Phonet: Pipe End Point for Phonet Pipes protocol

This protocol provides some connection handling and negotiated
congestion control. Nokia cellular modems use it for bulk transfers.
It provides packet boundaries (hence SOCK_SEQPACKET). Congestion
control is per packet rather per byte, so we do not re-use the
generic socket memory accounting.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 908 insertions, 0 deletions

diff --git a/net/phonet/pep.c b/net/phonet/pep.c
new file mode 100644
index 000000000000..c5dfecb207d2
--- /dev/null
+++ b/net/phonet/pep.c
@@ -0,0 +1,908 @@
+/*
+ * File: pep.c
+ *
+ * Phonet pipe protocol end point socket
+ *
+ * Copyright (C) 2008 Nokia Corporation.
+ *
+ * Author: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/socket.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <asm/ioctls.h>
+
+#include <linux/phonet.h>
+#include <net/phonet/phonet.h>
+#include <net/phonet/pep.h>
+
+/* sk_state values:
+ * TCP_CLOSE		sock not in use yet
+ * TCP_CLOSE_WAIT	disconnected pipe
+ * TCP_LISTEN		listening pipe endpoint
+ * TCP_SYN_RECV		connected pipe in disabled state
+ * TCP_ESTABLISHED	connected pipe in enabled state
+ *
+ * pep_sock locking:
+ *  - sk_state, ackq, hlist: sock lock needed
+ *  - listener: read only
+ *  - pipe_handle: read only
+ */
+
+#define CREDITS_MAX	10
+#define CREDITS_THR	7
+
+static const struct sockaddr_pn pipe_srv = {
+	.spn_family = AF_PHONET,
+	.spn_resource = 0xD9, /* pipe service */
+};
+
+#define pep_sb_size(s) (((s) + 5) & ~3) /* 2-bytes head, 32-bits aligned */
+
+/* Get the next TLV sub-block. */
+static unsigned char *pep_get_sb(struct sk_buff *skb, u8 *ptype, u8 *plen,
+					void *buf)
+{
+	void *data = NULL;
+	struct {
+		u8 sb_type;
+		u8 sb_len;
+	} *ph, h;
+	int buflen = *plen;
+
+	ph = skb_header_pointer(skb, 0, 2, &h);
+	if (ph == NULL || ph->sb_len < 2 || !pskb_may_pull(skb, ph->sb_len))
+		return NULL;
+	ph->sb_len -= 2;
+	*ptype = ph->sb_type;
+	*plen = ph->sb_len;
+
+	if (buflen > ph->sb_len)
+		buflen = ph->sb_len;
+	data = skb_header_pointer(skb, 2, buflen, buf);
+	__skb_pull(skb, 2 + ph->sb_len);
+	return data;
+}
+
+static int pep_reply(struct sock *sk, struct sk_buff *oskb,
+			u8 code, const void *data, int len, gfp_t priority)
+{
+	const struct pnpipehdr *oph = pnp_hdr(oskb);
+	struct pnpipehdr *ph;
+	struct sk_buff *skb;
+
+	skb = alloc_skb(MAX_PNPIPE_HEADER + len, priority);
+	if (!skb)
+		return -ENOMEM;
+	skb_set_owner_w(skb, sk);
+
+	skb_reserve(skb, MAX_PNPIPE_HEADER);
+	__skb_put(skb, len);
+	skb_copy_to_linear_data(skb, data, len);
+	__skb_push(skb, sizeof(*ph));
+	skb_reset_transport_header(skb);
+	ph = pnp_hdr(skb);
