mount-util: make umount_and_rmdir_and_freep() cleanup handler deal with NULL

src/shared/mount-util.h

@@ -93,8 +93,10 @@ int mode_to_inaccessible_node(const char *runtime_dir, mode_t mode, char **dest)
 /* Useful for usage with _cleanup_(), unmounts, removes a directory and frees the pointer */
 static inline char* umount_and_rmdir_and_free(char *p) {
         PROTECT_ERRNO;
-        (void) umount_recursive(p, 0);
-        (void) rmdir(p);
+        if (p) {
+                (void) umount_recursive(p, 0);
+                (void) rmdir(p);
+        }
         return mfree(p);
 }
 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, umount_and_rmdir_and_free);