From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>,
"Rob Herring (Arm)" <robh@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: 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: Wed, 18 Dec 2024 15:13:13 +0106 [thread overview]
Message-ID: <84wmfxm6em.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <Z2K_u6jK5aLDqaam@pathway.suse.cz>
On 2024-12-18, Petr Mladek <pmladek@suse.com> wrote:
> My concern is taking a lock when processing a printf format, see
> below for more details.
Your concern is valid! printk() uses vsnprintf() to format records for
the kernel log. printk() may be called from contexts where locking is
forbidden (such as NMI). If vsnprintf() can take a lock, then either:
vsnprintf() must be made to be lockless
or
printk() must take another approach to string formatting
or
we accept that printk() can deadlock for certain format types in certain
contexts.
John Ogness
next prev parent reply other threads:[~2024-12-18 14:07 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 [this message]
2024-12-19 15:05 ` Petr Mladek
2024-12-19 19:11 ` John Ogness
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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