+	ph->utid = oph->utid;
+	ph->message_id = oph->message_id + 1; /* REQ -> RESP */
+	ph->pipe_handle = oph->pipe_handle;
+	ph->error_code = code;
+
+	return pn_skb_send(sk, skb, &pipe_srv);
+}
+
+#define PAD 0x00
+static int pep_accept_conn(struct sock *sk, struct sk_buff *skb)
+{
+	static const u8 data[20] = {
+		PAD, PAD, PAD, 2 /* sub-blocks */,
+		PN_PIPE_SB_REQUIRED_FC_TX, pep_sb_size(5), 3, PAD,
+			PN_MULTI_CREDIT_FLOW_CONTROL,
+			PN_ONE_CREDIT_FLOW_CONTROL,
+			PN_LEGACY_FLOW_CONTROL,
+			PAD,
+		PN_PIPE_SB_PREFERRED_FC_RX, pep_sb_size(5), 3, PAD,
+			PN_MULTI_CREDIT_FLOW_CONTROL,
+			PN_ONE_CREDIT_FLOW_CONTROL,
+			PN_LEGACY_FLOW_CONTROL,
+			PAD,
+	};
+
+	might_sleep();
+	return pep_reply(sk, skb, PN_PIPE_NO_ERROR, data, sizeof(data),
+				GFP_KERNEL);
+}
+
+static int pep_reject_conn(struct sock *sk, struct sk_buff *skb, u8 code)
+{
+	static const u8 data[4] = { PAD, PAD, PAD, 0 /* sub-blocks */ };
+	WARN_ON(code == PN_PIPE_NO_ERROR);
+	return pep_reply(sk, skb, code, data, sizeof(data), GFP_ATOMIC);
+}
+
+/* Control requests are not sent by the pipe service and have a specific
+ * message format. */
+static int pep_ctrlreq_error(struct sock *sk, struct sk_buff *oskb, u8 code)
+{
+	const struct pnpipehdr *oph = pnp_hdr(oskb);
+	struct sk_buff *skb;
+	struct pnpipehdr *ph;
+	struct sockaddr_pn dst;
+
+	skb = alloc_skb(MAX_PNPIPE_HEADER + 4, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+	skb_set_owner_w(skb, sk);
+
+	skb_reserve(skb, MAX_PHONET_HEADER);
+	ph = (struct pnpipehdr *)skb_put(skb, sizeof(*ph) + 4);
+
+	ph->utid = oph->utid;
+	ph->message_id = PNS_PEP_CTRL_RESP;
+	ph->pipe_handle = oph->pipe_handle;
+	ph->data[0] = oph->data[1]; /* CTRL id */
+	ph->data[1] = oph->data[0]; /* PEP type */
+	ph->data[2] = code; /* error code, at an usual offset */
+	ph->data[3] = PAD;
+	ph->data[4] = PAD;
+
+	pn_skb_get_src_sockaddr(oskb, &dst);
+	return pn_skb_send(sk, skb, &dst);
+}
+
+static int pipe_snd_status(struct sock *sk, u8 type, u8 status, gfp_t priority)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct pnpipehdr *ph;
+	struct sk_buff *skb;
+
+	skb = alloc_skb(MAX_PNPIPE_HEADER + 4, priority);
+	if (!skb)
+		return -ENOMEM;
+	skb_set_owner_w(skb, sk);
+
+	skb_reserve(skb, MAX_PNPIPE_HEADER + 4);
+	__skb_push(skb, sizeof(*ph) + 4);
+	skb_reset_transport_header(skb);
+	ph = pnp_hdr(skb);
+	ph->utid = 0;
+	ph->message_id = PNS_PEP_STATUS_IND;
+	ph->pipe_handle = pn->pipe_handle;
+	ph->pep_type = PN_PEP_TYPE_COMMON;
+	ph->data[1] = type;
+	ph->data[2] = PAD;
+	ph->data[3] = PAD;
+	ph->data[4] = status;
+
+	return pn_skb_send(sk, skb, &pipe_srv);
+}
+
+/* Send our RX flow control information to the sender.
