From: Olivier Houchard <ohouchard@haproxy.com>
Date: Wed, 29 Jan 2025 15:51:40 +0000 (+0100)
Subject: MEDIUM: fd: Wait if locked in fd_grab_tgid() and fd_take_tgid().
X-Git-Tag: v3.2-dev7~64
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=52b97ff8dd131f8d5c876372552c34a8590e3823;p=thirdparty%2Fhaproxy.git

MEDIUM: fd: Wait if locked in fd_grab_tgid() and fd_take_tgid().

Wait while the tgid is locked in fd_grab_tgid() and fd_take_tgid().
As that lock is barely used, it should have no impact.
---

diff --git a/include/haproxy/fd.h b/include/haproxy/fd.h
index a83539e48..cf00d1efb 100644
--- a/include/haproxy/fd.h
+++ b/include/haproxy/fd.h
@@ -373,6 +373,10 @@ static inline uint fd_take_tgid(int fd)
 	uint old;
 
 	old = _HA_ATOMIC_FETCH_ADD(&fdtab[fd].refc_tgid, 0x10000) & 0xffff;
+	while (old & 0x8000) {
+                old = _HA_ATOMIC_LOAD(&fdtab[fd].refc_tgid) & 0xffff;
+                __ha_cpu_relax();
+	}
 	if (likely(old))
 		return old;
 	HA_ATOMIC_SUB(&fdtab[fd].refc_tgid, 0x10000);
@@ -398,6 +402,11 @@ static inline uint fd_grab_tgid(int fd, uint desired_tgid)
 	uint old;
 
 	old = _HA_ATOMIC_FETCH_ADD(&fdtab[fd].refc_tgid, 0x10000) & 0xffff;
+	/* If the tgid is locked, wait until it no longer is */
+	while (old & 0x8000) {
+		old = _HA_ATOMIC_LOAD(&fdtab[fd].refc_tgid) & 0xffff;
+		__ha_cpu_relax();
+	}
 	if (likely(old == desired_tgid))
 		return 1;
 	HA_ATOMIC_SUB(&fdtab[fd].refc_tgid, 0x10000);