xprt.c

Linux Kernel 2.6.9 for OMAP1710

	task->tk_timeout = RPC_CONNECT_TIMEOUT;
	rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
	if (!test_and_set_bit(XPRT_CONNECTING, &xprt->sockstate)) {
		/* Note: if we are here due to a dropped connection
		 * 	 we delay reconnecting by RPC_REESTABLISH_TIMEOUT/HZ
		 * 	 seconds
		 */
		if (xprt->sock != NULL)
			schedule_delayed_work(&xprt->sock_connect,
					RPC_REESTABLISH_TIMEOUT);
		else
			schedule_work(&xprt->sock_connect);
	}
	return;
 out_write:
	xprt_release_write(xprt, task);
}

/*
 * We arrive here when awoken from waiting on connection establishment.
 */
static void
xprt_connect_status(struct rpc_task *task)
{
	struct rpc_xprt	*xprt = task->tk_xprt;

	if (task->tk_status >= 0) {
		dprintk("RPC: %4d xprt_connect_status: connection established\n",
				task->tk_pid);
		return;
	}

	/* if soft mounted, just cause this RPC to fail */
	if (RPC_IS_SOFT(task))
		task->tk_status = -EIO;

	switch (task->tk_status) {
	case -ECONNREFUSED:
	case -ECONNRESET:
	case -ENOTCONN:
		return;
	case -ETIMEDOUT:
		dprintk("RPC: %4d xprt_connect_status: timed out\n",
				task->tk_pid);
		break;
	default:
		printk(KERN_ERR "RPC: error %d connecting to server %s\n",
				-task->tk_status, task->tk_client->cl_server);
	}
	xprt_release_write(xprt, task);
}

/*
 * Look up the RPC request corresponding to a reply, and then lock it.
 */
static inline struct rpc_rqst *
xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
{
	struct list_head *pos;
	struct rpc_rqst	*req = NULL;

	list_for_each(pos, &xprt->recv) {
		struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
		if (entry->rq_xid == xid) {
			req = entry;
			break;
		}
	}
	return req;
}

/*
 * Complete reply received.
 * The TCP code relies on us to remove the request from xprt->pending.
 */
static void
xprt_complete_rqst(struct rpc_xprt *xprt, struct rpc_rqst *req, int copied)
{
	struct rpc_task	*task = req->rq_task;
	struct rpc_clnt *clnt = task->tk_client;

	/* Adjust congestion window */
	if (!xprt->nocong) {
		unsigned timer = task->tk_msg.rpc_proc->p_timer;
		xprt_adjust_cwnd(xprt, copied);
		__xprt_put_cong(xprt, req);
		if (timer) {
			if (req->rq_ntrans == 1)
				rpc_update_rtt(clnt->cl_rtt, timer,
						(long)jiffies - req->rq_xtime);
			rpc_set_timeo(clnt->cl_rtt, timer, req->rq_ntrans - 1);
		}
	}

#ifdef RPC_PROFILE
	/* Profile only reads for now */
	if (copied > 1024) {
		static unsigned long	nextstat;
		static unsigned long	pkt_rtt, pkt_len, pkt_cnt;

		pkt_cnt++;
		pkt_len += req->rq_slen + copied;
		pkt_rtt += jiffies - req->rq_xtime;
		if (time_before(nextstat, jiffies)) {
			printk("RPC: %lu %ld cwnd\n", jiffies, xprt->cwnd);
			printk("RPC: %ld %ld %ld %ld stat\n",
					jiffies, pkt_cnt, pkt_len, pkt_rtt);
			pkt_rtt = pkt_len = pkt_cnt = 0;
			nextstat = jiffies + 5 * HZ;
		}
	}
#endif

	dprintk("RPC: %4d has input (%d bytes)\n", task->tk_pid, copied);
	list_del_init(&req->rq_list);
	req->rq_received = req->rq_private_buf.len = copied;

	/* ... and wake up the process. */
	rpc_wake_up_task(task);
	return;
}

static size_t
skb_read_bits(skb_reader_t *desc, void *to, size_t len)
{
	if (len > desc->count)
		len = desc->count;
	if (skb_copy_bits(desc->skb, desc->offset, to, len))
		return 0;
	desc->count -= len;
	desc->offset += len;
	return len;
}

static size_t
skb_read_and_csum_bits(skb_reader_t *desc, void *to, size_t len)
{
	unsigned int csum2, pos;

	if (len > desc->count)
		len = desc->count;
	pos = desc->offset;
	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
	desc->csum = csum_block_add(desc->csum, csum2, pos);
	desc->count -= len;
	desc->offset += len;
	return len;
}

