linux-kernel - Re: signalfd API issues (was Re: [PATCH/RFC] signal races/bugs, losing TIF

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Date:	Thu, 7 Jun 2007 08:43:42 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Jeff Dike <jdike@...toit.com>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Nicholas Miell <nmiell@...cast.net>,
	Davide Libenzi <davidel@...ilserver.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: signalfd API issues (was Re: [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes)

Jeff Dike writes:

> On Wed, Jun 06, 2007 at 12:50:04PM +1000, Benjamin Herrenschmidt wrote:
> > Yeah, synchronous signals should probably never be delivered to another
> > process, even via signalfd. There's no point delivering a SEGV to
> > somebody else :-)
> 
> Sure there is.  UML does exactly that - intercepting child signals
> (including SEGV) with wait.

What Ben was talking about was stealing a synchronous SEGV from a task
without stopping it, and as Ben says that makes no sense.
Intercepting a signal and stopping the task is reasonable, and that is
what ptrace does, and I assume also UML.

Paul.
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