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

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Message-ID: <5154EAE6.6010106@oracle.com>
Date:	Thu, 28 Mar 2013 21:14:14 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Michel Lespinasse <walken@...gle.com>
CC:	Rik van Riel <riel@...riel.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 03/28/2013 09:00 PM, Michel Lespinasse wrote:
> 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>

And the warnings are gone:

	Tested-by: Sasha Levin <sasha.levin@...cle.com>


Thanks,
Sasha
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