/*
 * We have set things up such that we perform the checksum of the UDP
 * packet in parallel with the copies into the RPC client iovec.  -DaveM
 */
int
csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
{
	skb_reader_t desc;

	desc.skb = skb;
	desc.offset = sizeof(struct udphdr);
	desc.count = skb->len - desc.offset;

	if (skb->ip_summed == CHECKSUM_UNNECESSARY)
		goto no_checksum;

	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
	xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_and_csum_bits);
	if (desc.offset != skb->len) {
		unsigned int csum2;
		csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
		desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
	}
	if (desc.count)
		return -1;
	if ((unsigned short)csum_fold(desc.csum))
		return -1;
	return 0;
no_checksum:
	xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_bits);
	if (desc.count)
		return -1;
	return 0;
}

/*
 * Input handler for RPC replies. Called from a bottom half and hence
 * atomic.
 */
static void
udp_data_ready(struct sock *sk, int len)
{
	struct rpc_task	*task;
	struct rpc_xprt	*xprt;
	struct rpc_rqst *rovr;
	struct sk_buff	*skb;
	int err, repsize, copied;
	u32 _xid, *xp;

	read_lock(&sk->sk_callback_lock);
	dprintk("RPC:      udp_data_ready...\n");
	if (!(xprt = xprt_from_sock(sk))) {
		printk("RPC:      udp_data_ready request not found!\n");
		goto out;
	}

	dprintk("RPC:      udp_data_ready client %p\n", xprt);

	if ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL)
		goto out;

	if (xprt->shutdown)
		goto dropit;

	repsize = skb->len - sizeof(struct udphdr);
	if (repsize < 4) {
		printk("RPC: impossible RPC reply size %d!\n", repsize);
		goto dropit;
	}

	/* Copy the XID from the skb... */
	xp = skb_header_pointer(skb, sizeof(struct udphdr),
				sizeof(_xid), &_xid);
	if (xp == NULL)
		goto dropit;

	/* Look up and lock the request corresponding to the given XID */
	spin_lock(&xprt->sock_lock);
	rovr = xprt_lookup_rqst(xprt, *xp);
	if (!rovr)
		goto out_unlock;
	task = rovr->rq_task;

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

	if ((copied = rovr->rq_private_buf.buflen) > repsize)
		copied = repsize;

	/* Suck it into the iovec, verify checksum if not done by hw. */
	if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb))
		goto out_unlock;

	/* Something worked... */
	dst_confirm(skb->dst);

	xprt_complete_rqst(xprt, rovr, copied);

 out_unlock:
	spin_unlock(&xprt->sock_lock);
 dropit:
	skb_free_datagram(sk, skb);
 out:
	read_unlock(&sk->sk_callback_lock);
}

/*
 * Copy from an skb into memory and shrink the skb.
 */
static inline size_t
tcp_copy_data(skb_reader_t *desc, void *p, size_t len)
{
	if (len > desc->count)
		len = desc->count;
	if (skb_copy_bits(desc->skb, desc->offset, p, len))
		return 0;
	desc->offset += len;
	desc->count -= len;
	return len;
}

/*
 * TCP read fragment marker
 */
static inline void
tcp_read_fraghdr(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	size_t len, used;
	char *p;

	p = ((char *) &xprt->tcp_recm) + xprt->tcp_offset;
	len = sizeof(xprt->tcp_recm) - xprt->tcp_offset;
	used = tcp_copy_data(desc, p, len);
	xprt->tcp_offset += used;
	if (used != len)
		return;
	xprt->tcp_reclen = ntohl(xprt->tcp_recm);
	if (xprt->tcp_reclen & 0x80000000)
		xprt->tcp_flags |= XPRT_LAST_FRAG;
	else
		xprt->tcp_flags &= ~XPRT_LAST_FRAG;
	xprt->tcp_reclen &= 0x7fffffff;
	xprt->tcp_flags &= ~XPRT_COPY_RECM;
	xprt->tcp_offset = 0;
	/* Sanity check of the record length */
	if (xprt->tcp_reclen < 4) {
		printk(KERN_ERR "RPC: Invalid TCP record fragment length\n");
		xprt_disconnect(xprt);
	}
	dprintk("RPC:      reading TCP record fragment of length %d\n",
			xprt->tcp_reclen);
}

