From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: subtle pm_runtime_put_sync race and sdio functions
Date: Sun, 26 Dec 2010 19:37:21 +0100
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To: Ohad Ben-Cohen <ohad@wizery.com>
Cc: linux-wireless@vger.kernel.org, linux-mmc@vger.kernel.org, Ido Yariv <ido@wizery.com>, linux-pm@lists.linux-foundation.org, Johannes Berg <johannes@sipsolutions.net>
List-Id: linux-pm@vger.kernel.org

On Sunday, December 26, 2010, Ohad Ben-Cohen wrote:
> On Sun, Dec 26, 2010 at 1:45 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > (It still is not a race, though.)
> 
> Thread 1
> =======
> 
> suspend_handler_of_a_random_device()
> {
>     return failure;
> }
> 
> Thread 2
> =======
> 
> suspend_handler_of_our_mmc_host_controller()
> {
>     invoke our sdio suspend handler and power down the card (directly);
>     return success;
> }
> 
> If thread 2 wins => everything is cool
> If thread 1 wins => our driver will not be able to resume
> 
> The race begins after mac80211 invokes our driver's power off handler,
> which is using pm_runtime_put_sync().

So, it only happens during asynchronous suspend?  In other words, if suspend
is synchronous, everything should be fine, right?

Rafael