printk: Introduce FORCE_CON flag

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Introduce FORCE_CON flag to printk. The new flag will make it possible to
create a context where printk messages will never be suppressed.

This mechanism will be used in the next patch to create a force_con
context on sysrq handling, removing an existing workaround on the
loglevel global variable. The workaround existed to make sure that sysrq
header messages were sent to all consoles, but this doesn't work with
deferred messages because the loglevel might be restored to its original
value before a console flushes the messages.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20241105-printk-loud-con-v2-1-bd3ecdf7b0e4@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>

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This commit is contained in:

Marcos Paulo de Souza 2024-11-05 16:45:08 -03:00 • committed by Petr Mladek

parent c903327d32

commit ed76c07c68

4 changed files with 40 additions and 5 deletions

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3

include/linux/printk.h

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3

kernel/printk/internal.h

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21

kernel/printk/printk.c

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18

kernel/printk/printk_safe.c

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