cgroups: move check for valid monitor process up

Cc: cenxianlong <cenxianlong@huawei.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 0df8506954d0e8e9e51133745487ee4cdb18e7b6..68d158aa30b1134a77f867c95514ceb7781ddd17 100644 (file)
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -1082,6 +1082,12 @@ __cgfsng_ops static void cgfsng_monitor_destroy(struct cgroup_ops *ops,
                if (!h->monitor_full_path)
                        continue;
 
+               /* Monitor might have died before we entered the cgroup. */
+               if (handler->monitor_pid <= 0) {
+                       WARN("No valid monitor process found while destroying cgroups");
+                       goto try_recursive_destroy;
+               }
+
                if (conf && conf->cgroup_meta.dir)
                        pivot_path = must_make_path(h->mountpoint,
                                                    h->container_base_path,
@@ -1098,12 +1104,10 @@ __cgfsng_ops static void cgfsng_monitor_destroy(struct cgroup_ops *ops,
                        goto try_recursive_destroy;
                }
 
-               if (handler->monitor_pid != 0) {
-                       ret = lxc_write_openat(pivot_path, "cgroup.procs", pidstr, len);
-                       if (ret != 0) {
-                               SYSWARN("Failed to move monitor %s to \"%s\"", pidstr, pivot_path);
-                               continue;
-                       }
+               ret = lxc_write_openat(pivot_path, "cgroup.procs", pidstr, len);
+               if (ret != 0) {
+                       SYSWARN("Failed to move monitor %s to \"%s\"", pidstr, pivot_path);
+                       continue;
                }
 
 try_recursive_destroy: