linux/kernel/printk
Thomas Gleixner 4b08d9e24f printk: nbcon: Add ownership state functions
Provide functions that are related to the safe handover mechanism
and allow console drivers to dynamically specify unsafe regions:

 - nbcon_context_can_proceed()

   Invoked by a console owner to check whether a handover request
   is pending or whether the console has been taken over by another
   context. If a handover request is pending, this function will
   also perform the handover, thus cancelling its own ownership.

 - nbcon_context_enter_unsafe()/nbcon_context_exit_unsafe()

   Invoked by a console owner to denote that the driver is about
   to enter or leave a critical region where a take over is unsafe.
   The exit variant is the point where the current owner releases
   the lock for a higher priority context which asked for the
   friendly handover.

   The unsafe state is stored in the console state and allows a
   new context to make informed decisions whether to attempt a
   takeover of such a console. The unsafe state is also available
   to the driver so that it can make informed decisions about the
   required actions and possibly take a special emergency path.

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>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230916192007.608398-6-john.ogness@linutronix.de
2023-09-18 17:03:45 +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: Fix preferred console selection with multiple matches 2020-02-18 09:34:42 +01:00
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: Add buffer management 2023-09-18 17:03:45 +02:00
Makefile printk: Add non-BKL (nbcon) console basic infrastructure 2023-09-18 17:03:45 +02:00
nbcon.c printk: nbcon: Add ownership state functions 2023-09-18 17:03:45 +02:00
printk_ringbuffer.c printk: ringbuffer: Fix truncating buffer size min_t cast 2023-08-14 13:05:22 +02:00
printk_ringbuffer.h printk: ringbuffer: Improve prb_next_seq() performance 2022-01-26 16:00:32 +01:00
printk_safe.c printk: Consolidate console deferred printing 2023-07-20 13:06:22 +02:00
printk.c printk: nbcon: Add buffer management 2023-09-18 17:03:45 +02:00
sysctl.c printk: Fix incorrect __user type in proc_dointvec_minmax_sysadmin() 2022-02-03 11:27:38 -08:00