From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964978AbcHaPLA (ORCPT ); Wed, 31 Aug 2016 11:11:00 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:38538 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964814AbcHaPK5 (ORCPT ); Wed, 31 Aug 2016 11:10:57 -0400 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org 5DE4E613A6 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=okaya@codeaurora.org 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 , Andy Shevchenko , Dave Jiang , Lars-Peter Clausen , linux-kernel@vger.kernel.org Subject: [PATCH V4 1/3] dmaengine: qcom_hidma: release the descriptor before the callback Date: Wed, 31 Aug 2016 11:10:27 -0400 Message-Id: <1472656229-12955-2-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1472656229-12955-1-git-send-email-okaya@codeaurora.org> References: <1472656229-12955-1-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); + } } /* -- 1.9.1