From nobody Sun Apr 5 18:17:07 2026 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 DFBBCECAAD8 for ; Fri, 16 Sep 2022 10:08:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230111AbiIPKIt (ORCPT ); Fri, 16 Sep 2022 06:08:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231128AbiIPKIO (ORCPT ); Fri, 16 Sep 2022 06:08:14 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D6C8AB4C9; Fri, 16 Sep 2022 03:08:02 -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 ams.source.kernel.org (Postfix) with ESMTPS id CE89DB8250C; Fri, 16 Sep 2022 10:08:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D0F2C433C1; Fri, 16 Sep 2022 10:07:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663322879; bh=2HvLPQ0g5T8ddpdD+yRBeKrwMCuKVLDYV2jEiR1DsAI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bGDAQleJx3/W13OVcLQqBZopZ7DrK52s7k8Sfe4PvHx0ddgOPRm6VknXiu7F2R40v H5ktP/CgEdskDhYgdJe+MNZVeNGCImfmNF9LMQVq1q9ykOZQBKVvAzUVGMBQYFCwWu kvHXnkvicKW5UNR7g6tK/Bgk0Smi0N9RwzVGWYBQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rob Clark , Sasha Levin Subject: [PATCH 4.14 2/7] drm/msm/rd: Fix FIFO-full deadlock Date: Fri, 16 Sep 2022 12:07:54 +0200 Message-Id: <20220916100441.657588409@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220916100441.528608977@linuxfoundation.org> References: <20220916100441.528608977@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 bdce1c9434c6c..54891cbf4f50f 100644 --- a/drivers/gpu/drm/msm/msm_rd.c +++ b/drivers/gpu/drm/msm/msm_rd.c @@ -193,6 +193,9 @@ static int rd_open(struct inode *inode, struct file *fi= le) file->private_data =3D rd; rd->open =3D true; =20 + /* Reset fifo to clear any previously unread data: */ + rd->fifo.head =3D rd->fifo.tail =3D 0; + /* the parsing tools need to know gpu-id to know which * register database to load. */ --=20 2.35.1