From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EF35C43603 for ; Tue, 10 Dec 2019 00:24:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25F8E208C3 for ; Tue, 10 Dec 2019 00:24:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727304AbfLJAYm (ORCPT ); Mon, 9 Dec 2019 19:24:42 -0500 Received: from ale.deltatee.com ([207.54.116.67]:38024 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726495AbfLJAYm (ORCPT ); Mon, 9 Dec 2019 19:24:42 -0500 Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1ieTKS-0002Cv-6h; Mon, 09 Dec 2019 17:24:41 -0700 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.92) (envelope-from ) id 1ieTKR-0000ll-5S; Mon, 09 Dec 2019 17:24:39 -0700 From: Logan Gunthorpe To: linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Vinod Koul Cc: Dan Williams , Kit Chow , Logan Gunthorpe Date: Mon, 9 Dec 2019 17:24:34 -0700 Message-Id: <20191210002437.2907-3-logang@deltatee.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191210002437.2907-1-logang@deltatee.com> References: <20191210002437.2907-1-logang@deltatee.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, vkoul@kernel.org, dan.j.williams@intel.com, kchow@gigaio.com, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [PATCH v2 2/5] dmaengine: Call module_put() after device_free_chan_resources() X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org The module reference is taken to ensure the callbacks still exist when they are called. If the channel holds the last reference to the module, the module can disappear before device_free_chan_resources() is called and would cause a call into free'd memory. Signed-off-by: Logan Gunthorpe --- drivers/dma/dmaengine.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 4b604086b1b3..776fdf535a3a 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -250,7 +250,6 @@ static void dma_chan_put(struct dma_chan *chan) return; chan->client_count--; - module_put(dma_chan_to_owner(chan)); /* This channel is not in use anymore, free it */ if (!chan->client_count && chan->device->device_free_chan_resources) { @@ -259,6 +258,8 @@ static void dma_chan_put(struct dma_chan *chan) chan->device->device_free_chan_resources(chan); } + module_put(dma_chan_to_owner(chan)); + /* If the channel is used via a DMA request router, free the mapping */ if (chan->router && chan->router->route_free) { chan->router->route_free(chan->router->dev, chan->route_data); -- 2.20.1