seize: don't detach from a task if a freezer cgroup is set

criu detaches from tasks in freezer_detach() in this case
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

ptrace.c

@@ -21,6 +21,7 @@
 #include "proc_parse.h"
 #include "crtools.h"
 #include "seccomp.h"
+#include "cr_options.h"
 
 int unseize_task(pid_t pid, int orig_st, int st)
 {
@@ -49,6 +50,9 @@ int unseize_task(pid_t pid, int orig_st, int st)
 	} else
 		pr_err("Unknown final state %d\n", st);
 
+	if (opts.freeze_cgroup)
+		return 0;
+
 	if (ptrace(PTRACE_DETACH, pid, NULL, NULL)) {
 		pr_perror("Unable to detach from %d", pid);
 		return -1;