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