From 5b440676c15bbe1a40f2546ec92db83ed66d9e22 Mon Sep 17 00:00:00 2001 From: Archie Pusaka Date: Tue, 14 Apr 2020 16:08:40 +0800 Subject: [PATCH] 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 Signed-off-by: Marcel Holtmann --- net/bluetooth/l2cap_sock.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 1cea42ee1e92..a995d2c51fa7 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -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);