From: Willy Tarreau <w@1wt.eu>
Date: Thu, 24 Jun 2021 05:26:57 +0000 (+0200)
Subject: Revert "MEDIUM: queue: refine the locking in process_srv_queue()"
X-Git-Tag: v2.5-dev1~34
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e76fc3253d8e1982c881e1ea79b03f69b7a0c4f3;p=thirdparty%2Fhaproxy.git

Revert "MEDIUM: queue: refine the locking in process_srv_queue()"

This reverts commit 1b648c857bb9e0fb857e86838bcca0c9ed01e2bd.

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.
---

diff --git a/src/queue.c b/src/queue.c
index c9134afb92..d8e73b2181 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -340,29 +340,27 @@ void process_srv_queue(struct server *s, int server_locked)
 	int done = 0;
 	int maxconn;
 
+	if (!server_locked)
+		HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
+	HA_RWLOCK_WRLOCK(PROXY_LOCK,  &p->lock);
 	maxconn = srv_dynamic_maxconn(s);
 	while (s->served < maxconn) {
 		struct pendconn *pc;
 
-		if (!server_locked)
-			HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
-		HA_RWLOCK_WRLOCK(PROXY_LOCK,  &p->lock);
-
 		pc = pendconn_process_next_strm(s, p);
-
-		HA_RWLOCK_WRUNLOCK(PROXY_LOCK,  &p->lock);
-		if (!server_locked)
-			HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
-
 		if (!pc)
 			break;
 
 		done++;
 
 		_HA_ATOMIC_INC(&s->served);
+
 		stream_add_srv_conn(pc->strm, s);
 		task_wakeup(pc->strm->task, TASK_WOKEN_RES);
 	}
+	HA_RWLOCK_WRUNLOCK(PROXY_LOCK,  &p->lock);
+	if (!server_locked)
+		HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
 
 	_HA_ATOMIC_ADD(&p->served, done);