timer: Try to survive timer callback preempt_count leak

[safe/jmp/linux-2.6] / kernel / timer.c

diff --git a/kernel/timer.c b/kernel/timer.c
index 4522969..7e12e7b 100644 (file)
--- 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;
        }
 }