+ * Socket must be locked. */
+static void pipe_grant_credits(struct sock *sk)
+{
+	struct pep_sock *pn = pep_sk(sk);
+
+	BUG_ON(sk->sk_state != TCP_ESTABLISHED);
+
+	switch (pn->rx_fc) {
+	case PN_LEGACY_FLOW_CONTROL: /* TODO */
+		break;
+	case PN_ONE_CREDIT_FLOW_CONTROL:
+		pipe_snd_status(sk, PN_PEP_IND_FLOW_CONTROL,
+				PEP_IND_READY, GFP_ATOMIC);
+		pn->rx_credits = 1;
+		break;
+	case PN_MULTI_CREDIT_FLOW_CONTROL:
+		if ((pn->rx_credits + CREDITS_THR) > CREDITS_MAX)
+			break;
+		if (pipe_snd_status(sk, PN_PEP_IND_ID_MCFC_GRANT_CREDITS,
+					CREDITS_MAX - pn->rx_credits,
+					GFP_ATOMIC) == 0)
+			pn->rx_credits = CREDITS_MAX;
+		break;
+	}
+}
+
+static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct pnpipehdr *hdr = pnp_hdr(skb);
+
+	if (!pskb_may_pull(skb, sizeof(*hdr) + 4))
+		return -EINVAL;
+
+	if (hdr->data[0] != PN_PEP_TYPE_COMMON) {
+		LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP type: %u\n",
+				(unsigned)hdr->data[0]);
+		return -EOPNOTSUPP;
+	}
+
+	switch (hdr->data[1]) {
+	case PN_PEP_IND_FLOW_CONTROL:
+		switch (pn->tx_fc) {
+		case PN_LEGACY_FLOW_CONTROL:
+			switch (hdr->data[4]) {
+			case PEP_IND_BUSY:
+				pn->tx_credits = 0;
+				break;
+			case PEP_IND_READY:
+				pn->tx_credits = 1;
+				break;
+			}
+			break;
+		case PN_ONE_CREDIT_FLOW_CONTROL:
+			if (hdr->data[4] == PEP_IND_READY)
+				pn->tx_credits = 1;
+			break;
+		}
+		break;
+
+	case PN_PEP_IND_ID_MCFC_GRANT_CREDITS:
+		if (pn->tx_fc != PN_MULTI_CREDIT_FLOW_CONTROL)
+			break;
+		if (pn->tx_credits + hdr->data[4] > 0xff)
+			pn->tx_credits = 0xff;
+		else
+			pn->tx_credits += hdr->data[4];
+		break;
+
+	default:
+		LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP indication: %u\n",
+				(unsigned)hdr->data[1]);
+		return -EOPNOTSUPP;
+	}
+	if (pn->tx_credits)
+		sk->sk_write_space(sk);
+	return 0;
+}
+
+static int pipe_rcv_created(struct sock *sk, struct sk_buff *skb)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct pnpipehdr *hdr = pnp_hdr(skb);
+	u8 n_sb = hdr->data[0];
+
+	pn->rx_fc = pn->tx_fc = PN_LEGACY_FLOW_CONTROL;
+	__skb_pull(skb, sizeof(*hdr));
+	while (n_sb > 0) {
+		u8 type, buf[2], len = sizeof(buf);
+		u8 *data = pep_get_sb(skb, &type, &len, buf);
+
+		if (data == NULL)
+			return -EINVAL;
+		switch (type) {
+		case PN_PIPE_SB_NEGOTIATED_FC:
+			if (len < 2 || (data[0] | data[1]) > 3)
+				break;
+			pn->tx_fc = data[0] & 3;
+			pn->rx_fc = data[1] & 3;
+			break;
+		}
+		n_sb--;
+	}
+	return 0;
+}
+
+/* Queue an skb to a connected sock.
