linux-kernel - Re: [RFC PATCH] set TASK_TRACED before arch

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Date:	Thu, 5 Jun 2008 09:49:42 +0800
From:	"Luming Yu" <luming.yu@...il.com>
To:	"Petr Tesarik" <ptesarik@...e.cz>
Cc:	"Roland McGrath" <roland@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-ia64@...r.kernel.org
Subject: Re: [RFC PATCH] set TASK_TRACED before arch_ptrace code to fix a race

On Wed, Jun 4, 2008 at 5:16 PM, Petr Tesarik <ptesarik@...e.cz> wrote:
> Luming Yu wrote:
>>> It's definitely a bug in strace. For some reason (I don't care about)
>>> the execve() syscall produces an extra notification. However, this
>>> notification message is suppressed when SIGTRAP is blocked. This
>>> explains why the test case fails only when SIGTRAP is blocked.
>>
>> This is exact problem I suspected and I was trying to address in my hack..
>> Since there are several processes involved in the pretty complex
>> ptrace scenario.,
>> I need to capture all processes context with kdump to confirm this is
>> exact root-cause
>> for the problem. But kdump doesn't work for me..I'm trying to solve it now..
>>
>> I'm also in doubt about the semantic correctness of the test case..
>> Since SIGTRAP is so necessary to get ptrace work, is it legitimate to
>> block it in test case?
>>
>> One more thing I need to say is:
>> Same strace works for utrace enabled kernel on IA64.. If the bug is in
>> strace, how could it happen?
>
> No idea, but send me the strace.log file from running
>
> strace -o strace.log strace -f -o log.txt ./test1
>
> and I may be able to tell.

Please check the attachment!

>
> Petr Tesarik
>

Download attachment "strace.log" of type "application/octet-stream" (16090 bytes)