BUG/MEDIUM: thread: mask stopping_threads with threads_enabled when checking it
When soft-stopping, there's a comparison between stopping_threads and
threads_enabled to make sure all threads are stopped, but this is not
correct and is racy since the threads_enabled bit is removed when a
thread is stopped but not its stopping_threads bit. The consequence is
that depending on timing, when stopping, if the first stopping thread
is fast enough to remove its bit from threads_enabled, the other threads
will see that stopping_threads doesn't match threads_enabled anymore and
will wait forever. As such the mask must be applied to stopping_threads
during the test. This issue was introduced in recent commit ef422ced9
("MEDIUM: thread: make stopping_threads per-group and add stopping_tgroups"),
no backport is needed.
diff --git a/src/haproxy.c b/src/haproxy.c
index e8c209e..f86e3b5 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -2840,7 +2840,8 @@
(_HA_ATOMIC_LOAD(&stopping_tgroup_mask) & all_tgroups_mask) == all_tgroups_mask) {
/* check that all threads are aware of the stopping status */
for (i = 0; i < global.nbtgroups; i++)
- if (_HA_ATOMIC_LOAD(&ha_tgroup_ctx[i].stopping_threads) != ha_tgroup_info[i].threads_enabled)
+ if ((_HA_ATOMIC_LOAD(&ha_tgroup_ctx[i].stopping_threads) & ha_tgroup_info[i].threads_enabled) !=
+ ha_tgroup_info[i].threads_enabled)
break;
#ifdef USE_THREAD
if (i == global.nbtgroups) {