From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932774AbcHWEsf (ORCPT ); Tue, 23 Aug 2016 00:48:35 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:50115 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932638AbcHWEsb (ORCPT ); Tue, 23 Aug 2016 00:48:31 -0400 From: Sinan Kaya To: dmaengine@vger.kernel.org, timur@codeaurora.org, cov@codeaurora.org, vinod.koul@intel.com, jcm@redhat.com Cc: agross@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , Dan Williams , Lars-Peter Clausen , Andy Shevchenko , Dave Jiang , linux-kernel@vger.kernel.org Subject: [PATCH V3 1/3] dmaengine: qcom_hidma: release the descriptor before the callback Date: Tue, 23 Aug 2016 00:48:09 -0400 Message-Id: <1471927691-28827-2-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1471927691-28827-1-git-send-email-okaya@codeaurora.org> References: <1471927691-28827-1-git-send-email-okaya@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a race condition between data transfer callback and descriptor free code. The callback routine may decide to clear the resources even though the descriptor has not yet been freed. Instead of calling the callback first and then releasing the memory, this code is changing the order to return the descriptor back to the free pool and then call the user provided callback. Signed-off-by: Sinan Kaya --- drivers/dma/qcom/hidma.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c index 1197fbf..b8493ba 100644 --- a/drivers/dma/qcom/hidma.c +++ b/drivers/dma/qcom/hidma.c @@ -111,6 +111,7 @@ static void hidma_process_completed(struct hidma_chan *mchan) struct dma_async_tx_descriptor *desc; dma_cookie_t last_cookie; struct hidma_desc *mdesc; + struct hidma_desc *next; unsigned long irqflags; struct list_head list; @@ -122,8 +123,9 @@ static void hidma_process_completed(struct hidma_chan *mchan) spin_unlock_irqrestore(&mchan->lock, irqflags); /* Execute callbacks and run dependencies */ - list_for_each_entry(mdesc, &list, node) { + list_for_each_entry_safe(mdesc, next, &list, node) { enum dma_status llstat; + struct dmaengine_desc_callback cb; desc = &mdesc->desc; @@ -132,18 +134,18 @@ static void hidma_process_completed(struct hidma_chan *mchan) spin_unlock_irqrestore(&mchan->lock, irqflags); llstat = hidma_ll_status(mdma->lldev, mdesc->tre_ch); - if (llstat == DMA_COMPLETE) - dmaengine_desc_get_callback_invoke(desc, NULL); + dmaengine_desc_get_callback(desc, &cb); last_cookie = desc->cookie; dma_run_dependencies(desc); - } - /* Free descriptors */ - spin_lock_irqsave(&mchan->lock, irqflags); - list_splice_tail_init(&list, &mchan->free); - spin_unlock_irqrestore(&mchan->lock, irqflags); + spin_lock_irqsave(&mchan->lock, irqflags); + list_move(&mdesc->node, &mchan->free); + spin_unlock_irqrestore(&mchan->lock, irqflags); + if (llstat == DMA_COMPLETE) + dmaengine_desc_callback_invoke(&cb, NULL); + } } /* -- 1.8.2.1