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 B3811C3F6B0 for ; Thu, 25 Aug 2022 01:44:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229463AbiHYBos (ORCPT ); Wed, 24 Aug 2022 21:44:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39562 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235780AbiHYBoF (ORCPT ); Wed, 24 Aug 2022 21:44:05 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06F0A9AFBD; Wed, 24 Aug 2022 18:39:41 -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 5A488B826C8; Thu, 25 Aug 2022 01:39:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CD41C433B5; Thu, 25 Aug 2022 01:39:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661391576; bh=Si1aPxgcvJy78GQs4fgXZOdxEB0Ayzx9ujfRXTCW+Qk=; h=From:To:Cc:Subject:Date:From; b=nGdrozcQEP/Rl4lVYWKw42J2h3ibYjGbkhTtOqGRPzysnxH4fS0mfxU63V6TF+42O OcAePGU0JgFCc7k/nwZB6ZzxU3uD/OfK2NMUlmc4KaddlD5iBOayp2NYNvFKYB923h yAYjvl85I6a/UN0EGnXHN9a/jDjWJyZUv1WDEgqtrPKj0gMadfcwZ/QcxvNRejP5Lp nAOpQOd11Kba5Vo5R+TLJGpU2aSaUNWGp8/QA4f87qIy3IUwII4JPbYKAPREzDE6dA eqgv6pas2vP954x0yQXlZDjey+Edz+jJOlYHHaj4Gny3npeyASwHs3fXZFdDfq1eP3 YViNawQzXN9wQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Josip Pavic , Jun Lei , Alex Hung , Aric Cyr , Daniel Wheeler , Alex Deucher , Sasha Levin , harry.wentland@amd.com, sunpeng.li@amd.com, Rodrigo.Siqueira@amd.com, christian.koenig@amd.com, Xinhui.Pan@amd.com, airlied@linux.ie, daniel@ffwll.ch, chiahsuan.chung@amd.com, jiapeng.chong@linux.alibaba.com, isabbasso@riseup.net, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.4 1/8] drm/amd/display: Avoid MPC infinite loop Date: Wed, 24 Aug 2022 21:39:20 -0400 Message-Id: <20220825013932.23467-1-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: linux-kernel@vger.kernel.org From: Josip Pavic [ Upstream commit 8de297dc046c180651c0500f8611663ae1c3828a ] [why] In some cases MPC tree bottom pipe ends up point to itself. This causes iterating from top to bottom to hang the system in an infinite loop. [how] When looping to next MPC bottom pipe, check that the pointer is not same as current to avoid infinite loop. Reviewed-by: Josip Pavic Reviewed-by: Jun Lei Acked-by: Alex Hung Signed-off-by: Aric Cyr Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c | 6 ++++++ drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c index 8b2f29f6dabd..068e79fa3490 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c @@ -118,6 +118,12 @@ struct mpcc *mpc1_get_mpcc_for_dpp(struct mpc_tree *tree, int dpp_id) while (tmp_mpcc != NULL) { if (tmp_mpcc->dpp_id == dpp_id) return tmp_mpcc; + + /* avoid circular linked list */ + ASSERT(tmp_mpcc != tmp_mpcc->mpcc_bot); + if (tmp_mpcc == tmp_mpcc->mpcc_bot) + break; + tmp_mpcc = tmp_mpcc->mpcc_bot; } return NULL; diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c index 5a188b2bc033..0a00bd8e00ab 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c @@ -488,6 +488,12 @@ struct mpcc *mpc2_get_mpcc_for_dpp(struct mpc_tree *tree, int dpp_id) while (tmp_mpcc != NULL) { if (tmp_mpcc->dpp_id == 0xf || tmp_mpcc->dpp_id == dpp_id) return tmp_mpcc; + + /* avoid circular linked list */ + ASSERT(tmp_mpcc != tmp_mpcc->mpcc_bot); + if (tmp_mpcc == tmp_mpcc->mpcc_bot) + break; + tmp_mpcc = tmp_mpcc->mpcc_bot; } return NULL; -- 2.35.1