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Merge branch 'rework/prb-fixes' into for-linus

master
Petr Mladek 2026-04-20 13:42:01 +02:00
parent 3e9e952bb3 bf56987c11
commit add9d911be
2 changed files with 17 additions and 14 deletions
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27
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);
*
@ -1302,23 +1302,26 @@ static const char *get_data(struct prb_data_ring *data_ring,
return NULL;
}
/* Sanity check. Data-less blocks were handled earlier. */
if (WARN_ON_ONCE(!data_check_size(data_ring, *data_size) || !*data_size))
return NULL;
/* A valid data block will always be aligned to the ID size. */
if (WARN_ON_ONCE(blk_lpos->begin != ALIGN(blk_lpos->begin, sizeof(db->id))) ||
WARN_ON_ONCE(blk_lpos->next != ALIGN(blk_lpos->next, sizeof(db->id)))) {
return NULL;
}
/* A valid data block will always have at least an ID. */
if (WARN_ON_ONCE(*data_size < sizeof(db->id)))
/*
* A regular data block will always have an ID and at least
* 1 byte of data. Data-less blocks were handled earlier.
*/
if (WARN_ON_ONCE(*data_size <= sizeof(db->id)))
return NULL;
/* Subtract block ID space from size to reflect data size. */
*data_size -= sizeof(db->id);
/* Sanity check the max size of the regular data block. */
if (WARN_ON_ONCE(!data_check_size(data_ring, *data_size)))
return NULL;
return &db->data[0];
}
@ -1365,7 +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) */
@ -1770,9 +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) */
@ -2035,7 +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) */
}

4
kernel/printk/printk_ringbuffer.h
View File

@ -127,7 +127,7 @@ enum desc_state {
};
#define _DATA_SIZE(sz_bits) (1UL << (sz_bits))
#define _DESCS_COUNT(ct_bits) (1U << (ct_bits))
#define _DESCS_COUNT(ct_bits) (1UL << (ct_bits))
#define DESC_SV_BITS BITS_PER_LONG
#define DESC_FLAGS_SHIFT (DESC_SV_BITS - 2)
#define DESC_FLAGS_MASK (3UL << DESC_FLAGS_SHIFT)
@ -388,7 +388,7 @@ 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.
*/