linux-kernel - Re: serial percpu_ref draining in exit

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Message-ID: <x49619vts57.fsf@segfault.boston.devel.redhat.com>
Date:	Fri, 20 Mar 2015 14:56:04 -0400
From:	Jeff Moyer <jmoyer@...hat.com>
To:	Jens Axboe <axboe@...nel.dk>
Cc:	Tejun Heo <tj@...nel.org>, kent.overstreet@...il.com,
	Benjamin LaHaise <bcrl@...ck.org>, linux-kernel@...r.kernel.org
Subject: Re: serial percpu_ref draining in exit_aio()

Jens Axboe <axboe@...nel.dk> writes:

> On 03/19/2015 03:27 PM, Jens Axboe wrote:
>> On 03/19/2015 03:00 PM, Tejun Heo wrote:
>>> On Thu, Mar 19, 2015 at 04:58:33PM -0400, Jeff Moyer wrote:
>>>> Do you really want to do memory allocation in the exit path?  That
>>>> sounds like a bad idea to me.  (Of course, now you're going to point out
>>>> all the places that currently happens, right?  ;-)
>>>
>>> I think we just need a counter there - let everyone count down as they
>>> exit and the last one trigger the completion, no?
>>
>> Yeah that's a good point, that'd be cleaner too. I'll change it and test
>> that.
>
> Here's a cleaner variant that pairs the completion even with an atomic
> count. Works for me as well.

I like this version.  I ran it though the libaio test harness and
xfstests aio tests and it passed.

Thanks, Jens!

Reviewed-by: Jeff Moyer <jmoyer@...hat.com>
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