+ * Socket lock must be held. */
+static int pipe_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct pnpipehdr *hdr = pnp_hdr(skb);
+	int err = 0;
+
+	BUG_ON(sk->sk_state == TCP_CLOSE_WAIT);
+
+	switch (hdr->message_id) {
+	case PNS_PEP_CONNECT_REQ:
+		pep_reject_conn(sk, skb, PN_PIPE_ERR_PEP_IN_USE);
+		break;
+
+	case PNS_PEP_DISCONNECT_REQ:
+		pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
+		sk->sk_state = TCP_CLOSE_WAIT;
+		if (!sock_flag(sk, SOCK_DEAD))
+			sk->sk_state_change(sk);
+		break;
+
+	case PNS_PEP_ENABLE_REQ:
+		/* Wait for PNS_PIPE_(ENABLED|REDIRECTED)_IND */
+		pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
+		break;
+
+	case PNS_PEP_RESET_REQ:
+		switch (hdr->state_after_reset) {
+		case PN_PIPE_DISABLE:
+			pn->init_enable = 0;
+			break;
+		case PN_PIPE_ENABLE:
+			pn->init_enable = 1;
+			break;
+		default: /* not allowed to send an error here!? */
+			err = -EINVAL;
+			goto out;
+		}
+		/* fall through */
+	case PNS_PEP_DISABLE_REQ:
+		pn->tx_credits = 0;
+		pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
+		break;
+
+	case PNS_PEP_CTRL_REQ:
+		/* TODO */
+		pep_ctrlreq_error(sk, skb, PN_PIPE_NO_ERROR);
+		break;
+
+	case PNS_PIPE_DATA:
+		__skb_pull(skb, 3); /* Pipe data header */
+		if (!pn_flow_safe(pn->rx_fc)) {
+			err = sock_queue_rcv_skb(sk, skb);
+			if (!err)
+				return 0;
+			break;
+		}
+
+		if (pn->rx_credits == 0) {
+			err = -ENOBUFS;
+			break;
+		}
+		pn->rx_credits--;
+		skb->dev = NULL;
+		skb_set_owner_r(skb, sk);
+		err = skb->len;
+		skb_queue_tail(&sk->sk_receive_queue, skb);
+		if (!sock_flag(sk, SOCK_DEAD))
+			sk->sk_data_ready(sk, err);
+		return 0;
+
+	case PNS_PEP_STATUS_IND:
+		pipe_rcv_status(sk, skb);
+		break;
+
+	case PNS_PIPE_REDIRECTED_IND:
+		err = pipe_rcv_created(sk, skb);
+		break;
+
+	case PNS_PIPE_CREATED_IND:
+		err = pipe_rcv_created(sk, skb);
+		if (err)
+			break;
+		/* fall through */
+	case PNS_PIPE_RESET_IND:
+		if (!pn->init_enable)
+			break;
+		/* fall through */
+	case PNS_PIPE_ENABLED_IND:
+		if (!pn_flow_safe(pn->tx_fc)) {
+			pn->tx_credits = 1;
+			sk->sk_write_space(sk);
+		}
+		if (sk->sk_state == TCP_ESTABLISHED)
+			break; /* Nothing to do */
+		sk->sk_state = TCP_ESTABLISHED;
+		pipe_grant_credits(sk);
+		break;
+
+	case PNS_PIPE_DISABLED_IND:
+		sk->sk_state = TCP_SYN_RECV;
+		pn->rx_credits = 0;
+		break;
+
+	default:
+		LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP message: %u\n",
+				hdr->message_id);
+		err = -EINVAL;
+	}
+out:
+	kfree_skb(skb);
+	return err;
+}
+
+/* Destroy connected sock. */
+static void pipe_destruct(struct sock *sk)
+{
+	skb_queue_purge(&sk->sk_receive_queue);
+}
+
+static int pep_connreq_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct sock *newsk;
+	struct pep_sock *newpn, *pn = pep_sk(sk);
+	struct pnpipehdr *hdr;
+	struct sockaddr_pn dst;
+	u16 peer_type;
+	u8 pipe_handle, enabled, n_sb;
+
+	if (!pskb_pull(skb, sizeof(*hdr) + 4))
+		return -EINVAL;
+
+	hdr = pnp_hdr(skb);
+	pipe_handle = hdr->pipe_handle;
+	switch (hdr->state_after_connect) {
