Re: [PATCH 2.6.12.5] NPTL signal delivery deadlock fix

[Chris Wright <chrisw@osdl.org>]

* Bhavesh P. Davda (bhavesh@avaya.com) wrote:
> 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.

Nice catch, also looks like something for -stable series.  Roland, any
issue with this patch?

thanks,
-chris

> diff -Naur linux-2.6.12.5/kernel/signal.c linux-2.6.12.5-sigfix/kernel/signal.c
> --- linux-2.6.12.5/kernel/signal.c	2005-08-14 18:20:18.000000000 -0600
> +++ linux-2.6.12.5-sigfix/kernel/signal.c	2005-08-17 11:36:20.547600092 -0600
> @@ -686,7 +686,7 @@
>  {
>  	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.
>  		 */