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Bluetooth: L2CAP: add support for waiting disconnection resp 

Whenever we disconnect a L2CAP connection, we would immediately
report a disconnection event (EPOLLHUP) to the upper layer, without
waiting for the response of the other device.

This patch offers an option to wait until we receive a disconnection
response before reporting disconnection event, by using the "how"
parameter in l2cap_sock_shutdown(). Therefore, upper layer can opt
to wait for disconnection response by shutdown(sock, SHUT_WR).

This can be used to enforce proper disconnection order in HID,
where the disconnection of the interrupt channel must be complete
before attempting to disconnect the control channel.

Signed-off-by: Archie Pusaka <apusaka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Archie Pusaka 2020-04-14 16:08:40 +08:00 committed by Marcel Holtmann
parent adf1d69264
commit 5b440676c1
1 changed files with 23 additions and 7 deletions
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30
net/bluetooth/l2cap_sock.c
View File

@ -1271,14 +1271,21 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
struct l2cap_conn *conn;
int err = 0;
BT_DBG("sock %p, sk %p", sock, sk);
BT_DBG("sock %p, sk %p, how %d", sock, sk, how);
/* 'how' parameter is mapped to sk_shutdown as follows:
* SHUT_RD (0) --> RCV_SHUTDOWN (1)
* SHUT_WR (1) --> SEND_SHUTDOWN (2)
* SHUT_RDWR (2) --> SHUTDOWN_MASK (3)
*/
how++;
if (!sk)
return 0;
lock_sock(sk);
if (sk->sk_shutdown)
if ((sk->sk_shutdown & how) == how)
goto shutdown_already;
BT_DBG("Handling sock shutdown");
@ -1301,11 +1308,20 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
* has already been actioned to close the L2CAP
* link such as by l2cap_disconnection_req().
*/
if (sk->sk_shutdown)
goto has_shutdown;
if ((sk->sk_shutdown & how) == how)
goto shutdown_matched;
}
sk->sk_shutdown = SHUTDOWN_MASK;
/* Try setting the RCV_SHUTDOWN bit, return early if SEND_SHUTDOWN
* is already set
*/
if ((how & RCV_SHUTDOWN) && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
sk->sk_shutdown |= RCV_SHUTDOWN;
if ((sk->sk_shutdown & how) == how)
goto shutdown_matched;
}
sk->sk_shutdown |= SEND_SHUTDOWN;
release_sock(sk);
l2cap_chan_lock(chan);
@ -1335,7 +1351,7 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
err = bt_sock_wait_state(sk, BT_CLOSED,
sk->sk_lingertime);
has_shutdown:
shutdown_matched:
l2cap_chan_put(chan);
sock_put(sk);
@ -1363,7 +1379,7 @@ static int l2cap_sock_release(struct socket *sock)
bt_sock_unlink(&l2cap_sk_list, sk);
err = l2cap_sock_shutdown(sock, 2);
err = l2cap_sock_shutdown(sock, SHUT_RDWR);
chan = l2cap_pi(sk)->chan;
l2cap_chan_hold(chan);