static void
tcp_check_recm(struct rpc_xprt *xprt)
{
	if (xprt->tcp_offset == xprt->tcp_reclen) {
		xprt->tcp_flags |= XPRT_COPY_RECM;
		xprt->tcp_offset = 0;
		if (xprt->tcp_flags & XPRT_LAST_FRAG) {
			xprt->tcp_flags &= ~XPRT_COPY_DATA;
			xprt->tcp_flags |= XPRT_COPY_XID;
			xprt->tcp_copied = 0;
		}
	}
}

/*
 * TCP read xid
 */
static inline void
tcp_read_xid(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	size_t len, used;
	char *p;

	len = sizeof(xprt->tcp_xid) - xprt->tcp_offset;
	dprintk("RPC:      reading XID (%Zu bytes)\n", len);
	p = ((char *) &xprt->tcp_xid) + xprt->tcp_offset;
	used = tcp_copy_data(desc, p, len);
	xprt->tcp_offset += used;
	if (used != len)
		return;
	xprt->tcp_flags &= ~XPRT_COPY_XID;
	xprt->tcp_flags |= XPRT_COPY_DATA;
	xprt->tcp_copied = 4;
	dprintk("RPC:      reading reply for XID %08x\n", xprt->tcp_xid);
	tcp_check_recm(xprt);
}

/*
 * TCP read and complete request
 */
static inline void
tcp_read_request(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	struct rpc_rqst *req;
	struct xdr_buf *rcvbuf;
	size_t len;

	/* Find and lock the request corresponding to this xid */
	spin_lock(&xprt->sock_lock);
	req = xprt_lookup_rqst(xprt, xprt->tcp_xid);
	if (!req) {
		xprt->tcp_flags &= ~XPRT_COPY_DATA;
		dprintk("RPC:      XID %08x request not found!\n",
				xprt->tcp_xid);
		spin_unlock(&xprt->sock_lock);
		return;
	}

	rcvbuf = &req->rq_private_buf;
	len = desc->count;
	if (len > xprt->tcp_reclen - xprt->tcp_offset) {
		skb_reader_t my_desc;

		len = xprt->tcp_reclen - xprt->tcp_offset;
		memcpy(&my_desc, desc, sizeof(my_desc));
		my_desc.count = len;
		xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
					  &my_desc, tcp_copy_data);
		desc->count -= len;
		desc->offset += len;
	} else
		xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
					  desc, tcp_copy_data);
	xprt->tcp_copied += len;
	xprt->tcp_offset += len;

	if (xprt->tcp_copied == req->rq_private_buf.buflen)
		xprt->tcp_flags &= ~XPRT_COPY_DATA;
	else if (xprt->tcp_offset == xprt->tcp_reclen) {
		if (xprt->tcp_flags & XPRT_LAST_FRAG)
			xprt->tcp_flags &= ~XPRT_COPY_DATA;
	}

	if (!(xprt->tcp_flags & XPRT_COPY_DATA)) {
		dprintk("RPC: %4d received reply complete\n",
				req->rq_task->tk_pid);
		xprt_complete_rqst(xprt, req, xprt->tcp_copied);
	}
	spin_unlock(&xprt->sock_lock);
	tcp_check_recm(xprt);
}

/*
 * TCP discard extra bytes from a short read
 */
static inline void
tcp_read_discard(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	size_t len;

	len = xprt->tcp_reclen - xprt->tcp_offset;
	if (len > desc->count)
		len = desc->count;
	desc->count -= len;
	desc->offset += len;
	xprt->tcp_offset += len;
	tcp_check_recm(xprt);
}

