mirror_ubuntu-kernels/kernel/printk
Thomas Gleixner ecb5e1aa82 printk: nbcon: Implement emergency sections
In emergency situations (something has gone wrong but the
system continues to operate), usually important information
(such as a backtrace) is generated via printk(). This
information should be pushed out to the consoles ASAP.

Add per-CPU emergency nesting tracking because an emergency
can arise while in an emergency situation.

Add functions to mark the beginning and end of emergency
sections where the urgent messages are generated.

Perform direct console flushing at the emergency priority if
the current CPU is in an emergency state and it is safe to do
so.

Note that the emergency state is not system-wide. While one CPU
is in an emergency state, another CPU may attempt to print
console messages at normal priority.

Also note that printk() already attempts to flush consoles in
the caller context for normal priority. However, follow-up
changes will introduce printing kthreads, in which case the
normal priority printk() calls will offload to the kthreads.

Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240820063001.36405-32-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-08-21 15:03:04 +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: nbcon: Implement emergency sections 2024-08-21 15:03:04 +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: Implement emergency sections 2024-08-21 15:03:04 +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: Do not rely on proxy headers 2024-08-21 14:56:23 +02:00
printk_safe.c printk: Add is_printk_legacy_deferred() 2024-08-21 14:56:24 +02:00
printk.c printk: Add helper for flush type logic 2024-08-21 14:56:49 +02:00
sysctl.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00