From: Willy Tarreau <w@1wt.eu>
Date: Wed, 17 Feb 2021 15:15:23 +0000 (+0100)
Subject: OPTIM: lb-first: do not take the server lock on take_conn/drop_conn
X-Git-Tag: v2.3.7~49
X-Git-Url: http://git.haproxy.org/?a=commitdiff_plain;h=7a413401483468c07d32b67b388d37eb6768e289;p=haproxy-2.3.git

OPTIM: lb-first: do not take the server lock on take_conn/drop_conn

The operations are only an insert and a delete into the LB tree, which
doesn't require the server's lock at all as the lbprm lock is already
held. Let's drop it.

(cherry picked from commit 6b96e0e9d204bb7e30222964d641cc28a0e4d0c0)
Signed-off-by: Willy Tarreau <w@1wt.eu>
---

diff --git a/src/lb_fas.c b/src/lb_fas.c
index 3debfec..9f6dc24 100644
--- a/src/lb_fas.c
+++ b/src/lb_fas.c
@@ -36,7 +36,7 @@ static inline void fas_remove_from_tree(struct server *s)
 
 /* simply removes a server from a tree.
  *
- * The server's lock and the lbprm's lock must be held.
+ * The lbprm's lock must be held.
  */
 static inline void fas_dequeue_srv(struct server *s)
 {
@@ -49,7 +49,7 @@ static inline void fas_dequeue_srv(struct server *s)
  * reached. It is important to understand that the server weight is not used
  * here.
  *
- * The server's lock and the lbprm's lock must be held.
+ * The lbprm's lock must be held.
  */
 static inline void fas_queue_srv(struct server *s)
 {
@@ -66,18 +66,12 @@ static inline void fas_queue_srv(struct server *s)
  */
 static void fas_srv_reposition(struct server *s, int locked)
 {
-	if (!locked)
-		HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
-
 	HA_RWLOCK_WRLOCK(LBPRM_LOCK, &s->proxy->lbprm.lock);
 	if (s->lb_tree) {
 		fas_dequeue_srv(s);
 		fas_queue_srv(s);
 	}
 	HA_RWLOCK_WRUNLOCK(LBPRM_LOCK, &s->proxy->lbprm.lock);
-
-	if (!locked)
-		HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
 }
 
 /* This function updates the server trees according to server <srv>'s new