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 0EAECECAAD8 for ; Fri, 16 Sep 2022 10:11:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231134AbiIPKLb (ORCPT ); Fri, 16 Sep 2022 06:11:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230157AbiIPKKe (ORCPT ); Fri, 16 Sep 2022 06:10:34 -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 27CEEAC265; Fri, 16 Sep 2022 03:09:02 -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 332A7629FD; Fri, 16 Sep 2022 10:09:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3472EC433D6; Fri, 16 Sep 2022 10:09:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663322940; bh=SX8ctfDoXZyy93CaTDmVcLfuc2fkCYRrEUR7A5GxBqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y58p6FPVFedZ8DM3+5xu0Ci5GmOTz7TmgdMzCLHT85ys1ydtm+p4ht0Nf6lZsXxcm +SNjl7eknXeuxCjdAcX3AMvefMc043ROtro0T2X2EfXfpkBJB3GkKFDXcc//CwZiPN 5ZRr5Yqp2rFakeycDYeHuo42JNxLRNGVxjl8vq1s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rob Clark , Sasha Levin Subject: [PATCH 5.4 01/14] drm/msm/rd: Fix FIFO-full deadlock Date: Fri, 16 Sep 2022 12:08:08 +0200 Message-Id: <20220916100443.200072026@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220916100443.123226979@linuxfoundation.org> References: <20220916100443.123226979@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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