Bluetooth: Reinitialize the list after deletion for session user list

From: Tedd Ho-Jeong An <[email protected]>

If the user->list is deleted with list_del(), it doesn't initialize the entry which can cause the issue with list_empty(). According to the comment from the list.h, list_empty() returns false even if the list is empty and put the entry in an undefined state.

/**
* list_del - deletes entry from list.
* @entry: the element to delete from the list.
* Note: list_empty() on entry does not return true after this, the entry is
* in an undefined state.
*/

Because of this behavior, list_empty() returns false even if list is empty when the device is reconnected.

So, user->list needs to be re-initialized after list_del(). list.h already have a macro list_del_init() which deletes the entry and initailze it again.

---
 net/bluetooth/l2cap_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 51594fb..45fffa4 100644
@@ -1634,7 +1634,7 @@ void l2cap_unregister_user(struct l2cap_conn *conn, s=

truct l2cap_user *user)
if (list_empty(&user->list))
goto out_unlock;
=20
- list_del(&user->list);
+ list_del_init(&user->list);
user->remove(conn, user);
=20
out_unlock:
@@ -1648,7 +1648,7 @@ static void l2cap_unregister_all_users(struct l2cap_c= onn *conn)
=20
while (!list_empty(&conn->users)) {
user =3D list_first_entry(&conn->users, struct l2cap_user, list);
- list_del(&user->list);
+ list_del_init(&user->list);
user->remove(conn, user);
}
}
--=20
2.1.0

Hi Tedd,

patch has been applied to bluetooth-stable tree.

Regards

Marcel