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exit: avoid sig->count in de_thread/__exit_signal synchronization

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de_thread() and __exit_signal() use signal_struct->count/notify_count for
synchronization.  We can simplify the code and use ->notify_count only.
Instead of comparing these two counters, we can change de_thread() to set
->notify_count = nr_of_sub_threads, then change __exit_signal() to
dec-and-test this counter and notify group_exit_task.

Note that __exit_signal() checks "notify_count > 0" just for symmetry with
exit_notify(), we could just check it is != 0.

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>
This commit is contained in:
Oleg Nesterov
2010-05-26 14:43:11 -07:00
committed by Linus Torvalds
parent 09faef11df
commit d344193a05
2 changed files with 7 additions and 8 deletions
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2
kernel/exit.c
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@ -97,7 +97,7 @@ static void __exit_signal(struct task_struct *tsk)
* If there is any task waiting for the group exit
* then notify it:
*/
if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
if (sig->notify_count > 0 && !--sig->notify_count)
wake_up_process(sig->group_exit_task);
if (tsk == sig->curr_target)