On 30.04.2020 13:34, Andy Shevchenko wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
>
> On Thu, Apr 30, 2020 at 07:59:41AM +0000, [email protected] wrote:
>>
>>
>> On 27.04.2020 13:51, Andy Shevchenko wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
>>> content is safe
>>>
>>> The commit e6a41c23df0d, while trying to fix an issue,
>>>
>>> ("net: macb: ensure interface is not suspended on at91rm9200")
>>>
>>> introduced a refcounting regression, because in error case refcounter
>>> must be balanced. Fix it by calling pm_runtime_put_noidle() in error case.
>>>
>>> While here, fix the same mistake in other couple of places.
>
> ...
>
>>> status = pm_runtime_get_sync(&bp->pdev->dev);
>>> - if (status < 0)
>>> + if (status < 0) {
>>> + pm_runtime_put_noidle(&bp->pdev->dev);
>>
>> pm_runtime_get_sync() calls __pm_runtime_resume(dev, RPM_GET_PUT),
>> increment refcounter and resume the device calling rpm_resume().
>
> Read the code further than the header file, please.
>
>> pm_runtime_put_noidle() just decrement the refcounter.
>
> which is exactly what has to be done on error path.
>
>> The proper way,
>> should be calling suspend again if the operation fails as
>> pm_runtime_put_autosuspend() does. So, what the code under mdio_pm_exit
>> label does should be enough.
>
> Huh? It returns an error without rebalancing refcounter.
Yep, my mistake. Your code is good.
>
> Yeah, one more time an evidence that people do not get runtime PM properly.>
>>> goto mdio_pm_exit;
>>> + }
>>>
>>> status = macb_mdio_wait_for_idle(bp);
>>> if (status < 0)
>>> @@ -386,8 +388,10 @@ static int macb_mdio_write(struct mii_bus *bus, int
>>> mii_id, int regnum,
>>> int status;
>>>
>>> status = pm_runtime_get_sync(&bp->pdev->dev);
>>> - if (status < 0)
>>> + if (status < 0) {
>>> + pm_runtime_put_noidle(&bp->pdev->dev);
>>
>> Ditto.
>
> Ditto.
>
>>
>>> goto mdio_pm_exit;
>>> + }
>>>
>>> status = macb_mdio_wait_for_idle(bp);
>>> if (status < 0)
>>> @@ -3816,8 +3820,10 @@ static int at91ether_open(struct net_device *dev)
>>> int ret;
>>>
>>> ret = pm_runtime_get_sync(&lp->pdev->dev);
>>> - if (ret < 0)
>>> + if (ret < 0) {
>>> + pm_runtime_put_noidle(&lp->pdev->dev);
>>
>> The proper way should be calling pm_runtime_put_sync() not only for this
>> returning path but for all of them in this function.
>
> Of course not.
>
>>> return ret;
>>> + }
>>>
>>> /* Clear internal statistics */
>>> ctl = macb_readl(lp, NCR);
>>> --
>>> 2.26.2
>>>
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
