Sebastian Andrzej Siewior dc18c5b130 timekeeping: Add a lockdep override in tick_freeze()
[ Upstream commit 92e250c624ea37fde64bfd624fd2556f0d846f18 ]

tick_freeze() acquires a raw spinlock (tick_freeze_lock). Later in the
callchain (timekeeping_suspend() -> mc146818_avoid_UIP()) the RTC driver
acquires a spinlock which becomes a sleeping lock on PREEMPT_RT.  Lockdep
complains about this lock nesting.

Add a lockdep override for this special case and a comment explaining
why it is okay.

Reported-by: Borislav Petkov <bp@alien8.de>
Reported-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250404133429.pnAzf-eF@linutronix.de
Closes: https://lore.kernel.org/all/20250330113202.GAZ-krsjAnurOlTcp-@fat_crate.local/
Closes: https://lore.kernel.org/all/CAP-bSRZ0CWyZZsMtx046YV8L28LhY0fson2g4EqcwRAVN1Jk+Q@mail.gmail.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-02 07:51:00 +02:00
2025-04-25 10:45:48 +02:00
2025-04-25 10:45:59 +02:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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