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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF336C6FA83 for ; Sat, 10 Sep 2022 21:26:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229969AbiIJV0U (ORCPT ); Sat, 10 Sep 2022 17:26:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229920AbiIJVYW (ORCPT ); Sat, 10 Sep 2022 17:24:22 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B40B050720; Sat, 10 Sep 2022 14:20:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6173BB80950; Sat, 10 Sep 2022 21:19:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE493C43145; Sat, 10 Sep 2022 21:19:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662844744; bh=SX8ctfDoXZyy93CaTDmVcLfuc2fkCYRrEUR7A5GxBqk=; h=From:To:Cc:Subject:Date:From; b=BVx/xF9yeoZ6aDZ5MkMfPRpLyBLQEjwMnU7Bwh0jQtqFddPG0zlnb9zMY6j2+patJ 1Arvuvf6J2Z72FWLLwfWqIxkQngFGNkiaKMxGXX8dqM8hqCCLbm+UJW7SRlq1Bimo2 NNGOa3c/B29Z/Umt14F0orrmMAl/AwVwbNf9S9q/jpesmAfVZzhv6TAguS8eFmSumV 5r7wVT0OXxedu4PigyeBwGmm/uG40YUWg1nwpWIEAafUKUmP3mn6Rqk2uGgrBUJFRC SpDZvcCaizWJ8QAX1bZp2XHRz+QOM2v1/UU3sFkDCyp9hBX+EWMopbUcx0bWB6QAoJ P00oeUA5+vyLg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Rob Clark , Sasha Levin , robdclark@gmail.com, quic_abhinavk@quicinc.com, dmitry.baryshkov@linaro.org, airlied@linux.ie, daniel@ffwll.ch, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.4 01/10] drm/msm/rd: Fix FIFO-full deadlock Date: Sat, 10 Sep 2022 17:18:52 -0400 Message-Id: <20220910211901.70760-1-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rob Clark [ Upstream commit 174974d8463b77c2b4065e98513adb204e64de7d ] If the previous thing cat'ing $debugfs/rd left the FIFO full, then subsequent open could deadlock in rd_write() (because open is blocked, not giving a chance for read() to consume any data in the FIFO). Also it is generally a good idea to clear out old data from the FIFO. Signed-off-by: Rob Clark Patchwork: https://patchwork.freedesktop.org/patch/496706/ Link: https://lore.kernel.org/r/20220807160901.2353471-2-robdclark@gmail.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/msm/msm_rd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/msm/msm_rd.c b/drivers/gpu/drm/msm/msm_rd.c index c7832a951039f..a6b024b06b363 100644 --- a/drivers/gpu/drm/msm/msm_rd.c +++ b/drivers/gpu/drm/msm/msm_rd.c @@ -191,6 +191,9 @@ static int rd_open(struct inode *inode, struct file *file) file->private_data = rd; rd->open = true; + /* Reset fifo to clear any previously unread data: */ + rd->fifo.head = rd->fifo.tail = 0; + /* the parsing tools need to know gpu-id to know which * register database to load. */ -- 2.35.1