linux-kernel - Re: dmaengine: stm32-mdma: call pm_runtime_put if pm_runtime_get

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Date:   Thu, 4 Jun 2020 07:43:14 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Navid Emamdoost <navid.emamdoost@...il.com>,
        dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-stm32@...md-mailman.stormreply.com
Cc:     Alexandre Torgue <alexandre.torgue@...com>,
        Dan Williams <dan.j.williams@...el.com>,
        Navid Emamdoost <emamd001@....edu>, Kangjie Lu <kjlu@....edu>,
        Stephen McCamant <smccaman@....edu>,
        Qiushi Wu <wu000273@....edu>, Vinod Koul <vkoul@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: dmaengine: stm32-mdma: call pm_runtime_put if pm_runtime_get_sync
 fails

>>> Calling pm_runtime_get_sync increments the counter even in case of
>>> failure, causing incorrect ref count. Call pm_runtime_put if
>>> pm_runtime_get_sync fails.
>>
>> Is it appropriate to copy a sentence from the change description
>> into the patch subject?
>>
>> How do you think about a wording variant like the following?
>>
>>    The PM runtime reference counter is generally incremented by a call of
>>    the function “pm_runtime_get_sync”.
>>    Thus call the function “pm_runtime_put” also in two error cases
>>    to keep the reference counting consistent.
>
> IMHO the important part is "even in case of failure", which you dropped.
> Missing that point was the root cause of the issue being fixed.
> Hence I prefer the original description, FWIW.

Would you like to comment any more of the presented patch review concerns?

Can it make sense to combine any adjustments into a single patch
according to the discussed software transformation pattern?
https://lore.kernel.org/patchwork/project/lkml/list/?submitter=26544&state=*&q=engine%3A+stm32&archive=both

Regards,
Markus