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printk: ringbuffer: fix errors in comments

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The printk ringbuffer implementation is described in the comment as
using three ringbuffers, but the current implementation uses two (desc
and data). Update the comment so it matches the code.

Fix few more known issues in the comments.

Signed-off-by: Loïc Grégoire <loicgre@gmail.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20260328021855.53956-1-loicgre@gmail.com
[pmladek@suse.com: Fixed few more issues in the comments by John Ogness.]
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Loïc Grégoire 2026-03-27 22:18:54 -04:00 committed by Petr Mladek
parent 407f666db2
commit bf56987c11
2 changed files with 7 additions and 7 deletions
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12
kernel/printk/printk_ringbuffer.c
View File

@ -14,7 +14,7 @@
*
* Data Structure
* --------------
* The printk_ringbuffer is made up of 3 internal ringbuffers:
* The printk_ringbuffer is made up of 2 internal ringbuffers:
*
* desc_ring
* A ring of descriptors and their meta data (such as sequence number,
@ -224,7 +224,7 @@
*
* prb_rec_init_rd(&r, &info, &text_buf[0], sizeof(text_buf));
*
* prb_for_each_record(0, &test_rb, &seq, &r) {
* prb_for_each_record(0, &test_rb, seq, &r) {
* if (info.seq != seq)
* pr_warn("lost %llu records\n", info.seq - seq);
*
@ -1368,7 +1368,7 @@ static struct prb_desc *desc_reopen_last(struct prb_desc_ring *desc_ring,
*
* WMB from _prb_commit:A to _prb_commit:B
* matching
* MB If desc_reopen_last:A to prb_reserve_in_last:A
* MB from desc_reopen_last:A to prb_reserve_in_last:A
*/
if (!atomic_long_try_cmpxchg(&d->state_var, &prev_state_val,
DESC_SV(id, desc_reserved))) { /* LMM(desc_reopen_last:A) */
@ -1773,9 +1773,9 @@ static void _prb_commit(struct prb_reserved_entry *e, unsigned long state_val)
*
* Relies on:
*
* MB _prb_commit:B to prb_commit:A
* MB from _prb_commit:B to prb_commit:A
* matching
* MB desc_reserve:D to desc_make_final:A
* MB from desc_reserve:D to desc_make_final:A
*/
if (!atomic_long_try_cmpxchg(&d->state_var, &prev_state_val,
DESC_SV(e->id, state_val))) { /* LMM(_prb_commit:B) */
@ -2038,7 +2038,7 @@ u64 prb_first_seq(struct printk_ringbuffer *rb)
*
* MB from desc_push_tail:B to desc_reserve:F
* matching
* RMB prb_first_seq:B to prb_first_seq:A
* RMB from prb_first_seq:B to prb_first_seq:A
*/
smp_rmb(); /* LMM(prb_first_seq:C) */
}

2
kernel/printk/printk_ringbuffer.h
View File

@ -383,7 +383,7 @@ for ((s) = from; prb_read_valid(rb, s, r); (s) = (r)->info->seq + 1)
*
* This is a macro for conveniently iterating over a ringbuffer.
* Note that @s may not be the sequence number of the record on each
* iteration. For the sequence number, @r->info->seq should be checked.
* iteration. For the sequence number, @i->seq should be checked.
*
* Context: Any context.
*/