BUG/MINOR: quic: upgrade rdlock to wrlock for ODCID removal
When a quic_conn is found in the DCID tree, it can be removed from the
first ODCID tree. However, this operation must absolutely be run under a
write-lock to avoid race condition. To avoid to use the lock too
frequently, node.leaf_p is checked. This value is set to NULL after
ebmb_delete.
diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 624cb35..500814f 100644
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -3863,6 +3863,8 @@
struct quic_conn *qc = NULL;
struct ebmb_node *node;
struct quic_connection_id *id;
+ /* set if the quic_conn is found in the second DCID tree */
+ int found_in_dcid = 0;
HA_RWLOCK_RDLOCK(QUIC_LOCK, &l->rx.cids_lock);
@@ -3892,14 +3894,21 @@
id = ebmb_entry(node, struct quic_connection_id, node);
qc = id->qc;
+ found_in_dcid = 1;
+
+ end:
+ HA_RWLOCK_RDUNLOCK(QUIC_LOCK, &l->rx.cids_lock);
/* If found in DCIDs tree, remove the quic_conn from the ODCIDs tree.
* If already done, this is a noop.
+ *
+ * node.leaf_p is first checked to avoid unnecessary locking.
*/
- ebmb_delete(&qc->odcid_node);
-
- end:
- HA_RWLOCK_RDUNLOCK(QUIC_LOCK, &l->rx.cids_lock);
+ if (found_in_dcid && qc->odcid_node.node.leaf_p) {
+ HA_RWLOCK_WRLOCK(QUIC_LOCK, &l->rx.cids_lock);
+ ebmb_delete(&qc->odcid_node);
+ HA_RWLOCK_WRUNLOCK(QUIC_LOCK, &l->rx.cids_lock);
+ }
return qc;
}