kernel/fork.c:copy_process(): unify CLONE_THREAD-or-thread_group_leader code

Cleanup and preparation for the next changes.

Move the "if (clone_flags & CLONE_THREAD)" code down under "if
(likely(p->pid))" and turn it into into the "else" branch.  This makes the
process/thread initialization more symmetrical and removes one check.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Sergey Dyasly <dserrg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/fork.c

@@ -1446,14 +1446,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 		goto bad_fork_free_pid;
 	}
 
-	if (clone_flags & CLONE_THREAD) {
-		current->signal->nr_threads++;
-		atomic_inc(&current->signal->live);
-		atomic_inc(&current->signal->sigcnt);
-		p->group_leader = current->group_leader;
-		list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
-	}
-
 	if (likely(p->pid)) {
 		ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
 
@@ -1470,6 +1462,13 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 			list_add_tail(&p->sibling, &p->real_parent->children);
 			list_add_tail_rcu(&p->tasks, &init_task.tasks);
 			__this_cpu_inc(process_counts);
+		} else {
+			current->signal->nr_threads++;
+			atomic_inc(&current->signal->live);
+			atomic_inc(&current->signal->sigcnt);
+			p->group_leader = current->group_leader;
+			list_add_tail_rcu(&p->thread_group,
+					  &p->group_leader->thread_group);
 		}
 		attach_pid(p, PIDTYPE_PID, pid);
 		nr_threads++;