linux-kernel - Re: [PATCH 2/3] dmaengine: usb-dmac: Fix PM reference leak in usb_dmac

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Message-ID: <c8fcdaa1-f053-47aa-2dad-521b8f34b8d1@huawei.com>
Date:   Mon, 5 Jul 2021 16:41:39 +0800
From:   "yukuai (C)" <yukuai3@...wei.com>
To:     Vinod Koul <vkoul@...nel.org>, Johan Hovold <johan@...nel.org>
CC:     <mcoquelin.stm32@...il.com>, <alexandre.torgue@...s.st.com>,
        <michal.simek@...inx.com>, <dmaengine@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <yi.zhang@...wei.com>
Subject: Re: [PATCH 2/3] dmaengine: usb-dmac: Fix PM reference leak in
 usb_dmac_probe()

Hi, Vinod

Are you still intrested in accepting this patch?

Thanks,
Yu Kuai

On 2021/06/07 18:19, Vinod Koul wrote:
> On 07-06-21, 10:06, Johan Hovold wrote:
>> On Thu, Jun 03, 2021 at 04:39:08PM +0530, Vinod Koul wrote:
>>> On 31-05-21, 11:19, Johan Hovold wrote:
>>>> On Mon, May 31, 2021 at 02:27:34PM +0530, Vinod Koul wrote:
>>>>> On 31-05-21, 14:11, yukuai (C) wrote:
>>>>>> On 2021/05/31 12:00, Vinod Koul wrote:
>>>>>>> On 17-05-21, 16:18, Yu Kuai wrote:
>>>>>>>> pm_runtime_get_sync will increment pm usage counter even it failed.
>>>>>>>> Forgetting to putting operation will result in reference leak here.
>>>>>>>> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
>>>>>>>> counter balanced.
>>
>>>>> Yes the rumtime_pm is disabled on failure here and the count would have
>>>>> no consequence...
>>>>
>>>> You should still balance the PM usage counter as it isn't reset for
>>>> example when reloading the driver.
>>>
>>> Should I driver trust that on load PM usage counter is balanced and not
>>> to be reset..?
>>
>> Not sure what you're asking here. But a driver should never leave the PM
>> usage counter unbalanced.
> 
> Thinking about again, yes we should safely assume the counter is
> balanced when driver loads.. so unloading while balancing sounds better
> behaviour
> 
> Thanks
>