[Devel] [PATCH rh7] vtty: Don't free console mapping until no clients left

[Cyrill Gorcunov]

Currently on container's stop we free vtty mapping in a force way
so that if there is active console hooked from the node it become
unusable since then. It was easier to work with when we've been
reworking virtual console code.

Now lets make console fully functional as it was in pcs6:
when opened it must survice container start/stop cycle
and checkpoint/restore as well.

For this sake we:

 - drop ve_hook code, it no longer needed
 - free console @map on final close of the last tty opened

https://jira.sw.ru/browse/PSBM-39463

Signed-off-by: Cyrill Gorcunov <gorcunov at virtuozzo.com>
CC: Vladimir Davydov <vdavydov at virtuozzo.com>
CC: Konstantin Khorenko <khorenko at virtuozzo.com>
CC: Igor Sukhih <igor at virtuozzo.com>
CC: Pavel Emelyanov <xemul at virtuozzo.com>
---
 drivers/tty/pty.c |   48 ++++++++++++++----------------------------------
 1 file changed, 14 insertions(+), 34 deletions(-)

Index: linux-pcs7.git/drivers/tty/pty.c
===================================================================
--- linux-pcs7.git.orig/drivers/tty/pty.c
+++ linux-pcs7.git/drivers/tty/pty.c
@@ -901,6 +901,13 @@ static void vtty_map_set(vtty_map_t *map
 	map->vttys[tty->index] = tty;
 }
 
+static void vtty_map_free(vtty_map_t *map)
+{
+	lockdep_assert_held(&tty_mutex);
+	idr_remove(&vtty_idr, map->veid);
+	kfree(map);
+}
+
 static void vtty_map_clear(struct tty_struct *tty)
 {
 	vtty_map_t *map = tty->driver_data;
@@ -908,28 +915,20 @@ static void vtty_map_clear(struct tty_st
 	lockdep_assert_held(&tty_mutex);
 	if (map) {
 		struct tty_struct *p = map->vttys[tty->index];
+		int i;
 
 		WARN_ON(p != (tty->driver == vttys_driver ? tty : tty->link));
 		map->vttys[tty->index] = NULL;
 		tty->driver_data = tty->link->driver_data = NULL;
-	}
-}
-
-static void vtty_map_free(vtty_map_t *map)
-{
-	int i;
 
-	lockdep_assert_held(&tty_mutex);
+		for (i = 0; i < MAX_NR_VTTY_CONSOLES; i++) {
+			if (map->vttys[i])
+				break;
+		}
 
-	for (i = 0; i < MAX_NR_VTTY_CONSOLES; i++) {
-		struct tty_struct *tty = map->vttys[i];
-		if (!tty)
-			continue;
-		tty->driver_data = tty->link->driver_data = NULL;
+		if (i >= MAX_NR_VTTY_CONSOLES)
+			vtty_map_free(map);
 	}
-
-	idr_remove(&vtty_idr, map->veid);
-	kfree(map);
 }
 
 static vtty_map_t *vtty_map_alloc(envid_t veid)
@@ -1209,24 +1208,6 @@ void vtty_release(struct tty_struct *tty
 		*o_tty_closing = 0;
 }
 
-static void ve_vtty_fini(void *data)
-{
-	struct ve_struct *ve = data;
-	vtty_map_t *map;
-
-	mutex_lock(&tty_mutex);
-	map = vtty_map_lookup(ve->veid);
-	if (map)
-		vtty_map_free(map);
-	mutex_unlock(&tty_mutex);
-}
-
-static struct ve_hook vtty_hook = {
-	.fini           = ve_vtty_fini,
-	.priority       = HOOK_PRIO_DEFAULT,
-	.owner          = THIS_MODULE,
-};
-
 static int __init vtty_init(void)
 {
 #define VTTY_DRIVER_ALLOC_FLAGS			\
@@ -1279,7 +1260,6 @@ static int __init vtty_init(void)
 	if (tty_register_driver(vttys_driver))
 		panic(pr_fmt("Can't register slave vtty driver\n"));
 
-	ve_hook_register(VE_SS_CHAIN, &vtty_hook);
 	tty_default_fops(&vtty_fops);
 	return 0;
 }