diff options
author | Oleg Nesterov <oleg@redhat.com> | 2010-05-26 21:43:10 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 16:12:45 (GMT) |
commit | 9c3391684415c9dca239130d9e433a60a4edf04b (patch) | |
tree | a8019b964c625cfeeda0e9d85bafa48991546212 | |
parent | 269b005a28e124a341df4adef2c3661cf7371fcc (diff) | |
download | linux-fsl-qoriq-9c3391684415c9dca239130d9e433a60a4edf04b.tar.xz |
exit: exit_notify() can trust signal->notify_count < 0
signal_struct->count in its current form must die.
- it has no reasons to be atomic_t
- it looks like a reference counter, but it is not
- otoh, we really need to make task->signal refcountable, just look at
the extremely ugly task_rq_unlock_wait() called from __exit_signals().
- we should change the lifetime rules for task->signal, it should be
pinned to task_struct. We have a lot of code which can be simplified
after that.
- it is not needed! while the code is correct, any usage of this
counter is artificial, except fs/proc uses it correctly to show the
number of threads.
This series removes the usage of sig->count from exit pathes.
This patch:
Now that Veaceslav changed copy_signal() to use zalloc(), exit_notify()
can just check notify_count < 0 to ensure the execing sub-threads needs
the notification from us. No need to do other checks, notify_count != 0
must always mean ->group_exit_task != NULL is waiting for us.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | kernel/exit.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 019a284..59a104c 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -856,12 +856,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead) tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE; - /* mt-exec, de_thread() is waiting for us */ - if (thread_group_leader(tsk) && - tsk->signal->group_exit_task && - tsk->signal->notify_count < 0) + /* mt-exec, de_thread() is waiting for group leader */ + if (unlikely(tsk->signal->notify_count < 0)) wake_up_process(tsk->signal->group_exit_task); - write_unlock_irq(&tasklist_lock); tracehook_report_death(tsk, signal, cookie, group_dead); |