Merge branch 'tcp_bh_fixes'

Eric Dumazet says:

====================
net: block BH in TCP callbacks

Four layers using TCP stack were assuming sk_callback_lock could
be locked using read_lock() in their handlers because TCP stack
was running with BH disabled.

This is no longer the case. Since presumably the rest could
also depend on BH being disabled, just use read_lock_bh().

Then each layer might consider switching to RCU protection
and no longer depend on BH.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/scsi/iscsi_tcp.c

@@ -131,10 +131,10 @@ static void iscsi_sw_tcp_data_ready(struct sock *sk)
 	struct iscsi_tcp_conn *tcp_conn;
 	read_descriptor_t rd_desc;
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	conn = sk->sk_user_data;
 	if (!conn) {
-		read_unlock(&sk->sk_callback_lock);
+		read_unlock_bh(&sk->sk_callback_lock);
 		return;
 	}
 	tcp_conn = conn->dd_data;
@@ -154,7 +154,7 @@ static void iscsi_sw_tcp_data_ready(struct sock *sk)
 	/* If we had to (atomically) map a highmem page,
 	 * unmap it now. */
 	iscsi_tcp_segment_unmap(&tcp_conn->in.segment);
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 }
 
 static void iscsi_sw_tcp_state_change(struct sock *sk)
@@ -165,10 +165,10 @@ static void iscsi_sw_tcp_state_change(struct sock *sk)
 	struct iscsi_session *session;
 	void (*old_state_change)(struct sock *);
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	conn = sk->sk_user_data;
 	if (!conn) {
-		read_unlock(&sk->sk_callback_lock);
+		read_unlock_bh(&sk->sk_callback_lock);
 		return;
 	}
 	session = conn->session;
@@ -179,7 +179,7 @@ static void iscsi_sw_tcp_state_change(struct sock *sk)
 	tcp_sw_conn = tcp_conn->dd_data;
 	old_state_change = tcp_sw_conn->old_state_change;
 
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 
 	old_state_change(sk);
 }

fs/ocfs2/cluster/tcp.c

@@ -600,10 +600,11 @@ static void o2net_set_nn_state(struct o2net_node *nn,
 static void o2net_data_ready(struct sock *sk)
 {
 	void (*ready)(struct sock *sk);
+	struct o2net_sock_container *sc;
 
-	read_lock(&sk->sk_callback_lock);
-	if (sk->sk_user_data) {
-		struct o2net_sock_container *sc = sk->sk_user_data;
+	read_lock_bh(&sk->sk_callback_lock);
+	sc = sk->sk_user_data;
+	if (sc) {
 		sclog(sc, "data_ready hit\n");
 		o2net_set_data_ready_time(sc);
 		o2net_sc_queue_work(sc, &sc->sc_rx_work);
@@ -611,7 +612,7 @@ static void o2net_data_ready(struct sock *sk)
 	} else {
 		ready = sk->sk_data_ready;
 	}
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 
 	ready(sk);
 }
@@ -622,7 +623,7 @@ static void o2net_state_change(struct sock *sk)
 	void (*state_change)(struct sock *sk);
 	struct o2net_sock_container *sc;
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	sc = sk->sk_user_data;
 	if (sc == NULL) {
 		state_change = sk->sk_state_change;
@@ -649,7 +650,7 @@ static void o2net_state_change(struct sock *sk)
 		break;
 	}
 out:
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 	state_change(sk);
 }
 
@@ -2012,7 +2013,7 @@ static void o2net_listen_data_ready(struct sock *sk)
 {
 	void (*ready)(struct sock *sk);
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	ready = sk->sk_user_data;
 	if (ready == NULL) { /* check for teardown race */
 		ready = sk->sk_data_ready;
@@ -2039,7 +2040,7 @@ static void o2net_listen_data_ready(struct sock *sk)
 	}
 
 out:
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 	if (ready != NULL)
 		ready(sk);
 }

net/rds/tcp_connect.c

@@ -43,7 +43,7 @@ void rds_tcp_state_change(struct sock *sk)
 	struct rds_connection *conn;
 	struct rds_tcp_connection *tc;
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	conn = sk->sk_user_data;
 	if (!conn) {
 		state_change = sk->sk_state_change;
@@ -69,7 +69,7 @@ void rds_tcp_state_change(struct sock *sk)
 			break;
 	}
 out:
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 	state_change(sk);
 }
 

net/rds/tcp_listen.c

@@ -166,7 +166,7 @@ void rds_tcp_listen_data_ready(struct sock *sk)
 
 	rdsdebug("listen data ready sk %p\n", sk);
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	ready = sk->sk_user_data;
 	if (!ready) { /* check for teardown race */
 		ready = sk->sk_data_ready;
@@ -183,7 +183,7 @@ void rds_tcp_listen_data_ready(struct sock *sk)
 		rds_tcp_accept_work(sk);
 
 out:
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 	ready(sk);
 }
 

net/rds/tcp_recv.c

@@ -301,7 +301,7 @@ void rds_tcp_data_ready(struct sock *sk)
 
 	rdsdebug("data ready sk %p\n", sk);
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	conn = sk->sk_user_data;
 	if (!conn) { /* check for teardown race */
 		ready = sk->sk_data_ready;
@@ -315,7 +315,7 @@ void rds_tcp_data_ready(struct sock *sk)
 	if (rds_tcp_read_sock(conn, GFP_ATOMIC) == -ENOMEM)
 		queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
 out:
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 	ready(sk);
 }
 

net/rds/tcp_send.c

@@ -180,7 +180,7 @@ void rds_tcp_write_space(struct sock *sk)
 	struct rds_connection *conn;
 	struct rds_tcp_connection *tc;
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	conn = sk->sk_user_data;
 	if (!conn) {
 		write_space = sk->sk_write_space;
@@ -200,7 +200,7 @@ void rds_tcp_write_space(struct sock *sk)
 		queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 
 out:
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 
 	/*
 	 * write_space is only called when data leaves tcp's send queue if

net/tipc/server.c

@@ -138,28 +138,28 @@ static void sock_data_ready(struct sock *sk)
 {
 	struct tipc_conn *con;
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	con = sock2con(sk);
 	if (con && test_bit(CF_CONNECTED, &con->flags)) {
 		conn_get(con);
 		if (!queue_work(con->server->rcv_wq, &con->rwork))
 			conn_put(con);
 	}
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 }
 
 static void sock_write_space(struct sock *sk)
 {
 	struct tipc_conn *con;
 
-	read_lock(&sk->sk_callback_lock);
+	read_lock_bh(&sk->sk_callback_lock);
 	con = sock2con(sk);
 	if (con && test_bit(CF_CONNECTED, &con->flags)) {
 		conn_get(con);
 		if (!queue_work(con->server->send_wq, &con->swork))
 			conn_put(con);
 	}
-	read_unlock(&sk->sk_callback_lock);
+	read_unlock_bh(&sk->sk_callback_lock);
 }
 
 static void tipc_register_callbacks(struct socket *sock, struct tipc_conn *con)