linux

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History

John Ogness daeed1595b printk: Avoid false positive lockdep report for legacy printing

Legacy console printing from printk() caller context may invoke
the console driver from atomic context. This leads to a lockdep
splat because the console driver will acquire a sleeping lock
and the caller may already hold a spinning lock. This is noticed
by lockdep on !PREEMPT_RT configurations because it will lead to
a problem on PREEMPT_RT.

However, on PREEMPT_RT the printing path from atomic context is
always avoided and the console driver is always invoked from a
dedicated thread. Thus the lockdep splat on !PREEMPT_RT is a
false positive.

For !PREEMPT_RT override the lock-context before invoking the
console driver to avoid the false positive.

Do not override the lock-context for PREEMPT_RT in order to
allow lockdep to catch any real locking context issues related
to the write callback usage.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-18-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>

2024-09-04 15:56:33 +02:00

braille.c

printk: Replace strncmp() with str_has_prefix()

2019-08-16 09:54:08 +02:00

braille.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

console_cmdline.h

printk: Add match_devname_and_update_preferred_console()

2024-07-04 15:41:44 +02:00

index.c

kernel/printk/index.c: fix memory leak with using debugfs_lookup()