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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D2F57C44536 for ; Wed, 21 Jan 2026 16:03:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TGxi1IBvSvj30dcQyk0icAckGfgmaV2Be9CJDgxDFo4=; b=u7RAwEdRLIqhHC91SxuPJxribH od5gm2v7XtXInP0kIP0VLdIJydVwKxcbAgoXSckzmjxpKIpe4374tY3j4wzl7KTWsGrTJwxtjMOi2 XPA1NY7o5VZPBFmaPCe2P9xd5QChRLvzgcMlZMPMX+sfPN2pc5P9M9Kgpq1CUKmrIf7ZY36EHsgCO nz12AjVn/S4NGfoby3GK+PLbLoYNnWBoFZLDerO/s83FjPB6bsgabW/6/iNYNGW1Jebxz0wB5ywCd r8sCqyPV9ZT0nu5HPC1wrigAHWPihAQINHyddIs8t10Ani8RTtCb/1uZXTLdAEUd/vC8OdAx00zJj II9sWnMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1viafe-00000005lDs-2JaL; Wed, 21 Jan 2026 16:03:02 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1viafb-00000005lDM-2LBQ for linux-arm-kernel@lists.infradead.org; Wed, 21 Jan 2026 16:03:01 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 5695443721; Wed, 21 Jan 2026 16:02:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F623C4CEF1; Wed, 21 Jan 2026 16:02:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769011378; bh=F9bPyEYde8jlWbcHshXKq3vOhM722s15C6Irbdet8y4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=UEjgfzQ3Yy0qFP25NRRt1WZG1cmk7k0VEnQyB8xip8s2J6UnYdkTSBrR1Yq5U5+uE 0/AMp8dQ8UaAL5vlNQGvE9xgYcRJVF0kJWMhmWCsTdQNmZVK9sqPcE4qTgwq9H8WSj +edWOKkfUP1XsY2kX/WO0nFvUK1NoTGdG+c5J/t7AK6agi9xolmIkOLVY+xnrq6eyI cR34/ZA8hz0wwyIEkWqCXlqQVA7JQ6csR+zf/w4CwHgQ8FI+Drz8Fh26vbcjxjMiep BGokjRjztegbw7pmQzjoicX9UM4NLWmZ7j6cw72innV0l4eFnts4DACl/UfmFE2gFl I9owkn1KBx8fg== Message-ID: <35780b65-8c95-4d58-8d4a-2f451cf5377d@kernel.org> Date: Wed, 21 Jan 2026 17:02:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] iommu/arm-smmu-qcom: do not register driver in probe() To: Danilo Krummrich , gregkh@linuxfoundation.org, rafael@kernel.org, broonie@kernel.org, will@kernel.org, robin.murphy@arm.com, joro@8bytes.org, robin.clark@oss.qualcomm.com, hanguidong02@gmail.com, quic_c_gdjako@quicinc.com, dmitry.baryshkov@oss.qualcomm.com Cc: driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-arm-msm@vger.kernel.org References: <20260121141215.29658-1-dakr@kernel.org> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260121141215.29658-1-dakr@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260121_080259_626473_E80768F0 X-CRM114-Status: GOOD ( 14.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/21/26 3:12 PM, Danilo Krummrich wrote: > Commit 0b4eeee2876f ("iommu/arm-smmu-qcom: Register the TBU driver in > qcom_smmu_impl_init") intended to also probe the TBU driver when > CONFIG_ARM_SMMU_QCOM_DEBUG is disabled, but also moved the corresponding > platform_driver_register() call into qcom_smmu_impl_init() which is > called from arm_smmu_device_probe(). > > However, it neither makes sense to register drivers from probe() > callbacks of other drivers, nor does the driver core allow registering > drivers with a device lock already being held. > > The latter was revealed by commit dc23806a7c47 ("driver core: enforce > device_lock for driver_match_device()") leading to a deadlock condition > described in [1]. > > Additionally, it was noted by Robin that the current approach is > potentially racy with async probe [2]. > > Hence, fix this by registering the qcom_smmu_tbu_driver from > module_init(). Unfortunately, due to the vendoring of the driver, this > requires an indirection through arm-smmu-impl.c. > > Reported-by: Mark Brown > Closes: https://lore.kernel.org/lkml/7ae38e31-ef31-43ad-9106-7c76ea0e8596@sirena.org.uk/ > Link: https://lore.kernel.org/lkml/DFU7CEPUSG9A.1KKGVW4HIPMSH@kernel.org/ [1] > Link: https://lore.kernel.org/lkml/0c0d3707-9ea5-44f9-88a1-a65c62e3df8d@arm.com/ [2] > Fixes: dc23806a7c47 ("driver core: enforce device_lock for driver_match_device()") > Fixes: 0b4eeee2876f ("iommu/arm-smmu-qcom: Register the TBU driver in qcom_smmu_impl_init") > Signed-off-by: Danilo Krummrich > --- Acked-by: Konrad Dybcio Konrad