From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Thompson Subject: Re: [PATCH v2 2/4] dmaengine: Add STM32 DMA driver Date: Wed, 14 Oct 2015 16:28:23 +0100 Message-ID: <561E7497.1050105@linaro.org> References: <1444745127-1105-1-git-send-email-cedric.madianga@gmail.com> <1444745127-1105-3-git-send-email-cedric.madianga@gmail.com> <561D1689.90703@linaro.org> <561E58AC.80207@linaro.org> <561E658D.1070900@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: M'boumba Cedric Madianga Cc: Maxime Coquelin , robh+dt@kernel.org, pawel.moll@arm.com, Mark Rutland , ijc+devicetree@hellion.org.uk, Kumar Gala , linux@arm.linux.org.uk, Vinod Koul , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org List-Id: devicetree@vger.kernel.org On 14/10/15 16:26, M'boumba Cedric Madianga wrote: > 2015-10-14 16:24 GMT+02:00 Daniel Thompson : >> >> 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. Daniel.