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signal: retarget_shared_pending: consider shared/unblocked signals only 

exit_signals() checks signal_pending() before retarget_shared_pending() but
this is suboptimal. We can avoid the while_each_thread() loop in case when
there are no shared signals visible to us.

Add the "shared_pending.signal & ~blocked" check. We don't use tsk->blocked
directly but pass ~blocked as an argument, this is needed for the next patch.

Note: we can optimize this more. while_each_thread(t) can check t->blocked
into account and stop after every pending signal has the new target, see the
next patch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Oleg Nesterov 2011-04-27 19:18:39 +02:00
parent 0edceb7bcd
commit f646e227b8
1 changed files with 10 additions and 2 deletions
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12
kernel/signal.c
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@ -2203,10 +2203,15 @@ relock:
* group-wide signal. Another thread should be notified now to take
* the signal since we will not.
*/
static void retarget_shared_pending(struct task_struct *tsk)
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
{
sigset_t retarget;
struct task_struct *t;
sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
if (sigisemptyset(&retarget))
return;
t = tsk;
while_each_thread(tsk, t) {
if (!signal_pending(t) && !(t->flags & PF_EXITING))
@ -2217,6 +2222,7 @@ static void retarget_shared_pending(struct task_struct *tsk)
void exit_signals(struct task_struct *tsk)
{
int group_stop = 0;
sigset_t unblocked;
if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
tsk->flags |= PF_EXITING;
@ -2232,7 +2238,9 @@ void exit_signals(struct task_struct *tsk)
if (!signal_pending(tsk))
goto out;
retarget_shared_pending(tsk);
unblocked = tsk->blocked;
signotset(&unblocked);
retarget_shared_pending(tsk, &unblocked);
if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) &&
task_participate_group_stop(tsk))