From patchwork Sun Jul 31 14:11:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 9253379 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0574C6077C for ; Sun, 31 Jul 2016 14:11:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EAF4628489 for ; Sun, 31 Jul 2016 14:11:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DE6FF2848E; Sun, 31 Jul 2016 14:11:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CD0AA28489 for ; Sun, 31 Jul 2016 14:11:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753096AbcGaOLP (ORCPT ); Sun, 31 Jul 2016 10:11:15 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:34996 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752822AbcGaOLO (ORCPT ); Sun, 31 Jul 2016 10:11:14 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 5342461208; Sun, 31 Jul 2016 14:11:13 +0000 (UTC) Received: from drakthul.qualcomm.com (global_nat1_iad_fw.qualcomm.com [129.46.232.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: okaya@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 19950611BE; Sun, 31 Jul 2016 14:11:12 +0000 (UTC) From: Sinan Kaya To: dmaengine@vger.kernel.org, timur@codeaurora.org, cov@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , linux-kernel@vger.kernel.org Subject: [PATCH V2] dmaengine: qcom_hidma: release the descriptor before the callback Date: Sun, 31 Jul 2016 10:11:06 -0400 Message-Id: <1469974266-28023-1-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c index 41b5c6d..4aaceab 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 +123,10 @@ 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; + dma_async_tx_callback callback; + void *param; desc = &mdesc->desc; @@ -132,18 +135,19 @@ 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 (desc->callback && (llstat == DMA_COMPLETE)) - desc->callback(desc->callback_param); + callback = desc->callback; + param = desc->callback_param; 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 (callback && (llstat == DMA_COMPLETE)) + callback(param); + } } /*