xprt.c

Linux Kernel 2.6.9 for OMAP1710

	struct rpc_rqst	*req = task->tk_rqstp;
	struct rpc_xprt *xprt = req->rq_xprt;

	spin_lock(&xprt->sock_lock);
	if (req->rq_received)
		goto out;

	xprt_adjust_cwnd(req->rq_xprt, -ETIMEDOUT);
	__xprt_put_cong(xprt, req);

	dprintk("RPC: %4d xprt_timer (%s request)\n",
		task->tk_pid, req ? "pending" : "backlogged");

	task->tk_status  = -ETIMEDOUT;
out:
	task->tk_timeout = 0;
	rpc_wake_up_task(task);
	spin_unlock(&xprt->sock_lock);
}

/*
 * Place the actual RPC call.
 * We have to copy the iovec because sendmsg fiddles with its contents.
 */
int
xprt_prepare_transmit(struct rpc_task *task)
{
	struct rpc_rqst	*req = task->tk_rqstp;
	struct rpc_xprt	*xprt = req->rq_xprt;
	int err = 0;

	dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);

	if (xprt->shutdown)
		return -EIO;

	spin_lock_bh(&xprt->sock_lock);
	if (req->rq_received && !req->rq_bytes_sent) {
		err = req->rq_received;
		goto out_unlock;
	}
	if (!__xprt_lock_write(xprt, task)) {
		err = -EAGAIN;
		goto out_unlock;
	}

	if (!xprt_connected(xprt)) {
		err = -ENOTCONN;
		goto out_unlock;
	}
out_unlock:
	spin_unlock_bh(&xprt->sock_lock);
	return err;
}

void
xprt_transmit(struct rpc_task *task)
{
	struct rpc_clnt *clnt = task->tk_client;
	struct rpc_rqst	*req = task->tk_rqstp;
	struct rpc_xprt	*xprt = req->rq_xprt;
	int status, retry = 0;


	dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);

	/* set up everything as needed. */
	/* Write the record marker */
	if (xprt->stream) {
		u32	*marker = req->rq_svec[0].iov_base;

		*marker = htonl(0x80000000|(req->rq_slen-sizeof(*marker)));
	}

	smp_rmb();
	if (!req->rq_received) {
		if (list_empty(&req->rq_list)) {
			spin_lock_bh(&xprt->sock_lock);
			/* Update the softirq receive buffer */
			memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
					sizeof(req->rq_private_buf));
			/* Add request to the receive list */
			list_add_tail(&req->rq_list, &xprt->recv);
			spin_unlock_bh(&xprt->sock_lock);
			xprt_reset_majortimeo(req);
		}
	} else if (!req->rq_bytes_sent)
		return;

	/* Continue transmitting the packet/record. We must be careful
	 * to cope with writespace callbacks arriving _after_ we have
	 * called xprt_sendmsg().
	 */
	while (1) {
		req->rq_xtime = jiffies;
		status = xprt_sendmsg(xprt, req);

		if (status < 0)
			break;

		if (xprt->stream) {
			req->rq_bytes_sent += status;

			/* If we've sent the entire packet, immediately
			 * reset the count of bytes sent. */
			if (req->rq_bytes_sent >= req->rq_slen) {
				req->rq_bytes_sent = 0;
				goto out_receive;
			}
		} else {
			if (status >= req->rq_slen)
				goto out_receive;
			status = -EAGAIN;
			break;
		}

		dprintk("RPC: %4d xmit incomplete (%d left of %d)\n",
				task->tk_pid, req->rq_slen - req->rq_bytes_sent,
				req->rq_slen);

		status = -EAGAIN;
		if (retry++ > 50)
			break;
	}

	/* Note: at this point, task->tk_sleeping has not yet been set,
	 *	 hence there is no danger of the waking up task being put on
	 *	 schedq, and being picked up by a parallel run of rpciod().
	 */
	task->tk_status = status;

