From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>
Cc: "Rob Herring (Arm)" <robh@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Jonathan Corbet <corbet@lwn.net>,
Saravana Kannan <saravanak@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Zijun Hu <quic_zijuhu@quicinc.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org
Subject: Re: lock in vsprintf(): was: Re: [PATCH] of: Add printf '%pOFm' for generating modalias
Date: Thu, 19 Dec 2024 20:17:21 +0106 [thread overview]
Message-ID: <84o7171o9y.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <Z2Q2TcM6QPUIIyLC@pathway.suse.cz>
On 2024-12-19, Petr Mladek <pmladek@suse.com> wrote:
> I do not want to revert everything now just because of theoretical
> problems.
What would you revert? This has always been an issue for printk().
> Well, it would be nice to document the lock dependency in
> Documentation/core-api/printk-formats.rst
Yes. If any locking is involved at all, such specifiers should be
documented as not safe in NMI context or within printk_cpu_sync
blocks. Also, it should be checked if all such locks are
raw_spinlock_t. If any other lock type is used, it probably is already
generating a lockdep splat since printk() formats records with local
interrupts off.
Perhaps we should create a kunit that calls printk() for each of the
supported specifiers and see if any lockdep splats appear.
John
next prev parent reply other threads:[~2024-12-19 19:11 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-17 18:37 [PATCH] of: Add printf '%pOFm' for generating modalias Rob Herring (Arm)
2024-12-18 2:21 ` quic_zijuhu
2024-12-18 10:16 ` Rasmus Villemoes
2024-12-18 15:28 ` Rob Herring
2024-12-18 11:35 ` ssize_t: was: " Petr Mladek
2024-12-18 17:10 ` Rob Herring
2024-12-19 14:44 ` Petr Mladek
2024-12-18 12:27 ` lock in vsprintf(): " Petr Mladek
2024-12-18 14:07 ` John Ogness
2024-12-19 15:05 ` Petr Mladek
2024-12-19 19:11 ` John Ogness [this message]
2024-12-20 8:01 ` Petr Mladek
2024-12-30 20:26 ` Rob Herring
2025-01-02 13:06 ` Petr Mladek
2025-01-02 14:02 ` John Ogness
2024-12-18 16:29 ` Rob Herring
2024-12-18 16:31 ` Steven Rostedt
2024-12-23 19:58 ` Andy Shevchenko
2024-12-30 20:52 ` Rob Herring
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