recalc_sigpending_tsk fixes

Steve Hawkes discovered a problem where recalc_sigpending_tsk was called in
do_sigaction but no signal_wake_up call was made, preventing later signals
from waking up blocked threads with TIF_SIGPENDING already set.

In fact, the few other calls to recalc_sigpending_tsk outside the signals
code are also subject to this problem in other race conditions.

This change makes recalc_sigpending_tsk private to the signals code.  It
changes the outside calls, as well as do_sigaction, to use the new
recalc_sigpending_and_wake instead.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: <Steve.Hawkes@motorola.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index c6d14b8008dd..5b888c24e43e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -762,11 +762,8 @@ static void exit_notify(struct task_struct *tsk)
                 read_lock(&tasklist_lock);
                 spin_lock_irq(&tsk->sighand->siglock);
                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
-                        if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
-                                recalc_sigpending_tsk(t);
-                                if (signal_pending(t))
-                                        signal_wake_up(t, 0);
-                        }
+                        if (!signal_pending(t) && !(t->flags & PF_EXITING))
+                                recalc_sigpending_and_wake(t);
                 spin_unlock_irq(&tsk->sighand->siglock);
                 read_unlock(&tasklist_lock);
         }