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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 C9E88C433FE for ; Thu, 28 Apr 2022 08:46:06 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Kpq3107VBz3bxM for ; Thu, 28 Apr 2022 18:46:05 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=suzuki.poulose@arm.com; receiver=) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4KppHc2qB9z2xrS for ; Thu, 28 Apr 2022 18:11:54 +1000 (AEST) 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 0B87FED1; Thu, 28 Apr 2022 01:11:21 -0700 (PDT) Received: from [10.57.12.231] (unknown [10.57.12.231]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0E93F3F774; Thu, 28 Apr 2022 01:11:11 -0700 (PDT) Message-ID: <3cafe4fd-8a0b-2633-44a3-2995abd6c38c@arm.com> Date: Thu, 28 Apr 2022 09:11:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex_trylock on panic notifier To: "Guilherme G. Piccoli" , akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-10-gpiccoli@igalia.com> From: Suzuki K Poulose In-Reply-To: <20220427224924.592546-10-gpiccoli@igalia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Thu, 28 Apr 2022 18:45:42 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-hyperv@vger.kernel.org, halves@canonical.com, gregkh@linuxfoundation.org, peterz@infradead.org, alejandro.j.jimenez@oracle.com, linux-remoteproc@vger.kernel.org, feng.tang@intel.com, linux-mips@vger.kernel.org, hidehiro.kawai.ez@hitachi.com, sparclinux@vger.kernel.org, will@kernel.org, tglx@linutronix.de, linux-leds@vger.kernel.org, linux-s390@vger.kernel.org, mikelley@microsoft.com, john.ogness@linutronix.de, corbet@lwn.net, paulmck@kernel.org, fabiomirmar@gmail.com, x86@kernel.org, mingo@redhat.com, bcm-kernel-feedback-list@broadcom.com, xen-devel@lists.xenproject.org, dyoung@redhat.com, vgoyal@redhat.com, Mike Leach , linux-xtensa@linux-xtensa.org, dave.hansen@linux.intel.com, keescook@chromium.org, arnd@arndb.de, linux-pm@vger.kernel.org, coresight@lists.linaro.org, Leo Yan , linux-um@lists.infradead.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, luto@kernel.org, linux-tegra@vger.kernel.org, openipmi-developer@lists.sourceforge.net, andriy.shevchenko@linux.intel.com, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, jgross@suse.com, Mathieu Poirier , linux-parisc@vger.kernel.org, netdev@vger.kernel.org, kernel@gpiccoli.net, linux-kernel@vger.kernel.org, stern@rowland.harvard.edu, senozhatsky@chromium.org, d.hatayama@jp.fujitsu.com, mhiramat@kernel.org, kernel-dev@igalia.com, linux-alpha@vger.kernel.org, vkuznets@redhat.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Guilherme, On 27/04/2022 23:49, Guilherme G. Piccoli wrote: > The panic notifier infrastructure executes registered callbacks when > a panic event happens - such callbacks are executed in atomic context, > with interrupts and preemption disabled in the running CPU and all other > CPUs disabled. That said, mutexes in such context are not a good idea. > > This patch replaces a regular mutex with a mutex_trylock safer approach; > given the nature of the mutex used in the driver, it should be pretty > uncommon being unable to acquire such mutex in the panic path, hence > no functional change should be observed (and if it is, that would be > likely a deadlock with the regular mutex). > > Fixes: 2227b7c74634 ("coresight: add support for CPU debug module") > Cc: Leo Yan > Cc: Mathieu Poirier > Cc: Mike Leach > Cc: Suzuki K Poulose > Signed-off-by: Guilherme G. Piccoli How would you like to proceed with queuing this ? I am happy either way. In case you plan to push this as part of this series (I don't see any potential conflicts) : Reviewed-by: Suzuki K Poulose