linux-kernel - Re: [BUG] ptraced process waiting on syscall may return kernel internal errnos

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Date:	Thu, 7 Jun 2007 09:07:44 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Roland McGrath <roland@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>,
	Oleg Nesterov <oleg@...sign.ru>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [BUG] ptraced process waiting on syscall may return kernel
 internal errnos

Linus Torvalds writes:

> So I think that the *right* place to clear TIF_SIGPENDING is actually in 
> "get_signal_to_deliver()", because that function is called _only_ by the 
> actual per-architecture "I'm going to deliver a signal now".

I agree that's the right place for real user processes, but I note
that there are drivers that have kernel threads that do basically
this:

	if (signal_pending(current))
		dequeue_signal(current, ...);

for example, drivers/block/nbd.c, and obviously they don't want to
still see signal_pending(current) after they have dequeued all the
pending signals.

Paul.
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