linux-kernel - Re: avr32: handle

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Message-ID: <1313488648.3436.126.camel@mfleming-mobl1.ger.corp.intel.com>
Date:	Tue, 16 Aug 2011 10:57:28 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Håvard Skinnemoen <hskinnemoen@...il.com>
Cc:	Hans-Christian Egtvedt <egtvedt@...fundet.no>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: avr32: handle_signal() bug?

On Mon, 2011-08-15 at 22:55 -0700, Håvard Skinnemoen wrote:
> Hi,
> 
> Sorry for taking so long to test this.

No worries!

> On Mon, Aug 8, 2011 at 3:25 AM, Matt Fleming <matt@...sole-pimps.org> wrote:
> > On Sun, 2011-08-07 at 10:20 -0700, Håvard Skinnemoen wrote:
> >> Looks good to me. I'm not sure how to test it though...I can try to
> >> build a kernel, run it on my board and see if it explodes, but I
> >> suspect this bug is a lot more subtle than that.
> >
> > I suspect the best test would be one that makes use of SA_NODEFER.
> > Something like this,
> 
> Thanks for the test. Unfortunately, the result is the same regardless
> of whether I apply the patches or not. In both cases:
> 
> /root # ./nodefer
> SIGUSR2: not blocked
> SIGTERM: not blocked

Hmm.. that's interesting. I had a quick look through the rest of the
code in the signal path and couldn't find anything obviously wrong. The
only thing that looked suspicious is that you don't clear
TIF_RESTORE_SIGMASK if you successsfully deliver a signal. Maybe try
adding a clear_thread_flag(TIF_RESTORE_SIGMASK); to the success path in
handle_signal() and see if you get better results? See the x86
implementation for more details.

> On my desktop, it behaves as expected:
> 
> $ ./nodefer-pc
> SIGUSR2: blocked
> SIGTERM: blocked
> 
> Your patch doesn't appear to do any harm though, and it looks correct
> to me. Perhaps there's another bug lurking somewhere as well. Some
> preliminary debugging makes me suspicious about libc, but I can't tell
> for sure yet.

Which libc is this by the way?

-- 
Matt Fleming, Intel Open Source Technology Center

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