+	case PN_PIPE_DISABLE:
+		enabled = 0;
+		break;
+	case PN_PIPE_ENABLE:
+		enabled = 1;
+		break;
+	default:
+		pep_reject_conn(sk, skb, PN_PIPE_ERR_INVALID_PARAM);
+		return -EINVAL;
+	}
+	peer_type = hdr->other_pep_type << 8;
+
+	if (unlikely(sk->sk_state != TCP_LISTEN) || sk_acceptq_is_full(sk)) {
+		pep_reject_conn(sk, skb, PN_PIPE_ERR_PEP_IN_USE);
+		return -ENOBUFS;
+	}
+
+	/* Parse sub-blocks (options) */
+	n_sb = hdr->data[4];
+	while (n_sb > 0) {
+		u8 type, buf[1], len = sizeof(buf);
+		const u8 *data = pep_get_sb(skb, &type, &len, buf);
+
+		if (data == NULL)
+			return -EINVAL;
+		switch (type) {
+		case PN_PIPE_SB_CONNECT_REQ_PEP_SUB_TYPE:
+			if (len < 1)
+				return -EINVAL;
+			peer_type = (peer_type & 0xff00) | data[0];
+			break;
+		}
+		n_sb--;
+	}
+
+	skb = skb_clone(skb, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	/* Create a new to-be-accepted sock */
+	newsk = sk_alloc(sock_net(sk), PF_PHONET, GFP_ATOMIC, sk->sk_prot);
+	if (!newsk) {
+		kfree_skb(skb);
+		return -ENOMEM;
+	}
+	sock_init_data(NULL, newsk);
+	newsk->sk_state = TCP_SYN_RECV;
+	newsk->sk_backlog_rcv = pipe_do_rcv;
+	newsk->sk_protocol = sk->sk_protocol;
+	newsk->sk_destruct = pipe_destruct;
+
+	newpn = pep_sk(newsk);
+	pn_skb_get_dst_sockaddr(skb, &dst);
+	newpn->pn_sk.sobject = pn_sockaddr_get_object(&dst);
+	newpn->pn_sk.resource = pn->pn_sk.resource;
+	newpn->pipe_handle = pipe_handle;
+	newpn->peer_type = peer_type;
+	newpn->rx_credits = newpn->tx_credits = 0;
+	newpn->rx_fc = newpn->tx_fc = PN_LEGACY_FLOW_CONTROL;
+	newpn->init_enable = enabled;
+
+	BUG_ON(!skb_queue_empty(&newsk->sk_receive_queue));
+	skb_queue_head(&newsk->sk_receive_queue, skb);
+	if (!sock_flag(sk, SOCK_DEAD))
+		sk->sk_data_ready(sk, 0);
+
+	sk_acceptq_added(sk);
+	sk_add_node(newsk, &pn->ackq);
+	return 0;
+}
+
+/* Listening sock must be locked */
+static struct sock *pep_find_pipe(const struct hlist_head *hlist,
+					const struct sockaddr_pn *dst,
+					u8 pipe_handle)
+{
+	struct hlist_node *node;
+	struct sock *sknode;
+	u16 dobj = pn_sockaddr_get_object(dst);
+
+	sk_for_each(sknode, node, hlist) {
+		struct pep_sock *pnnode = pep_sk(sknode);
+
+		/* Ports match, but addresses might not: */
+		if (pnnode->pn_sk.sobject != dobj)
+			continue;
+		if (pnnode->pipe_handle != pipe_handle)
+			continue;
+		if (sknode->sk_state == TCP_CLOSE_WAIT)
+			continue;
+
+		sock_hold(sknode);
+		return sknode;
+	}
+	return NULL;
+}
+
+/*
+ * Deliver an skb to a listening sock.
+ * Socket lock must be held.
+ * We then queue the skb to the right connected sock (if any).
+ */
+static int pep_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct sock *sknode;
+	struct pnpipehdr *hdr = pnp_hdr(skb);
+	struct sockaddr_pn dst;
+	int err = NET_RX_SUCCESS;
+	u8 pipe_handle;
+
+	if (!pskb_may_pull(skb, sizeof(*hdr)))
+		goto drop;
+
+	hdr = pnp_hdr(skb);
+	pipe_handle = hdr->pipe_handle;
+	if (pipe_handle == PN_PIPE_INVALID_HANDLE)
+		goto drop;
+
+	pn_skb_get_dst_sockaddr(skb, &dst);
+
+	/* Look for an existing pipe handle */
+	sknode = pep_find_pipe(&pn->hlist, &dst, pipe_handle);
