diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2010-05-26 14:43:11 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 09:12:46 -0700 |
| commit | d344193a05da89c97e965da2c5cbf687d7385eae (patch) | |
| tree | 6267b68c31c4547f1749acd35d2a5bfaff919839 | |
| parent | 09faef11df8c559a23e2405d123cb2683733a79a (diff) | |
| download | blackbird-op-linux-d344193a05da89c97e965da2c5cbf687d7385eae.tar.gz blackbird-op-linux-d344193a05da89c97e965da2c5cbf687d7385eae.zip | |
exit: avoid sig->count in de_thread/__exit_signal synchronization
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>
| -rw-r--r-- | fs/exec.c | 11 | ||||
| -rw-r--r-- | kernel/exit.c | 2 |
2 files changed, 6 insertions, 7 deletions
diff --git a/fs/exec.c b/fs/exec.c index 0c72d23ed0e2..e19de6a80339 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -768,7 +768,6 @@ static int de_thread(struct task_struct *tsk) struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; - int count; if (thread_group_empty(tsk)) goto no_thread_group; @@ -785,13 +784,13 @@ static int de_thread(struct task_struct *tsk) spin_unlock_irq(lock); return -EAGAIN; } + sig->group_exit_task = tsk; - zap_other_threads(tsk); + sig->notify_count = zap_other_threads(tsk); + if (!thread_group_leader(tsk)) + sig->notify_count--; - /* Account for the thread group leader hanging around: */ - count = thread_group_leader(tsk) ? 1 : 2; - sig->notify_count = count; - while (atomic_read(&sig->count) > count) { + while (sig->notify_count) { __set_current_state(TASK_UNINTERRUPTIBLE); spin_unlock_irq(lock); schedule(); diff --git a/kernel/exit.c b/kernel/exit.c index 59a104c673f7..9220967f4256 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -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) |