/*
 * TCP record receive routine
 * We first have to grab the record marker, then the XID, then the data.
 */
static int
tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
		unsigned int offset, size_t len)
{
	struct rpc_xprt *xprt = rd_desc->arg.data;
	skb_reader_t desc = {
		.skb	= skb,
		.offset	= offset,
		.count	= len,
		.csum	= 0
       	};

	dprintk("RPC:      tcp_data_recv\n");
	do {
		/* Read in a new fragment marker if necessary */
		/* Can we ever really expect to get completely empty fragments? */
		if (xprt->tcp_flags & XPRT_COPY_RECM) {
			tcp_read_fraghdr(xprt, &desc);
			continue;
		}
		/* Read in the xid if necessary */
		if (xprt->tcp_flags & XPRT_COPY_XID) {
			tcp_read_xid(xprt, &desc);
			continue;
		}
		/* Read in the request data */
		if (xprt->tcp_flags & XPRT_COPY_DATA) {
			tcp_read_request(xprt, &desc);
			continue;
		}
		/* Skip over any trailing bytes on short reads */
		tcp_read_discard(xprt, &desc);
	} while (desc.count);
	dprintk("RPC:      tcp_data_recv done\n");
	return len - desc.count;
}

static void tcp_data_ready(struct sock *sk, int bytes)
{
	struct rpc_xprt *xprt;
	read_descriptor_t rd_desc;

	read_lock(&sk->sk_callback_lock);
	dprintk("RPC:      tcp_data_ready...\n");
	if (!(xprt = xprt_from_sock(sk))) {
		printk("RPC:      tcp_data_ready socket info not found!\n");
		goto out;
	}
	if (xprt->shutdown)
		goto out;

	/* We use rd_desc to pass struct xprt to tcp_data_recv */
	rd_desc.arg.data = xprt;
	rd_desc.count = 65536;
	tcp_read_sock(sk, &rd_desc, tcp_data_recv);
out:
	read_unlock(&sk->sk_callback_lock);
}

static void
tcp_state_change(struct sock *sk)
{
	struct rpc_xprt	*xprt;

	read_lock(&sk->sk_callback_lock);
	if (!(xprt = xprt_from_sock(sk)))
		goto out;
	dprintk("RPC:      tcp_state_change client %p...\n", xprt);
	dprintk("RPC:      state %x conn %d dead %d zapped %d\n",
				sk->sk_state, xprt_connected(xprt),
				sock_flag(sk, SOCK_DEAD), sk->sk_zapped);

	switch (sk->sk_state) {
	case TCP_ESTABLISHED:
		spin_lock_bh(&xprt->sock_lock);
		if (!xprt_test_and_set_connected(xprt)) {
			/* Reset TCP record info */
			xprt->tcp_offset = 0;
			xprt->tcp_reclen = 0;
			xprt->tcp_copied = 0;
			xprt->tcp_flags = XPRT_COPY_RECM | XPRT_COPY_XID;
			rpc_wake_up(&xprt->pending);
		}
		spin_unlock_bh(&xprt->sock_lock);
		break;
	case TCP_SYN_SENT:
	case TCP_SYN_RECV:
		break;
	default:
		if (xprt_test_and_clear_connected(xprt))
			rpc_wake_up_status(&xprt->pending, -ENOTCONN);
		break;
	}
 out:
	read_unlock(&sk->sk_callback_lock);
}

/*
 * Called when more output buffer space is available for this socket.
 * We try not to wake our writers until they can make "significant"
 * progress, otherwise we'll waste resources thrashing sock_sendmsg
 * with a bunch of small requests.
 */
static void
xprt_write_space(struct sock *sk)
{
	struct rpc_xprt	*xprt;
	struct socket	*sock;

	read_lock(&sk->sk_callback_lock);
	if (!(xprt = xprt_from_sock(sk)) || !(sock = sk->sk_socket))
		goto out;
	if (xprt->shutdown)
		goto out;

	/* Wait until we have enough socket memory */
	if (xprt->stream) {
		/* from net/core/stream.c:sk_stream_write_space */
		if (sk_stream_wspace(sk) < sk_stream_min_wspace(sk))
			goto out;
	} else {
		/* from net/core/sock.c:sock_def_write_space */
		if (!sock_writeable(sk))
			goto out;
	}

	if (!test_and_clear_bit(SOCK_NOSPACE, &sock->flags))
		goto out;

	spin_lock_bh(&xprt->sock_lock);
	if (xprt->snd_task && xprt->snd_task->tk_rpcwait == &xprt->pending)
		rpc_wake_up_task(xprt->snd_task);
	spin_unlock_bh(&xprt->sock_lock);
out:
	read_unlock(&sk->sk_callback_lock);
}

/*
 * RPC receive timeout handler.
 */
static void
xprt_timer(struct rpc_task *task)
{