linux-kernel - Re: [PATCH -mm -next] ipc,sem: untangle RCU locking with find_alloc

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Message-ID: <CANN689E30ORoTO75Xr=AknoHy+1ts7awi=4a3Jef31L6M2gMdQ@mail.gmail.com>
Date:	Thu, 28 Mar 2013 18:00:52 -0700
From:	Michel Lespinasse <walken@...gle.com>
To:	Rik van Riel <riel@...riel.com>
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	torvalds@...ux-foundation.org, davidlohr.bueso@...com,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	hhuang@...hat.com, jason.low2@...com, lwoodman@...hat.com,
	chegu_vinod@...com, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH -mm -next] ipc,sem: untangle RCU locking with find_alloc_undo

On Thu, Mar 28, 2013 at 8:32 AM, Rik van Riel <riel@...riel.com> wrote:
> The ipc semaphore code has a nasty RCU locking tangle, with both
> find_alloc_undo and semtimedop taking the rcu_read_lock(). The
> code can be cleaned up somewhat by only taking the rcu_read_lock
> once.
>
> The only caller of find_alloc_undo is in semtimedop.
>
> This should solve the trinity issue reported by Sasha Levin.
>
> Reported-by: Sasha Levin <sasha.levin@...cle.com>
> Signed-off-by: Rik van Riel <riel@...hat.com>

Looks good^Wbetter. I have nothing specific to say other than I've
been staring at it for 10 minutes :)

Reviewed-by: Michel Lespinasse <walken@...gle.com>

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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