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 9B4E9C433FE for ; Thu, 28 Apr 2022 08:11:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343833AbiD1IOy (ORCPT ); Thu, 28 Apr 2022 04:14:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244874AbiD1IOg (ORCPT ); Thu, 28 Apr 2022 04:14:36 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 364F776282; Thu, 28 Apr 2022 01:11:21 -0700 (PDT) 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 0C4C213D5; 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 Cc: linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, coresight@lists.linaro.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-pm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, netdev@vger.kernel.org, openipmi-developer@lists.sourceforge.net, rcu@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, Leo Yan , Mathieu Poirier , Mike Leach 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 Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org 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 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki K Poulose Date: Thu, 28 Apr 2022 09:11:10 +0100 Subject: [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex_trylock on panic notifier In-Reply-To: <20220427224924.592546-10-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-10-gpiccoli@igalia.com> Message-ID: <3cafe4fd-8a0b-2633-44a3-2995abd6c38c@arm.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <3cafe4fd-8a0b-2633-44a3-2995abd6c38c@arm.com> Date: Thu, 28 Apr 2022 09:11:10 +0100 MIME-Version: 1.0 Subject: Re: [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex_trylock on panic notifier 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> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: "Guilherme G. Piccoli" , akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, coresight@lists.linaro.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-pm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, netdev@vger.kernel.org, openipmi-developer@lists.sourceforge.net, rcu@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, Leo Yan , Mathieu Poirier , Mike Leach 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 _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki K Poulose Subject: Re: [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex_trylock on panic notifier Date: Thu, 28 Apr 2022 09:11:10 +0100 Message-ID: <3cafe4fd-8a0b-2633-44a3-2995abd6c38c@arm.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-10-gpiccoli@igalia.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20220427224924.592546-10-gpiccoli-wEGTBA9jqPzQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: "Guilherme G. Piccoli" , akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, pmladek-IBi9RG/b67k@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, coresight-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-alpha-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-edac-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-hyperv-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-leds-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mips-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-parisc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-remoteproc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-um-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-xtensa-PjhNF2WwrV/0Sa2dR60CXw@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, openipmi-developer-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, rcu-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sparclinux-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, xen-devel-GuqFBffKawtpuQazS67q72D2FQJk+8+b@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, kernel-dev-wEGTBA9jqPzQT0dZR+AlfA@public.gmane.org, kernel-WeLdAqEWwDvk1uMJSBkQmQ@public.gmane.org, halves-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org, fabiomirmar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, alejandro.j.jimenez@ora 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