Commit d563c54e authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds

[PATCH] More timer race fixes

Patch from Julie DeWandel.

This patch has solved the crashes observed during TPC-C runs on the
16-way box.  (I'm confident it will fix the other reported cases as
well.)

The race is the setting of timer->base to NULL, by del_timer() or
__run_timers().  If new_base == old_base in __mod_timer() then we do not
re-check timer->base after getting the lock.  (the only case where we do
not have to re-check the base is in the !old_base case, but the else
branch also includes the old_base==new_base case.)

The __run_timers() case made the lock_timer() patch not work fully - we
cannot use lock_timer() in __run_timers() due to lock ordering.
parent 00ed8a2c
......@@ -179,8 +179,13 @@ int __mod_timer(struct timer_list *timer, unsigned long expires)
spin_unlock(&old_base->lock);
goto repeat;
}
} else
} else {
spin_lock(&new_base->lock);
if (timer->base != old_base) {
spin_unlock(&new_base->lock);
goto repeat;
}
}
/*
* Delete the previous timeout (if there was any), and install
......
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