From b1f82ca6fed5f40af990a9622eb798927f431756 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Fri, 8 Feb 2008 04:19:18 -0800
Subject: [PATCH] --- yaml --- r: 84671 b: refs/heads/master c:
 d36174bc2bce0372693a9cfbdef8b2689c9982cb h: refs/heads/master i:   84669:
 435f932642ee59e31d2f689b51f0b9d56dcf72fb   84667:
 69bdfc8898e8968395adceae515036d1f18af718   84663:
 b16a3917dc05e7679cf50cad92ff3fa6c635c392   84655:
 ba552461e389361a0efeaa963bd84a20719234bd   84639:
 7d3a65a050f27ea90180b4ac587aeec6f117e9ae   84607:
 824f890c7cb8b180c0fc7269d4dd9a86200ea797 v: v3

---
 [refs]                |  2 +-
 trunk/kernel/signal.c | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 88cf3f68f31e..ee0d1b7b05c8 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f374ada53bd1ca7c16d7607369fccc6769704956
+refs/heads/master: d36174bc2bce0372693a9cfbdef8b2689c9982cb
diff --git a/trunk/kernel/signal.c b/trunk/kernel/signal.c
index 3d3adb94561d..b0b43a4ad8dd 100644
--- a/trunk/kernel/signal.c
+++ b/trunk/kernel/signal.c
@@ -1050,17 +1050,26 @@ int kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
 
 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
 {
-	int error;
+	int error = -ESRCH;
 	struct task_struct *p;
 
 	rcu_read_lock();
 	if (unlikely(sig_needs_tasklist(sig)))
 		read_lock(&tasklist_lock);
 
+retry:
 	p = pid_task(pid, PIDTYPE_PID);
-	error = -ESRCH;
-	if (p)
+	if (p) {
 		error = group_send_sig_info(sig, info, p);
+		if (unlikely(error == -ESRCH))
+			/*
+			 * The task was unhashed in between, try again.
+			 * If it is dead, pid_task() will return NULL,
+			 * if we race with de_thread() it will find the
+			 * new leader.
+			 */
+			goto retry;
+	}
 
 	if (unlikely(sig_needs_tasklist(sig)))
 		read_unlock(&tasklist_lock);