linux-kernel - Re: [PATCH 3/3] signal: do_sigtimedwait() needs retarget_shared

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Message-ID: <20110426114251.3d85eec8@mfleming-mobl1.ger.corp.intel.com>
Date:	Tue, 26 Apr 2011 11:42:51 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>,
	"Nikita V. Youshchenko" <nyoushchenko@...sta.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] signal: do_sigtimedwait() needs
 retarget_shared_pending()

On Sat, 23 Apr 2011 20:00:00 +0200
Oleg Nesterov <oleg@...hat.com> wrote:

> do_sigtimedwait() changes current->blocked and thus it needs
> set_current_bloked()->retarget_shared_pending().

If you do another version of this patch could you fix up the function
names in the commit log, s/set_current_bloked/set_current_blocked/ ? Or
maybe Andrew can fix it up if he pulls them into -mm.

> We could use set_current_bloked() directly. It is fine to change
> ->real_blocked from all-zeroes to ->blocked and vice versa lockless,
> but this is not immediately clear, looks racy, and needs a huge
> comment to explain why this is correct.
> 
> To keep the things simple this patch adds the new static helper,
> __set_task_blocked() which should be called with ->siglock held. This
> way we can change both ->real_blocked and ->blocked atomically under
> ->siglock as the current code does. This is more understandable.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Reviewed-by: Matt Fleming <matt.fleming@...ux.intel.com>

-- 
Matt Fleming, Intel Open Source Technology Center
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