The write operation may be reordered with the setting of group_exit_task. If so, this fires in exit_notify().
Looks like, it's not good to add smp barriers for this case, especially in exit_notify(), so let's put the notify_count write under write lock. Signed-off-by: Kirill Tkhai <[email protected]> --- fs/exec.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index ad8798e..42782d5 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -920,10 +920,16 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) { struct task_struct *leader = tsk->group_leader; - sig->notify_count = -1; /* for exit_notify() */ for (;;) { threadgroup_change_begin(tsk); write_lock_irq(&tasklist_lock); + /* + * We could set it once outside the for() cycle, but + * this requires to use SMP barriers there and in + * exit_notify(), because the write operation may + * be reordered with the setting of group_exit_task. + */ + sig->notify_count = -1; /* for exit_notify() */ if (likely(leader->exit_state)) break; __set_current_state(TASK_KILLABLE); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
