Re: [linux-pm] subtle pm_runtime_put_sync race and sdio functions

["Rafael J. Wysocki" <rjw@sisk.pl>]

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