linux-kernel - Re: [PATCH 16/16] ptrace: remove the extra wake_up_process() from ptrace

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Message-ID: <4CFE39EC.40907@kernel.org>
Date:	Tue, 07 Dec 2010 14:43:08 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Roland McGrath <roland@...hat.com>
CC:	oleg@...hat.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	rjw@...k.pl, jan.kratochvil@...hat.com
Subject: Re: [PATCH 16/16] ptrace: remove the extra wake_up_process() from
 ptrace_detach()

Hello, Roland.

On 12/07/2010 01:10 AM, Roland McGrath wrote:
> The plain wake_up_process was certainly wrong from the beginning.
> 
> We were conservative about changing it because of the difficulty of
> chasing all the corners where userland debuggers' behavior might be
> made to regress when it had been reliable in practice before (even
> if not always in theory, such as possible races that didn't bite in
> reality).  The userland code has gone to many contortions to cope
> with how the kernel behaved in the past, whether or not that
> behavior ever made any good sense.
> 
> For that sort of reason, none of this stuff should change at all in
> a -stable kernel, nor late in a release cycle.

Sure, definitely.  All these changes are at the earliest for the next
merge window.

> For new kernels, I think changing the behavior in the direction of
> something that can actually be described is OK as long as userland
> debugger maintainers like Jan agree to the new behavior and that the
> behavior really and truly does follow an articulated set of rules
> that the kernel and userland sides agree to.

Yeap, that sounds good to me.

Thanks.

-- 
tejun
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