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Commit 2a9e1cfa authored by Trond Myklebust's avatar Trond Myklebust
Browse files

SUNRPC: Respond promptly to server TCP resets 

If the server sends us an RST error while we're in the TCP_ESTABLISHED
state, then that will not result in a state change, and so the RPC client
ends up hanging forever (see
http://bugzilla.kernel.org/show_bug.cgi?id=11154

)

We can intercept the reset by setting up an sk->sk_error_report callback,
which will then allow us to initiate a proper shutdown and retry...

We also make sure that if the send request receives an ECONNRESET, then we
shutdown too...

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent e946217e

net/sunrpc/xprtsock.c

+48 −10
Original line number Diff line number Diff line
@@ -249,6 +249,7 @@ struct sock_xprt { 
	void			(*old_data_ready)(struct sock *, int);

	void			(*old_state_change)(struct sock *);

	void			(*old_write_space)(struct sock *);

	void			(*old_error_report)(struct sock *);

};



/*
@@ -698,8 +699,9 @@ static int xs_tcp_send_request(struct rpc_task *task) 
	case -EAGAIN:

		xs_nospace(task);

		break;

	case -ECONNREFUSED:

	case -ECONNRESET:

		xs_tcp_shutdown(xprt);

	case -ECONNREFUSED:

	case -ENOTCONN:

	case -EPIPE:

		status = -ENOTCONN;
@@ -742,6 +744,22 @@ static void xs_tcp_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task) 
	xprt_release_xprt(xprt, task);

}



static void xs_save_old_callbacks(struct sock_xprt *transport, struct sock *sk)

{

	transport->old_data_ready = sk->sk_data_ready;

	transport->old_state_change = sk->sk_state_change;

	transport->old_write_space = sk->sk_write_space;

	transport->old_error_report = sk->sk_error_report;

}



static void xs_restore_old_callbacks(struct sock_xprt *transport, struct sock *sk)

{

	sk->sk_data_ready = transport->old_data_ready;

	sk->sk_state_change = transport->old_state_change;

	sk->sk_write_space = transport->old_write_space;

	sk->sk_error_report = transport->old_error_report;

}



/**

 * xs_close - close a socket

 * @xprt: transport
@@ -765,9 +783,8 @@ static void xs_close(struct rpc_xprt *xprt) 
	transport->sock = NULL;



	sk->sk_user_data = NULL;

	sk->sk_data_ready = transport->old_data_ready;

	sk->sk_state_change = transport->old_state_change;

	sk->sk_write_space = transport->old_write_space;



	xs_restore_old_callbacks(transport, sk);

	write_unlock_bh(&sk->sk_callback_lock);



	sk->sk_no_check = 0;
@@ -1179,6 +1196,28 @@ static void xs_tcp_state_change(struct sock *sk) 
	read_unlock(&sk->sk_callback_lock);

}



/**

 * xs_tcp_error_report - callback mainly for catching RST events

 * @sk: socket

 */

static void xs_tcp_error_report(struct sock *sk)

{

	struct rpc_xprt *xprt;



	read_lock(&sk->sk_callback_lock);

	if (sk->sk_err != ECONNRESET || sk->sk_state != TCP_ESTABLISHED)

		goto out;

	if (!(xprt = xprt_from_sock(sk)))

		goto out;

	dprintk("RPC:       %s client %p...\n"

			"RPC:       error %d\n",

			__func__, xprt, sk->sk_err);



	xprt_force_disconnect(xprt);

out:

	read_unlock(&sk->sk_callback_lock);

}



/**

 * xs_udp_write_space - callback invoked when socket buffer space

 *                             becomes available
@@ -1454,10 +1493,9 @@ static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock) 


		write_lock_bh(&sk->sk_callback_lock);



		xs_save_old_callbacks(transport, sk);



		sk->sk_user_data = xprt;

		transport->old_data_ready = sk->sk_data_ready;

		transport->old_state_change = sk->sk_state_change;

		transport->old_write_space = sk->sk_write_space;

		sk->sk_data_ready = xs_udp_data_ready;

		sk->sk_write_space = xs_udp_write_space;

		sk->sk_no_check = UDP_CSUM_NORCV;
@@ -1589,13 +1627,13 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock) 


		write_lock_bh(&sk->sk_callback_lock);



		xs_save_old_callbacks(transport, sk);



		sk->sk_user_data = xprt;

		transport->old_data_ready = sk->sk_data_ready;

		transport->old_state_change = sk->sk_state_change;

		transport->old_write_space = sk->sk_write_space;

		sk->sk_data_ready = xs_tcp_data_ready;

		sk->sk_state_change = xs_tcp_state_change;

		sk->sk_write_space = xs_tcp_write_space;

		sk->sk_error_report = xs_tcp_error_report;

		sk->sk_allocation = GFP_ATOMIC;



		/* socket options */