On Saturday, December 12, 2015 12:21:43 AM Rafael J. Wysocki wrote:
> On Friday, December 11, 2015 05:47:08 PM Imre Deak wrote:
> > On pe, 2015-12-11 at 16:40 +0100, Rafael J. Wysocki wrote:
> > > On Friday, December 11, 2015 02:54:45 PM Imre Deak wrote:
> > > > On to, 2015-12-10 at 23:14 +0100, Rafael J. Wysocki wrote:
> > > > > On Thursday, December 10, 2015 11:20:40 PM Imre Deak wrote:
> > > > > > On Thu, 2015-12-10 at 22:42 +0100, Rafael J. Wysocki wrote:
> > > > > > > On Thursday, December 10, 2015 10:36:37 PM Rafael J. Wysocki
[cut]
>
> Yes, my suggested function can be written like this:
>
> bool pm_runtime_get_if_active(struct device *dev)
> {
> unsigned log flags;
> bool ret = false;
>
> spin_lock_irqsave(&dev->power.lock, flags);
>
> if (dev->power.runtime_status == RPM_ACTIVE) {
> if (atomic_inc_return(&dev->power.usage_count) > 1)
> ret = true;
> else
> atomic_dec(&dev->power.usage_count);
> }
>
> spin_unlock_irqrestore(&dev->power.lock, flags);
> return ret;
> }
>
> but this is obviously racy with respect to anyone concurrently changing the
> usage counter.
Somethng like this would be slightly more efficient:
bool pm_runtime_get_if_in_use(struct device *dev)
{
unsigned log flags;
bool ret = false;
spin_lock_irqsave(&dev->power.lock, flags);
if (dev->power.runtime_status == RPM_ACTIVE)
ret = !!atomic_inc_not_zero(&dev->power.usage_count);
spin_unlock_irqrestore(&dev->power.lock, flags);
return ret;
}
Thanks,
Rafael
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