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authorIngo Molnar <mingo@elte.hu>2009-05-17 11:08:41 +0200
committerIngo Molnar <mingo@elte.hu>2009-05-20 00:22:24 +0200
commit33b2fb303fe7f6b08bbb32f708e67b96eaa94a7a (patch)
tree32ab4cb3cca6c61a2d6cf351bb8f732045464e28 /kernel/exit.c
parentperf_counter, x86: speed up the scheduling fast-path (diff)
downloadlinux-33b2fb303fe7f6b08bbb32f708e67b96eaa94a7a.tar.xz
linux-33b2fb303fe7f6b08bbb32f708e67b96eaa94a7a.zip
perf_counter: fix counter freeing logic
Fix counter lifetime bugs which explain the crashes reported by Marcelo Tosatti and Arnaldo Carvalho de Melo. The new rule is: flushing + freeing is only done for a task's own counters, never for other tasks. [ Impact: fix crashes/lockups with inherited counters ] Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Reported-by: Marcelo Tosatti <mtosatti@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c19
1 files changed, 7 insertions, 12 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 73affd35e76d..f9dfedd94af0 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -178,12 +178,6 @@ repeat:
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);
@@ -985,6 +979,13 @@ NORET_TYPE void do_exit(long code)
module_put(tsk->binfmt->module);
proc_exit_connector(tsk);
+
+ /*
+ * Flush inherited counters to the parent - before the parent
+ * gets woken up by child-exit notifications.
+ */
+ perf_counter_exit_task(tsk);
+
exit_notify(tsk, group_dead);
#ifdef CONFIG_NUMA
mpol_put(tsk->mempolicy);
@@ -1257,12 +1258,6 @@ static int wait_task_zombie(struct task_struct *p, int options,
*/
read_unlock(&tasklist_lock);
- /*
- * Flush inherited counters to the parent - before the parent
- * gets woken up by child-exit notifications.
- */
- perf_counter_exit_task(p);
-
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
status = (p->signal->flags & SIGNAL_GROUP_EXIT)
? p->signal->group_exit_code : p->exit_code;