From: Olivier Houchard <ohouchard@haproxy.com>
Date: Fri, 14 Aug 2026 14:33:10 +0000 (+0200)
Subject: BUG/MEDIUM: tasks: don't type-pun state and tid in builds without threads
X-Git-Tag: v3.5-dev5~33
X-Git-Url: https://git.kaiwu.me/?a=commitdiff_plain;h=c5f41118c01db4babcf6919f5eae4ce308adcfef;p=haproxy.git

BUG/MEDIUM: tasks: don't type-pun state and tid in builds without threads

__task_set_state_and_tid() updates t->state and t->tid at once through
an uint64_t cast, which violates strict aliasing. With threads the
__atomic builtins keep the compiler conservative, but without them the
accesses are plain, and gcc -O2 legitimately keeps using a stale
t->state: the CAS always fails and _task_wakeup() spins forever on the
first request until the watchdog kills the process.

Without threads there is no concurrency to protect against, so just
compare and assign the two fields directly.
---

diff --git a/src/haproxy.c b/src/haproxy.c
index 801bc6dfe..373429007 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -3946,18 +3946,6 @@ int main(int argc, char **argv)
 		}
 	}
 
-	/* When FD tables are not shared between thread groups, the poller
-	 * pipes of all threads must be created before any group unshares its
-	 * FD table, so that they are inherited into every group's table and
-	 * cross-group wake_thread() keeps working. This must be done for all
-	 * builds, including those without threads, since each thread will pick
-	 * its own pair from there.
-	 */
-	if (!fd_precreate_poller_pipes()) {
-		ha_alert("Failed to create the poller pipes.\n");
-		exit(1);
-	}
-
 	/* start threads 2 and above */
 	setup_extra_threads(&run_thread_poll_loop);
 
diff --git a/src/thread.c b/src/thread.c
index 3a6efe482..557af60fb 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -278,6 +278,16 @@ void setup_extra_threads(void *(*handler)(void *))
 	/* the startup thread will be thread 1 */
 	ha_pthread[0] = pthread_self();
 
+	/* When FD tables are not shared between thread groups, the poller
+	 * pipes of all threads must be created before any group unshares its
+	 * FD table, so that they are inherited into every group's table and
+	 * cross-group wake_thread() keeps working.
+	 */
+	if (!fd_precreate_poller_pipes()) {
+		ha_alert("Failed to create the poller pipes.\n");
+		exit(1);
+	}
+
 	/* Create one initial thread for each extra thread group. These will
 	 * each be responsible for creating their own extra threads. The first
 	 * group's initial thread is the current thread.