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author | Thomas Gleixner <tglx@linutronix.de> | 2010-03-12 20:13:23 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2010-03-12 22:40:44 +0100 |
commit | 802702e0c2618465b813242d4dfee6a233ba0beb (patch) | |
tree | e21c74065e82a77c45c4f815c626fbafc7fff469 /kernel | |
parent | 576da126a6c7364d70dfd58d0bbe43d05cf5859f (diff) | |
download | kernel_samsung_tuna-802702e0c2618465b813242d4dfee6a233ba0beb.zip kernel_samsung_tuna-802702e0c2618465b813242d4dfee6a233ba0beb.tar.gz kernel_samsung_tuna-802702e0c2618465b813242d4dfee6a233ba0beb.tar.bz2 |
timer: Try to survive timer callback preempt_count leak
If a timer callback leaks preempt_count we currently assert a
BUG(). That makes it unnecessarily hard to retrieve information about
the problem especially on laptops and headless stations.
There is a decent chance to survive the preempt_count leak by
restoring the preempt_count to the value before the callback. That
allows in many cases to get valuable information about the root cause
of the problem.
We carried that fixup in preempt-rt for years and were able to decode
such wreckage quite a few times.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/timer.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 4522969..7e12e7b 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -982,9 +982,15 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long), lock_map_release(&lockdep_map); if (preempt_count != preempt_count()) { - printk(KERN_ERR "timer: %pF preempt leak: %08x -> %08x\n", - fn, preempt_count, preempt_count()); - BUG(); + WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n", + fn, preempt_count, preempt_count()); + /* + * Restore the preempt count. That gives us a decent + * chance to survive and extract information. If the + * callback kept a lock held, bad luck, but not worse + * than the BUG() we had. + */ + preempt_count() = preempt_count; } } |