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 3F629C6FA82 for ; Sat, 10 Sep 2022 21:27:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231354AbiIJV1x (ORCPT ); Sat, 10 Sep 2022 17:27:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231217AbiIJV1f (ORCPT ); Sat, 10 Sep 2022 17:27:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B48C54F6A2; Sat, 10 Sep 2022 14:22:01 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 1F1CF60EB8; Sat, 10 Sep 2022 21:19:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52419C433D6; Sat, 10 Sep 2022 21:19:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662844790; bh=jyz0fgXTdZdiAhc3Zipbr3ICrBDxV/WPhd/zQrtwP6I=; h=From:To:Cc:Subject:Date:From; b=d9lTTFUbx1tP//LYNQ+iRTQEj1wOZW55uAeSbpL3IHCv2+0tv/tHVo1I6Os6WUx2w WhsRBNUE2xPYTfGJ4isuG9wXPNCIWCBHh3CzwbsamIb0rv3/Ifsg/epSMWV+Spje9c bNKhvHp89AYugxlOIYX8y6HSQJYAQOC5LLj3eOepUqyGhr/DZhMNXc+XZA7NYObvR1 5xYHEDs+WVB1KgSS2EAiBdIq7mPJJjPLfJEdn0l0xRJI6U9mzyY3AhhOuowXL/Ck2t ITx/pKqc0SOc3cjDdttkg/S55nrOdtIf9jNCdfmEHH/TD4/GVniUytKpI3UVdKur8E zuON355tk10UQ== 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 4.9 1/5] drm/msm/rd: Fix FIFO-full deadlock Date: Sat, 10 Sep 2022 17:19:43 -0400 Message-Id: <20220910211947.71066-1-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 4823019eb422b..a8a04d8c5ca62 100644 --- a/drivers/gpu/drm/msm/msm_rd.c +++ b/drivers/gpu/drm/msm/msm_rd.c @@ -188,6 +188,9 @@ 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