	switch (status) {
	case -EAGAIN:
		if (test_bit(SOCK_ASYNC_NOSPACE, &xprt->sock->flags)) {
			/* Protect against races with xprt_write_space */
			spin_lock_bh(&xprt->sock_lock);
			/* Don't race with disconnect */
			if (!xprt_connected(xprt))
				task->tk_status = -ENOTCONN;
			else if (test_bit(SOCK_NOSPACE, &xprt->sock->flags)) {
				task->tk_timeout = req->rq_timeout;
				rpc_sleep_on(&xprt->pending, task, NULL, NULL);
			}
			spin_unlock_bh(&xprt->sock_lock);
			return;
		}
		/* Keep holding the socket if it is blocked */
		rpc_delay(task, HZ>>4);
		return;
	case -ECONNREFUSED:
		task->tk_timeout = RPC_REESTABLISH_TIMEOUT;
		rpc_sleep_on(&xprt->sending, task, NULL, NULL);
	case -ENOTCONN:
		return;
	default:
		if (xprt->stream)
			xprt_disconnect(xprt);
	}
	xprt_release_write(xprt, task);
	return;
 out_receive:
	dprintk("RPC: %4d xmit complete\n", task->tk_pid);
	/* Set the task's receive timeout value */
	spin_lock_bh(&xprt->sock_lock);
	if (!xprt->nocong) {
		int timer = task->tk_msg.rpc_proc->p_timer;
		task->tk_timeout = rpc_calc_rto(clnt->cl_rtt, timer);
		task->tk_timeout <<= rpc_ntimeo(clnt->cl_rtt, timer) + req->rq_retries;
		if (task->tk_timeout > xprt->timeout.to_maxval || task->tk_timeout == 0)
			task->tk_timeout = xprt->timeout.to_maxval;
	} else
		task->tk_timeout = req->rq_timeout;
	/* Don't race with disconnect */
	if (!xprt_connected(xprt))
		task->tk_status = -ENOTCONN;
	else if (!req->rq_received)
		rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
	__xprt_release_write(xprt, task);
	spin_unlock_bh(&xprt->sock_lock);
}

/*
 * Reserve an RPC call slot.
 */
static inline void
do_xprt_reserve(struct rpc_task *task)
{
	struct rpc_xprt	*xprt = task->tk_xprt;

	task->tk_status = 0;
	if (task->tk_rqstp)
		return;
	if (!list_empty(&xprt->free)) {
		struct rpc_rqst	*req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
		list_del_init(&req->rq_list);
		task->tk_rqstp = req;
		xprt_request_init(task, xprt);
		return;
	}
	dprintk("RPC:      waiting for request slot\n");
	task->tk_status = -EAGAIN;
	task->tk_timeout = 0;
	rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
}

void
xprt_reserve(struct rpc_task *task)
{
	struct rpc_xprt	*xprt = task->tk_xprt;

	task->tk_status = -EIO;
	if (!xprt->shutdown) {
		spin_lock(&xprt->xprt_lock);
		do_xprt_reserve(task);
		spin_unlock(&xprt->xprt_lock);
		if (task->tk_rqstp)
			del_timer_sync(&xprt->timer);
	}
}

/*
 * Allocate a 'unique' XID
 */
static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
{
	return xprt->xid++;
}

static inline void xprt_init_xid(struct rpc_xprt *xprt)
{
	get_random_bytes(&xprt->xid, sizeof(xprt->xid));
}

/*
 * Initialize RPC request
 */
static void
xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
{
	struct rpc_rqst	*req = task->tk_rqstp;

	req->rq_timeout = xprt->timeout.to_initval;
	req->rq_task	= task;
	req->rq_xprt    = xprt;
	req->rq_xid     = xprt_alloc_xid(xprt);
	dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid,
			req, req->rq_xid);
}

/*
 * Release an RPC call slot
 */
void
xprt_release(struct rpc_task *task)
{
	struct rpc_xprt	*xprt = task->tk_xprt;
	struct rpc_rqst	*req;

	if (!(req = task->tk_rqstp))
		return;
	spin_lock_bh(&xprt->sock_lock);
	__xprt_release_write(xprt, task);
	__xprt_put_cong(xprt, req);
	if (!list_empty(&req->rq_list))
		list_del(&req->rq_list);
	xprt->last_used = jiffies;
	if (list_empty(&xprt->recv) && !xprt->shutdown)
		mod_timer(&xprt->timer, xprt->last_used + XPRT_IDLE_TIMEOUT);
	spin_unlock_bh(&xprt->sock_lock);
	task->tk_rqstp = NULL;
	memset(req, 0, sizeof(*req));	/* mark unused */

	dprintk("RPC: %4d release request %p\n", task->tk_pid, req);

	spin_lock(&xprt->xprt_lock);
	list_add(&req->rq_list, &xprt->free);
	xprt_clear_backlog(xprt);
	spin_unlock(&xprt->xprt_lock);
}

