tty: Sanitize slavery and ctl tty setups

We need to do two non-trivial things with ttys -- interconnect
slaves to masters (or to each other) and setup ctl-tty restoring
task.

Now this is done in subsequently depending on each other steps:

1. collect ttys
2. interconnect slaves and mark ctl-tty tasks
3. collect fake fds for tty-ctl tasks
4. setup orphaned slaves

We can relax this logic in two ways:

1. don't split marking ctl-tty tasks and then creating fds for them
   do it in one step at the end
2. don't interconnect slaves with masters and orphaned slaves in
   two steps -- do it in one place after fds are collected
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -139,10 +139,6 @@ static int prepare_shared(void)
 		ret = prepare_fd_pid(pi->pid.virt, pi->rst);
 		if (ret < 0)
 			break;
-
-		ret = prepare_ctl_tty(pi->pid.virt, pi->rst, pi->ctl_tty_id);
-		if (ret < 0)
-			break;
 	}
 
 	if (ret < 0)
@@ -150,9 +146,7 @@ static int prepare_shared(void)
 
 	mark_pipe_master();
 
-	ret = tty_setup_orphan_slavery(&opts);
-	if (ret)
-		goto err;
+	tty_setup_slavery();
 
 	ret = resolve_unix_peers();
 	if (ret)

include/pstree.h

@@ -11,7 +11,6 @@ struct pstree_item {
 	pid_t			pgid;
 	pid_t			sid;
 	pid_t			born_sid;
-	u32			ctl_tty_id;
 	int			state;		/* TASK_XXX constants */
 	int			nr_threads;	/* number of threads */
 	struct pid		*threads;	/* array of threads */

include/tty.h

@@ -17,6 +17,6 @@ extern int dump_tty(struct fd_parms *p, int lfd, const struct cr_fdset *set);
 extern int collect_tty(void);
 extern int tty_is_master(struct fdinfo_list_entry *le);
 extern int prepare_shared_tty(void);
-extern int tty_setup_orphan_slavery(const struct cr_options *opts);
+extern void tty_setup_slavery(void);
 
 #endif /* CR_TTY_H__ */

tty.c

@@ -638,18 +638,15 @@ static int tty_find_restoring_task(struct tty_info *info)
 
 	pr_info("Set a control terminal to %d\n", info->tie->sid);
 
-	for_each_pstree_item(item) {
-		if (item->sid == info->tie->sid) {
-			item->ctl_tty_id = info->tfe->id;
-			return 0;
-		}
-	}
+	for_each_pstree_item(item)
+		if (item->sid == info->tie->sid)
+			return prepare_ctl_tty(item->pid.virt, item->rst, info->tfe->id);
 
 	pr_err("No task found with sid %d\n", info->tie->sid);
 	return -1;
 }
 
-int tty_setup_orphan_slavery(const struct cr_options *opts)
+static void tty_setup_orphan_slavery(void)
 {
 	struct tty_info *info, *peer, *m;
 
@@ -688,11 +685,9 @@ int tty_setup_orphan_slavery(const struct cr_options *opts)
 				 m->tfe->id);
 		}
 	}
-
-	return 0;
 }
 
-static int tty_setup_slavery(void)
+void tty_setup_slavery(void)
 {
 	struct tty_info *info, *peer, *m;
 
@@ -720,7 +715,7 @@ static int tty_setup_slavery(void)
 			tty_show_pty_info("    `- sibling", peer);
 	}
 
-	return 0;
+	tty_setup_orphan_slavery();
 }
 
 static int verify_termios(u32 id, TermiosEntry *e)
@@ -851,9 +846,6 @@ int collect_tty(void)
 	ret = collect_image(CR_FD_TTY, PB_TTY,
 			    sizeof(struct tty_info),
 			    collect_one_tty);
-	if (!ret)
-		ret = tty_setup_slavery();
-
 	return ret;
 }