From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 561C926D4EF for ; Tue, 29 Jul 2025 10:26:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753784799; cv=none; b=dW6XTqh7AYNvMMLt6jUSqwDUtNe1AUxkYgz584VNKozA9r9+CejqPAyn6oGZeaY+iGbQJo4VXPndU8CIhOLCnm6wLieejdAxVcThmB4LFCgw8Z29M/QRzvsaf5VOO80AeXi8DDmIjCCfqP8qLCw9NxYH2ifWsWN6AYnhCNTWx2o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753784799; c=relaxed/simple; bh=eOtAjkutcfTgfbsTp9YZ6t3LmyaglOAeVM+Ud2WX8gE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rH8Reoci3bm2FSd8+Zzny//h4cmXJZFK4j0OV1MREyWFxgQwd61gFtKfmvpGQJhv7bprhG9PazluX4YyA2+a3r1/FfUnkzs0vomGiSWf/ygIxlJYjskWaxn7Obk91otyrtp4M8Tl7aiHnBLRcqZ9Q78SjTbXpOSfZvQmZ3i4Bfc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=d19DDHnJ; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="d19DDHnJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1753784794; bh=eOtAjkutcfTgfbsTp9YZ6t3LmyaglOAeVM+Ud2WX8gE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=d19DDHnJYY4lXlvk7kWjbkvAlwGGfW/DR+TRQrOgBAKEbu8d59K9iyog18odLNH/d MWYHoP3lE8vm8KzH/oJj7ZwoY2/33e5+mwrdrMVMbQ4OuxAIkcPyhZo+YXGuQJdfAG JQJ7+t5beFEpbT7Q9zkzJ6x9SGjONFgoBASVhsCPAEf8jPo43OAv4/G94B1vgwLgvg qOlHU8taa5oXeZcC0J5TdyQHq7Tz7e2swZYi0sGHZUM1ux0NUvSVRpxcYg18rvFW7f qmEH9vrLwewjMmSaOq8eVQS6g5ZeD7BYSSwGmgVRJzY0AsV4T6GBOHe0ZsaivSAGT9 gFxMdntqqBn5A== Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id 7C92717E1315; Tue, 29 Jul 2025 12:26:33 +0200 (CEST) Message-ID: Date: Tue, 29 Jul 2025 12:26:32 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH] drm/mediatek: Add error handling for old state CRTC in atomic_disable To: Jason-JH Lin , Chun-Kuang Hu , David Airlie Cc: Philipp Zabel , Daniel Vetter , Matthias Brugger , Nancy Lin , Singo Chang , Paul-PL Chen , Yongqiang Niu , Zhenxing Qin , Xiandong Wang , Sirius Wang , Xavier Chang , Jarried Lin , Fei Shao , Chen-yu Tsai , linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Project_Global_Chrome_Upstream_Group@mediatek.com References: <20250728025036.24953-1-jason-jh.lin@mediatek.com> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20250728025036.24953-1-jason-jh.lin@mediatek.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Il 28/07/25 04:48, Jason-JH Lin ha scritto: > Introduce error handling to address an issue where, after a hotplug > event, the cursor continues to update. This situation can lead to a > kernel panic due to accessing the NULL `old_state->crtc`. > > E,g. > Unable to handle kernel NULL pointer dereference at virtual address > Call trace: > mtk_crtc_plane_disable+0x24/0x140 > mtk_plane_atomic_update+0x8c/0xa8 > drm_atomic_helper_commit_planes+0x114/0x2c8 > drm_atomic_helper_commit_tail_rpm+0x4c/0x158 > commit_tail+0xa0/0x168 > drm_atomic_helper_commit+0x110/0x120 > drm_atomic_commit+0x8c/0xe0 > drm_atomic_helper_update_plane+0xd4/0x128 > __setplane_atomic+0xcc/0x110 > drm_mode_cursor_common+0x250/0x440 > drm_mode_cursor_ioctl+0x44/0x70 > drm_ioctl+0x264/0x5d8 > __arm64_sys_ioctl+0xd8/0x510 > invoke_syscall+0x6c/0xe0 > do_el0_svc+0x68/0xe8 > el0_svc+0x34/0x60 > el0t_64_sync_handler+0x1c/0xf8 > el0t_64_sync+0x180/0x188 > > Adding NULL pointer checks to ensure stability by preventing operations > on an invalid CRTC state. > > Fixes: d208261e9f7c ("drm/mediatek: Add wait_event_timeout when disabling plane") > Signed-off-by: Jason-JH Lin Reviewed-by: AngeloGioacchino Del Regno