/*
 * Set default timeout parameters
 */
void
xprt_default_timeout(struct rpc_timeout *to, int proto)
{
	if (proto == IPPROTO_UDP)
		xprt_set_timeout(to, 5,  5 * HZ);
	else
		xprt_set_timeout(to, 5, 60 * HZ);
}

/*
 * Set constant timeout
 */
void
xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
{
	to->to_initval   = 
	to->to_increment = incr;
	to->to_maxval    = incr * retr;
	to->to_retries   = retr;
	to->to_exponential = 0;
}

unsigned int xprt_udp_slot_table_entries = RPC_DEF_SLOT_TABLE;
unsigned int xprt_tcp_slot_table_entries = RPC_DEF_SLOT_TABLE;

/*
 * Initialize an RPC client
 */
static struct rpc_xprt *
xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
{
	struct rpc_xprt	*xprt;
	unsigned int entries;
	size_t slot_table_size;
	struct rpc_rqst	*req;

	dprintk("RPC:      setting up %s transport...\n",
				proto == IPPROTO_UDP? "UDP" : "TCP");

	entries = (proto == IPPROTO_TCP)?
		xprt_tcp_slot_table_entries : xprt_udp_slot_table_entries;

	if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
		return ERR_PTR(-ENOMEM);
	memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
	xprt->max_reqs = entries;
	slot_table_size = entries * sizeof(xprt->slot[0]);
	xprt->slot = kmalloc(slot_table_size, GFP_KERNEL);
	if (xprt->slot == NULL) {
		kfree(xprt);
		return ERR_PTR(-ENOMEM);
	}
	memset(xprt->slot, 0, slot_table_size);

	xprt->addr = *ap;
	xprt->prot = proto;
	xprt->stream = (proto == IPPROTO_TCP)? 1 : 0;
	if (xprt->stream) {
		xprt->cwnd = RPC_MAXCWND(xprt);
		xprt->nocong = 1;
	} else
		xprt->cwnd = RPC_INITCWND;
	spin_lock_init(&xprt->sock_lock);
	spin_lock_init(&xprt->xprt_lock);
	init_waitqueue_head(&xprt->cong_wait);

	INIT_LIST_HEAD(&xprt->free);
	INIT_LIST_HEAD(&xprt->recv);
	INIT_WORK(&xprt->sock_connect, xprt_socket_connect, xprt);
	INIT_WORK(&xprt->task_cleanup, xprt_socket_autoclose, xprt);
	init_timer(&xprt->timer);
	xprt->timer.function = xprt_init_autodisconnect;
	xprt->timer.data = (unsigned long) xprt;
	xprt->last_used = jiffies;
	xprt->port = XPRT_MAX_RESVPORT;

	/* Set timeout parameters */
	if (to) {
		xprt->timeout = *to;
	} else
		xprt_default_timeout(&xprt->timeout, xprt->prot);

	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
	rpc_init_wait_queue(&xprt->sending, "xprt_sending");
	rpc_init_wait_queue(&xprt->resend, "xprt_resend");
	rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");

	/* initialize free list */
	for (req = &xprt->slot[entries-1]; req >= &xprt->slot[0]; req--)
		list_add(&req->rq_list, &xprt->free);

	xprt_init_xid(xprt);

	/* Check whether we want to use a reserved port */
	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;

	dprintk("RPC:      created transport %p with %u slots\n", xprt,
			xprt->max_reqs);
	
	return xprt;
}

/*
 * Bind to a reserved port
 */
static inline int xprt_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
{
	struct sockaddr_in myaddr = {
		.sin_family = AF_INET,
	};
	int		err, port;