+	if (sknode)
+		return sk_receive_skb(sknode, skb, 1);
+
+	/* Look for a pipe handle pending accept */
+	sknode = pep_find_pipe(&pn->ackq, &dst, pipe_handle);
+	if (sknode) {
+		sock_put(sknode);
+		if (net_ratelimit())
+			printk(KERN_WARNING"Phonet unconnected PEP ignored");
+		err = NET_RX_DROP;
+		goto drop;
+	}
+
+	switch (hdr->message_id) {
+	case PNS_PEP_CONNECT_REQ:
+		err = pep_connreq_rcv(sk, skb);
+		break;
+
+	case PNS_PEP_DISCONNECT_REQ:
+		pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
+		break;
+
+	case PNS_PEP_CTRL_REQ:
+		pep_ctrlreq_error(sk, skb, PN_PIPE_INVALID_HANDLE);
+		break;
+
+	case PNS_PEP_RESET_REQ:
+	case PNS_PEP_ENABLE_REQ:
+	case PNS_PEP_DISABLE_REQ:
+		/* invalid handle is not even allowed here! */
+	default:
+		err = NET_RX_DROP;
+	}
+drop:
+	kfree_skb(skb);
+	return err;
+}
+
+/* associated socket ceases to exist */
+static void pep_sock_close(struct sock *sk, long timeout)
+{
+	struct pep_sock *pn = pep_sk(sk);
+
+	sk_common_release(sk);
+
+	lock_sock(sk);
+	if (sk->sk_state == TCP_LISTEN) {
+		/* Destroy the listen queue */
+		struct sock *sknode;
+		struct hlist_node *p, *n;
+
+		sk_for_each_safe(sknode, p, n, &pn->ackq)
+			sk_del_node_init(sknode);
+		sk->sk_state = TCP_CLOSE;
+	}
+	release_sock(sk);
+}
+
+static int pep_wait_connreq(struct sock *sk, int noblock)
+{
+	struct task_struct *tsk = current;
+	struct pep_sock *pn = pep_sk(sk);
+	long timeo = sock_rcvtimeo(sk, noblock);
+
+	for (;;) {
+		DEFINE_WAIT(wait);
+
+		if (sk->sk_state != TCP_LISTEN)
+			return -EINVAL;
+		if (!hlist_empty(&pn->ackq))
+			break;
+		if (!timeo)
+			return -EWOULDBLOCK;
+		if (signal_pending(tsk))
+			return sock_intr_errno(timeo);
+
+		prepare_to_wait_exclusive(&sk->sk_socket->wait, &wait,
+						TASK_INTERRUPTIBLE);
+		release_sock(sk);
+		timeo = schedule_timeout(timeo);
+		lock_sock(sk);
+		finish_wait(&sk->sk_socket->wait, &wait);
+	}
+
+	return 0;
+}
+
+static struct sock *pep_sock_accept(struct sock *sk, int flags, int *errp)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct sock *newsk = NULL;
+	struct sk_buff *oskb;
+	int err;
+
+	lock_sock(sk);
+	err = pep_wait_connreq(sk, flags & O_NONBLOCK);
+	if (err)
+		goto out;
+
+	newsk = __sk_head(&pn->ackq);
+
+	oskb = skb_dequeue(&newsk->sk_receive_queue);
+	err = pep_accept_conn(newsk, oskb);
+	if (err) {
+		skb_queue_head(&newsk->sk_receive_queue, oskb);
+		newsk = NULL;
+		goto out;
+	}
+
+	sock_hold(sk);
+	pep_sk(newsk)->listener = sk;
+
+	sock_hold(newsk);
+	sk_del_node_init(newsk);
+	sk_acceptq_removed(sk);
+	sk_add_node(newsk, &pn->hlist);
+	__sock_put(newsk);
+
+out:
+	release_sock(sk);
+	*errp = err;
+	return newsk;
+}
+
+static int pep_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+	int answ;
+
+	switch (cmd) {
+	case SIOCINQ:
+		if (sk->sk_state == TCP_LISTEN)
+			return -EINVAL;
+
+		lock_sock(sk);
+		if (!skb_queue_empty(&sk->sk_receive_queue))
+			answ = skb_peek(&sk->sk_receive_queue)->len;
+		else
+			answ = 0;
+		release_sock(sk);
+		return put_user(answ, (int __user *)arg);
+	}
+
