linux-kernel - Re: [PATCH v2 2/4] dmaengine: Add STM32 DMA driver

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Message-ID: <CAOAejn0chZD5mgi8WrW3ow3APUHTJOYP4=G2jCZ_Po4qe9eACw@mail.gmail.com>
Date:	Wed, 14 Oct 2015 17:41:26 +0200
From:	"M'boumba Cedric Madianga" <cedric.madianga@...il.com>
To:	Daniel Thompson <daniel.thompson@...aro.org>
Cc:	Maxime Coquelin <mcoquelin.stm32@...il.com>, robh+dt@...nel.org,
	pawel.moll@....com, Mark Rutland <mark.rutland@....com>,
	ijc+devicetree@...lion.org.uk, Kumar Gala <galak@...eaurora.org>,
	linux@....linux.org.uk, Vinod Koul <vinod.koul@...el.com>,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org
Subject: Re: [PATCH v2 2/4] dmaengine: Add STM32 DMA driver

2015-10-14 17:28 GMT+02:00 Daniel Thompson <daniel.thompson@...aro.org>:
> On 14/10/15 16:26, M'boumba Cedric Madianga wrote:
>>
>> 2015-10-14 16:24 GMT+02:00 Daniel Thompson <daniel.thompson@...aro.org>:
>>>
>>>
>>> Hmnnn...
>>>
>>> The dmaengine framework will WARN_ONCE() if an dmaengine is removed
>>> whilst
>>> it is active and also works hard to ensure dmaengine modules are not
>>> removed
>>> whilst there are active drivers using the framework.
>>>
>>> How do we get into this function whilst there is still an active DMA
>>> channels?
>>
>>
>> For example, when a user try "rmmod stm32-dma" in uart console.
>> It will enter in stm32_dma_remove while there is potentially still active
>> DMA.
>
>
> Check dmaengine.c for yourself but I think in this case the dmaengine
> framework will hold references to the module and prevent the remove from
> taking place.

Yes I did it.
As far I understand, the dmaengine framework will print a warning
message but doesn't stop removing operation if there are some active
clients.

Cedric.
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