linux-kernel - Re: avr32: handle

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Date:	Tue, 16 Aug 2011 22:14:16 -0700
From:	Håvard Skinnemoen <hskinnemoen@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Matt Fleming <matt@...sole-pimps.org>,
	Hans-Christian Egtvedt <egtvedt@...fundet.no>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: avr32: handle_signal() bug?

On Tue, Aug 16, 2011 at 8:39 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> On 08/16, Matt Fleming wrote:
>> Maybe try
>> adding a clear_thread_flag(TIF_RESTORE_SIGMASK); to the success path in
>> handle_signal() and see if you get better results?
>
> I will be surprised if this helps with this particular test-case,
> but I agree this should be fixed anyway.

Yeah, we should get that fixed.

>> > 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?
>
> may be you can run the test-case under strace? On my machine
> strace -f -e rt_sigprocmask ./test shows
>
>        [pid 25610] --- SIGUSR1 (User defined signal 1) @ 0 (0) ---
>        [pid 25610] rt_sigprocmask(SIG_BLOCK, NULL, [USR2 TERM], 8) = 0

Hmm, doing that makes my board reboot. I guess we're having trouble
with ptrace() as well...somehow the pid parameter to kill() gets
turned into 1 when running under strace, and it just so happens that
busybox's init interprets SIGUSR1 as "halt".

kill(1, SIGUSR1)                        = 0

Oh well, perhaps it's time to finally get those tracehooks implemented.

For now, please feel free to add

Acked-by: Havard Skinnemoen <hskinnemoen@...il.com>

to the two patches Matt sent earlier. I think they move things in the
right direction even though there are other issues that need to be
fixed as well.

Havard
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