printk: Wait for all reserved records with pr_flush()

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Currently pr_flush() will only wait for records that were
available to readers at the time of the call (using
prb_next_seq()). But there may be more records (non-finalized)
that have following finalized records. pr_flush() should wait
for these to print as well. Particularly because any trailing
finalized records may be the messages that the calling context
wants to ensure are printed.

Add a new ringbuffer function prb_next_reserve_seq() to return
the sequence number following the most recently reserved record.
This guarantees that pr_flush() will wait until all current
printk() messages (completed or in progress) have been printed.

Fixes: 3b604ca812 ("printk: add pr_flush()")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240207134103.1357162-10-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>

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John Ogness 2024-02-07 14:46:58 +01:06 • committed by Petr Mladek

parent 584528d621

commit ac7d7844c6

3 changed files with 107 additions and 1 deletions

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2

kernel/printk/printk.c

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105

kernel/printk/printk_ringbuffer.c

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1

kernel/printk/printk_ringbuffer.h

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