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 D5DFBCAC592 for ; Tue, 16 Sep 2025 16:42:20 +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=8XOuo23n5fwaFPItZ1inGNCeclcLdyo6m47GTm6ZkMM=; b=ElquY0B3szkALvmyysfLZi6bM6 ysA9aMcc7Ypf5n1b/7NljMFhYVT7Is59ORJQR5KVh0+PBiRznlCBfwJN24vBSQT0GVE3MkxkTADt3 /1X4FPQGb12baEbgkFVe+5cQItgxP4U5ZLZo8Q2H5xAPM2JYRmDWEFOGR3Zw27H0eJOyDO9J0Eitc /LVWEvsLNeP6oeHRI17kEn7DnG58Jnw/yiqqgyxhKwxGMFmeKT13dHOxY/+K0jx2E2PSPyWS9+2Dj TKXuMR/Y5nAL5jlYo7KxA8IGeZeNrJPbxiEt7Zkptw65BsLJUM1TY11b8seNzPQrHA3mLTZyxPJmk bBy/CyVw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uyYkw-00000008V5u-0eqS; Tue, 16 Sep 2025 16:42:14 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uyYkt-00000008V5X-0jG7 for linux-arm-kernel@lists.infradead.org; Tue, 16 Sep 2025 16:42:12 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 372A11063; Tue, 16 Sep 2025 09:42:02 -0700 (PDT) Received: from [10.57.4.241] (unknown [10.57.4.241]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CB5903F673; Tue, 16 Sep 2025 09:42:08 -0700 (PDT) Message-ID: <8f426702-4897-4177-aeae-4fe2b7155fae@arm.com> Date: Tue, 16 Sep 2025 17:42:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] coresight: Fix possible deadlock in coresight_panic_cb Content-Language: en-GB To: Leo Yan Cc: Sean Anderson , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, Yeoreum Yun , Mike Leach , Linu Cherian , linux-kernel@vger.kernel.org, Alexander Shishkin , James Clark References: <20250912151314.3761026-1-sean.anderson@linux.dev> <20250915095820.GH12516@e132581.arm.com> <3e618117-96bd-44f3-bede-7cadfe0264dd@linux.dev> <20250916160027.GK12516@e132581.arm.com> <6fbd24b2-3315-45e6-bff2-2c39e899e8f5@arm.com> <20250916163840.GL12516@e132581.arm.com> From: Suzuki K Poulose In-Reply-To: <20250916163840.GL12516@e132581.arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250916_094211_260090_79504421 X-CRM114-Status: GOOD ( 13.13 ) 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 16/09/2025 17:38, Leo Yan wrote: > On Tue, Sep 16, 2025 at 05:09:01PM +0100, Suzuki Kuruppassery Poulose wrote: > > [...] > >>> From ea78dd22cbdd97f709c5991d5bd3be97be6e137e Mon Sep 17 00:00:00 2001 >>> From: Sean Anderson >>> Date: Tue, 16 Sep 2025 16:03:58 +0100 >>> Subject: [PATCH] coresight: Fix possible deadlock in coresight_panic_cb() >>> >>> coresight_panic_cb() is called during a panic. It invokes >>> bus_for_each_dev(), which then calls bus_to_subsys() and takes the >>> 'bus_kset->list_lock'. If a panic occurs after the lock has been >>> acquired, it can lead to a deadlock. >>> >>> Instead of using a common panic notifier to iterate the bus, this commit >>> directly registers the TMC device's panic notifier. This avoids bus >>> iteration and effectively eliminates the race condition that could cause >>> the deadlock. >> >> Well, if you are going that far, why not register the notifier from >> coresight-core ? > > I have thought this but gave up. > > When register a panic's notifier, it does not provide an argument for > passing a private data. So the code below uses container_of() to convert > notifier block pointer to the TMC driver data, as a result, the code is > specific to TMC driver. notifier_block in csdev ?