[PATCH 2/7] [PATCH] NPTL signal delivery deadlock fix

[Chris Wright <chrisw@osdl.org>]

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-stable review patch.  If anyone has any  objections, please let us know.
------------------

This bug is quite subtle and only happens in a very interesting
situation where a real-time threaded process is in the middle of a
coredump when someone whacks it with a SIGKILL. However, this deadlock
leaves the system pretty hosed and you have to reboot to recover.

Not good for real-time priority-preemption applications like our
telephony application, with 90+ real-time (SCHED_FIFO and SCHED_RR)
processes, many of them multi-threaded, interacting with each other for
high volume call processing.

Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Chris Wright <chrisw@osdl.org>
---
 kernel/signal.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.12.y/kernel/signal.c
===================================================================
--- linux-2.6.12.y.orig/kernel/signal.c
+++ linux-2.6.12.y/kernel/signal.c
@@ -686,7 +686,7 @@ static void handle_stop_signal(int sig, 
 {
 	struct task_struct *t;
 
-	if (p->flags & SIGNAL_GROUP_EXIT)
+	if (p->signal->flags & SIGNAL_GROUP_EXIT)
 		/*
 		 * The process is in the middle of dying already.
 		 */

--