From patchwork Thu Jul 14 02:57:56 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 9228845 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 D0AEB60572 for ; Thu, 14 Jul 2016 02:58:07 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C5C012808C for ; Thu, 14 Jul 2016 02:58:07 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BA96E280DE; Thu, 14 Jul 2016 02:58:07 +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=unavailable 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 C6476280B0 for ; Thu, 14 Jul 2016 02:58:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751208AbcGNC6F (ORCPT ); Wed, 13 Jul 2016 22:58:05 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:58012 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751174AbcGNC6D (ORCPT ); Wed, 13 Jul 2016 22:58:03 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 2C4EF611C4; Thu, 14 Jul 2016 02:58:03 +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 D362561154; Thu, 14 Jul 2016 02:58:01 +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] dmaengine: qcom_hidma: release the descriptor before the callback Date: Wed, 13 Jul 2016 22:57:56 -0400 Message-Id: <1468465076-27324-1-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 | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c index 41b5c6d..c41696e 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; @@ -122,28 +123,31 @@ 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) { - enum dma_status llstat; + list_for_each_entry_safe(mdesc, next, &list, node) { + dma_async_tx_callback callback; + void *param; desc = &mdesc->desc; spin_lock_irqsave(&mchan->lock, irqflags); - dma_cookie_complete(desc); + if (hidma_ll_status(mdma->lldev, mdesc->tre_ch) + == DMA_COMPLETE) + dma_cookie_complete(desc); 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) + callback(param); + } } /*