Re: ipc msg now works (was Re: ipc-msg broken again on 3.11-rc7?)

From: Sedat Dilek
Date: Tue Sep 03 2013 - 18:46:56 EST


On Tue, Sep 3, 2013 at 12:32 PM, Vineet Gupta
<Vineet.Gupta1@xxxxxxxxxxxx> wrote:
> On 09/03/2013 03:47 PM, Manfred Spraul wrote:
>> Hi Vineet,
>>
>> On 09/03/2013 11:51 AM, Vineet Gupta wrote:
>>> On 09/03/2013 02:53 PM, Manfred Spraul wrote:
>>>> The access to msq->q_cbytes is not protected.
>>>>
>>>> Vineet, could you try to move the test for free space after ipc_lock?
>>>> I.e. the lock must not get dropped between testing for free space and
>>>> enqueueing the messages.
>>> Hmm, the code movement is not trivial. I broke even the simplest of cases (patch
>>> attached). This includes the additional change which Linus/Davidlohr had asked for.
>> The attached patch should work. Could you try it?
>>
>
> Yes this did the trick, now the default config of 100k iterations + 16 processes
> runs to completion.
>

Manfred's patch "ipc/msg.c: Fix lost wakeup in msgsnd()." is now upstream.

- Sedat -

[1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bebcb928c820d0ee83aca4b192adc195e43e66a2
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