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OpenCloudOS-Kernel
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Merge branch 'rework/fast-next-seq' into for-linus

This commit is contained in:
Petr Mladek 2022-03-21 14:46:19 +01:00
parent 1ccd85f5ac f244b4dc53
commit 5eb17c1f45
2 changed files with 49 additions and 5 deletions
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52
kernel/printk/printk_ringbuffer.c
View File

@ -474,8 +474,10 @@ static enum desc_state desc_read(struct prb_desc_ring *desc_ring,
* state has been re-checked. A memcpy() for all of @desc
* cannot be used because of the atomic_t @state_var field.
*/
memcpy(&desc_out->text_blk_lpos, &desc->text_blk_lpos,
sizeof(desc_out->text_blk_lpos)); /* LMM(desc_read:C) */
if (desc_out) {
memcpy(&desc_out->text_blk_lpos, &desc->text_blk_lpos,
sizeof(desc_out->text_blk_lpos)); /* LMM(desc_read:C) */
}
if (seq_out)
*seq_out = info->seq; /* also part of desc_read:C */
if (caller_id_out)
@ -528,7 +530,8 @@ static enum desc_state desc_read(struct prb_desc_ring *desc_ring,
state_val = atomic_long_read(state_var); /* LMM(desc_read:E) */
d_state = get_desc_state(id, state_val);
out:
atomic_long_set(&desc_out->state_var, state_val);
if (desc_out)
atomic_long_set(&desc_out->state_var, state_val);
return d_state;
}
@ -1449,6 +1452,9 @@ static void desc_make_final(struct prb_desc_ring *desc_ring, unsigned long id)
atomic_long_cmpxchg_relaxed(&d->state_var, prev_state_val,
DESC_SV(id, desc_finalized)); /* LMM(desc_make_final:A) */
/* Best effort to remember the last finalized @id. */
atomic_long_set(&desc_ring->last_finalized_id, id);
}
/**
@ -1657,7 +1663,12 @@ void prb_commit(struct prb_reserved_entry *e)
*/
void prb_final_commit(struct prb_reserved_entry *e)
{
struct prb_desc_ring *desc_ring = &e->rb->desc_ring;
_prb_commit(e, desc_finalized);
/* Best effort to remember the last finalized @id. */
atomic_long_set(&desc_ring->last_finalized_id, e->id);
}
/*
@ -2005,9 +2016,39 @@ u64 prb_first_valid_seq(struct printk_ringbuffer *rb)
*/
u64 prb_next_seq(struct printk_ringbuffer *rb)
{
u64 seq = 0;
struct prb_desc_ring *desc_ring = &rb->desc_ring;
enum desc_state d_state;
unsigned long id;
u64 seq;
/* Search forward from the oldest descriptor. */
/* Check if the cached @id still points to a valid @seq. */
id = atomic_long_read(&desc_ring->last_finalized_id);
d_state = desc_read(desc_ring, id, NULL, &seq, NULL);
if (d_state == desc_finalized || d_state == desc_reusable) {
/*
* Begin searching after the last finalized record.
*
* On 0, the search must begin at 0 because of hack#2
* of the bootstrapping phase it is not known if a
* record at index 0 exists.
*/
if (seq != 0)
seq++;
} else {
/*
* The information about the last finalized sequence number
* has gone. It should happen only when there is a flood of
* new messages and the ringbuffer is rapidly recycled.
* Give up and start from the beginning.
*/
seq = 0;
}
/*
* The information about the last finalized @seq might be inaccurate.
* Search forward to find the current one.
*/
while (_prb_read_valid(rb, &seq, NULL, NULL))
seq++;
@ -2044,6 +2085,7 @@ void prb_init(struct printk_ringbuffer *rb,
rb->desc_ring.infos = infos;
atomic_long_set(&rb->desc_ring.head_id, DESC0_ID(descbits));
atomic_long_set(&rb->desc_ring.tail_id, DESC0_ID(descbits));
atomic_long_set(&rb->desc_ring.last_finalized_id, DESC0_ID(descbits));
rb->text_data_ring.size_bits = textbits;
rb->text_data_ring.data = text_buf;

2
kernel/printk/printk_ringbuffer.h
View File

@ -75,6 +75,7 @@ struct prb_desc_ring {
struct printk_info *infos;
atomic_long_t head_id;
atomic_long_t tail_id;
atomic_long_t last_finalized_id;
};
/*
@ -258,6 +259,7 @@ static struct printk_ringbuffer name = { \
.infos = &_##name##_infos[0], \
.head_id = ATOMIC_INIT(DESC0_ID(descbits)), \
.tail_id = ATOMIC_INIT(DESC0_ID(descbits)), \
.last_finalized_id = ATOMIC_INIT(DESC0_ID(descbits)), \
}, \
.text_data_ring = { \
.size_bits = (avgtextbits) + (descbits), \