Rework locking on timeout_mutex. We now drop (and reaquire) the lock inside the while loops. This is the least line of code changes to stop a dead lock between the queue in push2worker (a blocking function) and the timeout_mutex. These two timeout list iterations should be rewritten with better locking rules, but for now this should fix the bug, without rewriting the entire function.

PR: 41712


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@567852 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 5 insertions, 0 deletions

diff --git a/server/mpm/experimental/event/event.c b/server/mpm/experimental/event/event.c
index febdd78b0b..abee41be8c 100644
--- a/server/mpm/experimental/event/event.c
+++ b/server/mpm/experimental/event/event.c
@@ -1076,6 +1076,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy)
             cs->state = CONN_STATE_LINGER;
 
             APR_RING_REMOVE(cs, timeout_list);
+            apr_thread_mutex_unlock(timeout_mutex);
 
             rc = push2worker(&cs->pfd, event_pollset);
 
@@ -1088,6 +1089,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy)
                  */
             }
             have_idle_worker = 0;
+            apr_thread_mutex_lock(timeout_mutex);
             cs = APR_RING_FIRST(&keepalive_timeout_head);
         }
 
@@ -1099,11 +1101,14 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy)
 
             cs->state = CONN_STATE_LINGER;
             APR_RING_REMOVE(cs, timeout_list);
+            apr_thread_mutex_unlock(timeout_mutex);
+
             rc = push2worker(&cs->pfd, event_pollset);
             if (rc != APR_SUCCESS) {
                 return NULL;
             }
             have_idle_worker = 0;
+            apr_thread_mutex_lock(timeout_mutex);
             cs = APR_RING_FIRST(&timeout_head);
         }