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, 7 insertions, 5 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 870b75e348a..d58e74b9836 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1616,11 +1616,13 @@ static inline int lock_need_resched(spinlock_t *lock)
 	return 0;
 }
 
-/* Reevaluate whether the task has signals pending delivery.
-   This is required every time the blocked sigset_t changes.
-   callers must hold sighand->siglock.  */
-
-extern FASTCALL(void recalc_sigpending_tsk(struct task_struct *t));
+/*
+ * Reevaluate whether the task has signals pending delivery.
+ * Wake the task if so.
+ * This is required every time the blocked sigset_t changes.
+ * callers must hold sighand->siglock.
+ */
+extern void recalc_sigpending_and_wake(struct task_struct *t);
 extern void recalc_sigpending(void);
 
 extern void signal_wake_up(struct task_struct *t, int resume_stopped);