[PATCH 2/6] signal: retarget_shared_pending: considershared/unblocked signals only

From: Oleg Nesterov
Date: Mon Apr 11 2011 - 13:21:55 EST

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 has_pending_signals(shared_pending, blocked) check. We don not use
tsk->blocked directly but pass this sigset_t 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.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

kernel/signal.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- sigprocmask/kernel/signal.c~2_optimize_retarget 2011-04-10 19:33:45.000000000 +0200
+++ sigprocmask/kernel/signal.c 2011-04-10 21:54:24.000000000 +0200
@@ -2022,10 +2022,13 @@ 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 *blocked)
struct task_struct *t;

+ if (!has_pending_signals(&tsk->signal->shared_pending.signal, blocked))
+ return;
t = tsk;
while_each_thread(tsk, t) {
if (!signal_pending(t) && !(t->flags & PF_EXITING))
@@ -2051,7 +2054,7 @@ void exit_signals(struct task_struct *ts
if (!signal_pending(tsk))
goto out;

- retarget_shared_pending(tsk);
+ retarget_shared_pending(tsk, &tsk->blocked);

if (unlikely(tsk->signal->group_stop_count) &&
!--tsk->signal->group_stop_count) {

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