linux-kernel - Re: [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3cafe4fd-8a0b-2633-44a3-2995abd6c38c@arm.com>
Date:   Thu, 28 Apr 2022 09:11:10 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        akpm@...ux-foundation.org, bhe@...hat.com, pmladek@...e.com,
        kexec@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com, coresight@...ts.linaro.org,
        linuxppc-dev@...ts.ozlabs.org, linux-alpha@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-edac@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org,
        netdev@...r.kernel.org, openipmi-developer@...ts.sourceforge.net,
        rcu@...r.kernel.org, sparclinux@...r.kernel.org,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        kernel-dev@...lia.com, kernel@...ccoli.net, halves@...onical.com,
        fabiomirmar@...il.com, alejandro.j.jimenez@...cle.com,
        andriy.shevchenko@...ux.intel.com, arnd@...db.de, bp@...en8.de,
        corbet@....net, d.hatayama@...fujitsu.com,
        dave.hansen@...ux.intel.com, dyoung@...hat.com,
        feng.tang@...el.com, gregkh@...uxfoundation.org,
        mikelley@...rosoft.com, hidehiro.kawai.ez@...achi.com,
        jgross@...e.com, john.ogness@...utronix.de, keescook@...omium.org,
        luto@...nel.org, mhiramat@...nel.org, mingo@...hat.com,
        paulmck@...nel.org, peterz@...radead.org, rostedt@...dmis.org,
        senozhatsky@...omium.org, stern@...land.harvard.edu,
        tglx@...utronix.de, vgoyal@...hat.com, vkuznets@...hat.com,
        will@...nel.org, Leo Yan <leo.yan@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mike Leach <mike.leach@...aro.org>
Subject: Re: [PATCH 09/30] coresight: cpu-debug: Replace mutex with
 mutex_trylock on panic notifier

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 <leo.yan@...aro.org>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Mike Leach <mike.leach@...aro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@....com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.com>

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 <suzuki.poulose@....com>