linux-kernel - Re: [PATCH 14/14] ptrace: remove the extra wake_up_process() from ptrace

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Message-ID: <4CF3B0C8.7080200@kernel.org>
Date:	Mon, 29 Nov 2010 14:55:20 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	roland@...hat.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	"@sisk.plpavel@....cz"@htj.dyndns.org,
	"Jan Kratochvil \"" <jan.kratochvil@...hat.com>
Subject: Re: [PATCH 14/14] ptrace: remove the extra wake_up_process() from
 ptrace_detach()

Hello,

On 11/28/2010 09:44 PM, Oleg Nesterov wrote:
> Today I lost the concentration at 13/14 ;)
> 
> Will continue tomorrow. As for this patch,

Eh, well, you've already found enough holes in the patchset.  It's
like a swiss cheese.  I'll update and repost.

> On 11/26, Tejun Heo wrote:
>>
>> This wake_up_process() has a turbulent history.  This is a remnant
>> from ancient ptrace implementation and patently wrong.  Commit
>> 95a3540d (ptrace_detach: the wrong wakeup breaks the ERESTARTxxx
>> logic) removed it
> 
> Yes. This obviously means I personally like this change. In fact,
> I never understood this wakeup, and I was glad to find the reason
> to send the patch.

Another thing is that the use of wake_up_process() in ptrace is rather
scary even in ptrace_resume().  It will wake up even uninterruptible
sleeps.  Is there any reason it's not just waking up
TASK_INTERRUPTIBLE | STOPPED | TRACED?

Thanks.

-- 
tejun
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