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From: John Ogness <john.ogness@linutronix.de>
To: Daniel Bristot de Oliveira <bristot@kernel.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Steven Rostedt <rostedt@goodmis.org>
Cc: Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marco Elver <elver@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Gabriele Paoloni <gpaoloni@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Clark Williams <williams@redhat.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-trace-devel@vger.kernel.org
Subject: Re: [RFC V2 12/21] rv/reactor: Add the printk reactor
Date: Tue, 15 Feb 2022 11:09:55 +0106	[thread overview]
Message-ID: <87v8xg30qc.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <c1657d1c-0d2b-4aa3-c1ed-2ae6fdfcda86@kernel.org>

On 2022-02-14, Daniel Bristot de Oliveira <bristot@kernel.org> wrote:
> On 2/14/22 18:25, Shuah Khan wrote:
>> On 2/14/22 3:45 AM, Daniel Bristot de Oliveira wrote:
>>> Note: do not use this reactor with rq_lock taken, it will lock the
>>> system until printk can handle that.
>> 
>> Please give more details on "lock the system" and how locking
>> would impact users and system operation
>
> It is a deadlock on the rq_lock. Hopefully the new printk
> implementation handles that better.

I suggest using printk_deferred() for this reactor for now. With
printk_deferred() the message and timestamp are immediately and
locklessly stored in the buffer, and the printing is performed in a
separate context. printk_deferred() is safe for all contexts.

John

  parent reply	other threads:[~2022-02-15 10:04 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-14 10:44 [RFC V2 00/21] The Runtime Verification (RV) interface Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 01/21] rv: Add " Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 02/21] rv: Add runtime reactors interface Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 03/21] rv/include: Add helper functions for deterministic automata Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 04/21] rv/include: Add deterministic automata monitor definition via C macros Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 05/21] rv/include: Add tracing helper functions Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 06/21] tools/rv: Add dot2c Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 07/21] tools/rv: Add dot2k Daniel Bristot de Oliveira
2022-02-14 10:44 ` [RFC V2 08/21] rv/monitor: Add the wip monitor skeleton created by dot2k Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 09/21] rv/monitor: wip instrumentation and Makefile/Kconfig entries Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 10/21] rv/monitor: Add the wwnr monitor skeleton created by dot2k Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 11/21] rv/monitor: wwnr instrumentation and Makefile/Kconfig entries Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 12/21] rv/reactor: Add the printk reactor Daniel Bristot de Oliveira
2022-02-14 17:25   ` Shuah Khan
     [not found]     ` <c1657d1c-0d2b-4aa3-c1ed-2ae6fdfcda86@kernel.org>
2022-02-15 10:03       ` John Ogness [this message]
2022-02-15 12:43         ` Daniel Bristot de Oliveira
2022-02-15 13:33           ` John Ogness
2022-02-15 17:21             ` Daniel Bristot de Oliveira
2022-02-15 19:33               ` John Ogness
2022-02-16  8:58                 ` Daniel Bristot de Oliveira
2022-02-16 10:51                   ` John Ogness
2022-02-16 13:19                     ` Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 13/21] rv/reactor: Add the panic reactor Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 14/21] Documentation/rv: Add a basic documentation Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 15/21] Documentation/rv: Add deterministic automata monitor synthesis documentation Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 16/21] Documentation/rv: Add deterministic automata instrumentation documentation Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 17/21] watchdog/dev: Add tracepoints Daniel Bristot de Oliveira
2022-02-14 14:57   ` Guenter Roeck
2022-02-14 15:39     ` Daniel Bristot de Oliveira
2022-02-16 16:01   ` Peter.Enderborg
2022-02-17 16:27     ` Daniel Bristot de Oliveira
2022-02-17 17:27       ` Guenter Roeck
2022-02-17 17:49         ` Gabriele Paoloni
2022-02-17 17:56           ` Daniel Bristot de Oliveira
2022-02-17 18:17           ` Guenter Roeck
2022-02-17 18:32             ` Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 18/21] rv/monitor: Add safe watchdog monitor Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 19/21] rv/monitor: Add safe watchdog nowayout monitor Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 20/21] rv/safety_app: Add an safety_app sample Daniel Bristot de Oliveira
2022-02-14 10:45 ` [RFC V2 21/21] Documentation/rv: Add watchdog-monitor documentation Daniel Bristot de Oliveira

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