multipathd deadlocks during restart

During restart multipathd might deadlock as the uevent handler
is missing a cleanup handler. Thus the thread might be terminated
while it still holds the vector lock.

Signed-off-by: Hannes Reinecke <hare@suse.de>

diff --git a/multipathd/main.c b/multipathd/main.c
index 6c5e243..3a6e88f 100644 (file)
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -895,13 +895,11 @@ exit_daemon (int status)
        if (status != 0)
                fprintf(stderr, "bad exit status. see daemon.log\n");
 
-       condlog(3, "unlink pidfile");
-       unlink(DEFAULT_PIDFILE);
-
-       pthread_mutex_lock(&exit_mutex);
-       pthread_cond_signal(&exit_cond);
-       pthread_mutex_unlock(&exit_mutex);
-
+       if (running_state != DAEMON_SHUTDOWN) {
+               pthread_mutex_lock(&exit_mutex);
+               pthread_cond_signal(&exit_cond);
+               pthread_mutex_unlock(&exit_mutex);
+       }
        return status;
 }
 
@@ -1560,6 +1558,7 @@ child (void * param)
        struct vectors * vecs;
        struct multipath * mpp;
        int i;
+       sigset_t set;
        int rc, pid_rc;
 
        mlockall(MCL_CURRENT | MCL_FUTURE);
@@ -1672,11 +1671,17 @@ child (void * param)
 
        running_state = DAEMON_RUNNING;
        pthread_cond_wait(&exit_cond, &exit_mutex);
+       /* Need to block these to avoid deadlocking */
+       sigemptyset(&set);
+       sigaddset(&set, SIGTERM);
+       sigaddset(&set, SIGINT);
+       pthread_sigmask(SIG_BLOCK, &set, NULL);
 
        /*
         * exit path
         */
        running_state = DAEMON_SHUTDOWN;
+       pthread_sigmask(SIG_UNBLOCK, &set, NULL);
        block_signal(SIGHUP, NULL);
        lock(vecs->lock);
        if (conf->queue_without_daemon == QUE_NO_DAEMON_OFF)