From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH V2] dma: tegra: avoid channel lock up after free Date: Tue, 30 Oct 2012 12:05:27 -0600 Message-ID: <509016E7.800@wwwdotorg.org> References: <508EA04D.5050805@wwwdotorg.org> <1351552833-4132-1-git-send-email-digetx@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1351552833-4132-1-git-send-email-digetx@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , ldewangan@nvidia.com Cc: vinod.koul@intel.com, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-tegra@vger.kernel.org On 10/29/2012 05:20 PM, Dmitry Osipenko wrote: > Fixed channel "lock up" after free. > > Lock scenario: Channel 1 was allocated and prepared as slave_sg, used and freed. > Now preparation of cyclic dma on channel 1 will fail with err "DMA configuration > conflict" because tdc->isr_handler still selected to handle_once_dma_done. > > This happens because tegra_dma_abort_all() won't be called on channel freeing > if pending list is empty or channel not busy. We need to clear isr_handler > on channel freeing to avoid locking. Also I added small optimization to prepare > functions, so current channel type checked before making allocations. Reviewed-by: Stephen Warren I believe this looks OK. However, I would like Laxman to also ack/review this since he wrote the driver.