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Revert "MINOR: queue: use atomic-ops to update the queue's index"

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This reverts commit 1335eb9867.

The recent changes since 5304669e1 MEDIUM: queue: make
pendconn_process_next_strm() only return the pendconn opened a tiny race
condition between stream_free() and process_srv_queue(), as the pendconn
is accessed outside of the lock, possibly while it's being freed. A
different approach is required.
This commit is contained in:
Willy Tarreau 2021-06-24 07:22:12 +02:00
parent ddac4a1f35
commit a4a9bbadc6
1 changed files with 5 additions and 5 deletions
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10
src/queue.c
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@ -133,7 +133,7 @@ unsigned int srv_dynamic_maxconn(const struct server *s)
*/
static void __pendconn_unlink_srv(struct pendconn *p)
{
p->strm->logs.srv_queue_pos += _HA_ATOMIC_LOAD(&p->srv->queue.idx) - p->queue_idx;
p->strm->logs.srv_queue_pos += p->srv->queue.idx - p->queue_idx;
eb32_delete(&p->node);
}
@ -146,7 +146,7 @@ static void __pendconn_unlink_srv(struct pendconn *p)
*/
static void __pendconn_unlink_prx(struct pendconn *p)
{
p->strm->logs.prx_queue_pos += _HA_ATOMIC_LOAD(&p->px->queue.idx) - p->queue_idx;
p->strm->logs.prx_queue_pos += p->px->queue.idx - p->queue_idx;
eb32_delete(&p->node);
}
@ -313,16 +313,16 @@ static struct pendconn *pendconn_process_next_strm(struct server *srv, struct pr
use_pp:
/* Let's switch from the server pendconn to the proxy pendconn */
__pendconn_unlink_prx(pp);
_HA_ATOMIC_INC(&px->queue.idx);
_HA_ATOMIC_DEC(&px->queue.length);
_HA_ATOMIC_DEC(&px->totpend);
px->queue.idx++;
p = pp;
goto unlinked;
use_p:
__pendconn_unlink_srv(p);
_HA_ATOMIC_INC(&srv->queue.idx);
_HA_ATOMIC_DEC(&srv->queue.length);
_HA_ATOMIC_DEC(&px->totpend);
srv->queue.idx++;
unlinked:
p->strm_flags |= SF_ASSIGNED;
p->target = srv;
@ -422,7 +422,6 @@ struct pendconn *pendconn_add(struct stream *strm)
max_ptr = &px->be_counters.nbpend_max;
}
p->queue_idx = _HA_ATOMIC_LOAD(&q->idx) - 1; // for logging only
new_max = _HA_ATOMIC_ADD_FETCH(&q->length, 1);
old_max = _HA_ATOMIC_LOAD(max_ptr);
while (new_max > old_max) {
@ -432,6 +431,7 @@ struct pendconn *pendconn_add(struct stream *strm)
__ha_barrier_atomic_store();
HA_SPIN_LOCK(QUEUE_LOCK, &q->lock);
p->queue_idx = q->idx - 1; // for increment
eb32_insert(&q->head, &p->node);
HA_SPIN_UNLOCK(QUEUE_LOCK, &q->lock);