	/* Were we already bound to a given port? Try to reuse it */
	port = xprt->port;
	do {
		myaddr.sin_port = htons(port);
		err = sock->ops->bind(sock, (struct sockaddr *) &myaddr,
						sizeof(myaddr));
		if (err == 0) {
			xprt->port = port;
			return 0;
		}
		if (--port == 0)
			port = XPRT_MAX_RESVPORT;
	} while (err == -EADDRINUSE && port != xprt->port);

	printk("RPC: Can't bind to reserved port (%d).\n", -err);
	return err;
}

static void
xprt_bind_socket(struct rpc_xprt *xprt, struct socket *sock)
{
	struct sock	*sk = sock->sk;

	if (xprt->inet)
		return;

	write_lock_bh(&sk->sk_callback_lock);
	sk->sk_user_data = xprt;
	xprt->old_data_ready = sk->sk_data_ready;
	xprt->old_state_change = sk->sk_state_change;
	xprt->old_write_space = sk->sk_write_space;
	if (xprt->prot == IPPROTO_UDP) {
		sk->sk_data_ready = udp_data_ready;
		sk->sk_no_check = UDP_CSUM_NORCV;
		xprt_set_connected(xprt);
	} else {
		struct tcp_opt *tp = tcp_sk(sk);
		tp->nonagle = 1;	/* disable Nagle's algorithm */
		sk->sk_data_ready = tcp_data_ready;
		sk->sk_state_change = tcp_state_change;
		xprt_clear_connected(xprt);
	}
	sk->sk_write_space = xprt_write_space;

	/* Reset to new socket */
	xprt->sock = sock;
	xprt->inet = sk;
	write_unlock_bh(&sk->sk_callback_lock);

	return;
}

/*
 * Set socket buffer length
 */
void
xprt_sock_setbufsize(struct rpc_xprt *xprt)
{
	struct sock *sk = xprt->inet;

	if (xprt->stream)
		return;
	if (xprt->rcvsize) {
		sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
		sk->sk_rcvbuf = xprt->rcvsize * xprt->max_reqs *  2;
	}
	if (xprt->sndsize) {
		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
		sk->sk_sndbuf = xprt->sndsize * xprt->max_reqs * 2;
		sk->sk_write_space(sk);
	}
}

/*
 * Datastream sockets are created here, but xprt_connect will create
 * and connect stream sockets.
 */
static struct socket * xprt_create_socket(struct rpc_xprt *xprt, int proto, int resvport)
{
	struct socket	*sock;
	int		type, err;

	dprintk("RPC:      xprt_create_socket(%s %d)\n",
			   (proto == IPPROTO_UDP)? "udp" : "tcp", proto);

	type = (proto == IPPROTO_UDP)? SOCK_DGRAM : SOCK_STREAM;

	if ((err = sock_create_kern(PF_INET, type, proto, &sock)) < 0) {
		printk("RPC: can't create socket (%d).\n", -err);
		return NULL;
	}

	/* If the caller has the capability, bind to a reserved port */
	if (resvport && xprt_bindresvport(xprt, sock) < 0) {
		printk("RPC: can't bind to reserved port.\n");
		goto failed;
	}

	return sock;

failed:
	sock_release(sock);
	return NULL;
}

/*
 * Create an RPC client transport given the protocol and peer address.
 */
struct rpc_xprt *
xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
{
	struct rpc_xprt	*xprt;

	xprt = xprt_setup(proto, sap, to);
	if (IS_ERR(xprt))
		dprintk("RPC:      xprt_create_proto failed\n");
	else
		dprintk("RPC:      xprt_create_proto created xprt %p\n", xprt);
	return xprt;
}

/*
 * Prepare for transport shutdown.
 */
void
xprt_shutdown(struct rpc_xprt *xprt)
{
	xprt->shutdown = 1;
	rpc_wake_up(&xprt->sending);
	rpc_wake_up(&xprt->resend);
	rpc_wake_up(&xprt->pending);
	rpc_wake_up(&xprt->backlog);
	wake_up(&xprt->cong_wait);
	del_timer_sync(&xprt->timer);
}

/*
 * Clear the xprt backlog queue
 */
int
xprt_clear_backlog(struct rpc_xprt *xprt) {
	rpc_wake_up_next(&xprt->backlog);
	wake_up(&xprt->cong_wait);
	return 1;
}

/*
 * Destroy an RPC transport, killing off all requests.
 */
int
xprt_destroy(struct rpc_xprt *xprt)
{
	dprintk("RPC:      destroying transport %p\n", xprt);
	xprt_shutdown(xprt);
	xprt_disconnect(xprt);
	xprt_close(xprt);
	kfree(xprt->slot);
	kfree(xprt);

	return 0;
}