perf_counter: fix threaded task exit
Flushing counters in __exit_signal() with irqs disabled is not
a good idea as perf_counter_exit_task() acquires mutexes. So
flush it before acquiring the tasklist lock.
(Note, we still need a fix for when the PID has been unhashed.)
[ Impact: fix crash with inherited counters ]
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/exit.c b/kernel/exit.c
index 16d74f1..73affd3 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -128,12 +128,6 @@
sig = NULL; /* Marker for below. */
}
- /*
- * Flush inherited counters to the parent - before the parent
- * gets woken up by child-exit notifications.
- */
- perf_counter_exit_task(tsk);
-
__unhash_process(tsk);
/*
@@ -183,6 +177,13 @@
atomic_dec(&__task_cred(p)->user->processes);
proc_flush_task(p);
+
+ /*
+ * Flush inherited counters to the parent - before the parent
+ * gets woken up by child-exit notifications.
+ */
+ perf_counter_exit_task(p);
+
write_lock_irq(&tasklist_lock);
tracehook_finish_release_task(p);
__exit_signal(p);
