From f8738c5c5298d55ccfc26383f9f45af082a9be57 Mon Sep 17 00:00:00 2001
From: Davide Libenzi <davidel@xmailserver.org>
Date: Wed, 27 Jun 2007 14:09:59 -0700
Subject: [PATCH] avoid spurious POLLIN returns in signalfd

The new code in kernel/signal.c does not allow fetching private signals
from another task.  This patch avoid spurious POLLIN returns from a
signalfd poll(2) operation.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
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>
---
 fs/signalfd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index f1da89203a9a..3b07f26d984d 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -133,7 +133,8 @@ static unsigned int signalfd_poll(struct file *file, poll_table *wait)
 	 * the peer disconnects.
 	 */
 	if (signalfd_lock(ctx, &lk)) {
-		if (next_signal(&lk.tsk->pending, &ctx->sigmask) > 0 ||
+		if ((lk.tsk == current &&
+		     next_signal(&lk.tsk->pending, &ctx->sigmask) > 0) ||
 		    next_signal(&lk.tsk->signal->shared_pending,
 				&ctx->sigmask) > 0)
 			events |= POLLIN;