From: Valentine Krasnobaeva <vkrasnobaeva@haproxy.com>
Date: Tue, 18 Mar 2025 15:33:54 +0000 (+0100)
Subject: BUG/MINOR: limits: compute_ideal_maxconn: don't cap remain if fd_hard_limit=0
X-Git-Tag: v3.2-dev8~26
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=060f441199aa97d9735dd553bafd231ca615f723;p=thirdparty%2Fhaproxy.git

BUG/MINOR: limits: compute_ideal_maxconn: don't cap remain if fd_hard_limit=0

'global.fd_hard_limit' stays uninitialized, if haproxy is started with -m
(global.rlimit_memmax). 'remain' is the MAX between soft and hard process fd
limits. It will be always bigger than 'global.fd_hard_limit' (0) in this case.

So, if we reassign 'remain' to the 'global.fd_hard_limit' unconditionally,
calculated then 'maxconn' will be even negative and the DEFAULT_MAXCONN (100)
will be set as the 'ideal_maxconn'.

During the 'global.maxconn' calculations in set_global_maxconn(), if the
provided 'global.rlimit_memmax' is quite big, system will refuse to calculate
based on its 'global.maxconn' and we will do a fallback to the 'ideal_maxconn',
which is 100.

Same problem for the configs with SSL frontends and backends.

This fixes the issue #2899.

This should be backported to v3.1.0.
---

diff --git a/src/limits.c b/src/limits.c
index 83ddb37e4..e9ce8b8d7 100644
--- a/src/limits.c
+++ b/src/limits.c
@@ -152,8 +152,14 @@ static int compute_ideal_maxconn()
 	if (!is_any_limit_configured())
 		global.fd_hard_limit = DEFAULT_MAXFD;
 
-	if (remain > global.fd_hard_limit)
+	if (global.fd_hard_limit && (remain > global.fd_hard_limit)) {
+		/* cap remain only when global.fd_hard_limit > 0, i.e.: either
+		 * there were no any other limits set and it's defined by lines
+		 * above as DEFAULT_MAXFD (100), or fd_hard_limit is explicitly
+		 * provided in config.
+		 */
 		remain = global.fd_hard_limit;
+	}
 
 	/* subtract listeners and checks */
 	remain -= global.maxsock;