linux-next/kernel/printk
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() 2023-02-03 10:42:02 +01:00
internal.h printk: Implement legacy printer kthread for PREEMPT_RT 2024-09-04 15:56:33 +02:00
Makefile Revert "printk: Save console options for add_preferred_console_match()" 2024-06-25 07:58:10 +02:00
nbcon.c printk: nbcon: Assign nice -20 for printing threads 2024-09-04 15:56:33 +02:00
printk_ringbuffer.c printk: ringbuffer: Skip non-finalized records in panic 2024-02-07 17:23:18 +01:00
printk_ringbuffer.h printk: nbcon: Init @nbcon_seq to highest possible 2024-09-04 15:56:32 +02:00
printk_safe.c printk: Implement legacy printer kthread for PREEMPT_RT 2024-09-04 15:56:33 +02:00
printk.c printk: Avoid false positive lockdep report for legacy printing 2024-09-04 15:56:33 +02:00
sysctl.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00