Tested-by: Frans Pop <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
---
kernel/hrtimer.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -427,6 +427,8 @@ static int hrtimer_reprogram(struct hrti
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 hrti
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;
--
--
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