+	return -ENOIOCTLCMD;
+}
+
+static int pep_init(struct sock *sk)
+{
+	struct pep_sock *pn = pep_sk(sk);
+
+	INIT_HLIST_HEAD(&pn->ackq);
+	INIT_HLIST_HEAD(&pn->hlist);
+	pn->pipe_handle = PN_PIPE_INVALID_HANDLE;
+	return 0;
+}
+
+static int pep_sendmsg(struct kiocb *iocb, struct sock *sk,
+			struct msghdr *msg, size_t len)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct sk_buff *skb = NULL;
+	struct pnpipehdr *ph;
+	long timeo;
+	int flags = msg->msg_flags;
+	int err, done;
+
+	if (msg->msg_flags & MSG_OOB || !(msg->msg_flags & MSG_EOR))
+		return -EOPNOTSUPP;
+
+	lock_sock(sk);
+	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+	if ((1 << sk->sk_state) & (TCPF_LISTEN|TCPF_CLOSE)) {
+		err = -ENOTCONN;
+		goto out;
+	}
+	if (sk->sk_state != TCP_ESTABLISHED) {
+		/* Wait until the pipe gets to enabled state */
+disabled:
+		err = sk_stream_wait_connect(sk, &timeo);
+		if (err)
+			goto out;
+
+		if (sk->sk_state == TCP_CLOSE_WAIT) {
+			err = -ECONNRESET;
+			goto out;
+		}
+	}
+	BUG_ON(sk->sk_state != TCP_ESTABLISHED);
+
+	/* Wait until flow control allows TX */
+	done = pn->tx_credits > 0;
+	while (!done) {
+		DEFINE_WAIT(wait);
+
+		if (!timeo) {
+			err = -EAGAIN;
+			goto out;
+		}
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeo);
+			goto out;
+		}
+
+		prepare_to_wait(&sk->sk_socket->wait, &wait,
+				TASK_INTERRUPTIBLE);
+		done = sk_wait_event(sk, &timeo, pn->tx_credits > 0);
+		finish_wait(&sk->sk_socket->wait, &wait);
+
+		if (sk->sk_state != TCP_ESTABLISHED)
+			goto disabled;
+	}
+
+	if (!skb) {
+		skb = sock_alloc_send_skb(sk, MAX_PNPIPE_HEADER + len,
+						flags & MSG_DONTWAIT, &err);
+		if (skb == NULL)
+			goto out;
+		skb_reserve(skb, MAX_PHONET_HEADER + 3);
+
+		if (sk->sk_state != TCP_ESTABLISHED || !pn->tx_credits)
+			goto disabled; /* sock_alloc_send_skb might sleep */
+	}
+
+	err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
+	if (err < 0)
+		goto out;
+
+	__skb_push(skb, 3);
+	skb_reset_transport_header(skb);
+	ph = pnp_hdr(skb);
+	ph->utid = 0;
+	ph->message_id = PNS_PIPE_DATA;
+	ph->pipe_handle = pn->pipe_handle;
+	if (pn_flow_safe(pn->tx_fc)) /* credit-based flow control */
+		pn->tx_credits--;
+
+	err = pn_skb_send(sk, skb, &pipe_srv);
+	if (err >= 0)
+		err = len; /* success! */
+	skb = NULL;
+out:
+	release_sock(sk);
+	kfree_skb(skb);
+	return err;
+}
+
+static int pep_recvmsg(struct kiocb *iocb, struct sock *sk,
+			struct msghdr *msg, size_t len, int noblock,
+			int flags, int *addr_len)
+{
+	struct sk_buff *skb;
+	int err;
+
+	if (unlikely(flags & MSG_OOB))
+		return -EOPNOTSUPP;
+	if (unlikely(1 << sk->sk_state & (TCPF_LISTEN | TCPF_CLOSE)))
+		return -ENOTCONN;
+
+	skb = skb_recv_datagram(sk, flags, noblock, &err);
+	lock_sock(sk);
+	if (skb == NULL) {
+		if (err == -ENOTCONN && sk->sk_state == TCP_CLOSE_WAIT)
+			err = -ECONNRESET;
+		release_sock(sk);
+		return err;
+	}
+
+	if (sk->sk_state == TCP_ESTABLISHED)
+		pipe_grant_credits(sk);
+	release_sock(sk);
+
+	msg->msg_flags |= MSG_EOR;
+
+	if (skb->len > len)
+		msg->msg_flags |= MSG_TRUNC;
+	else
+		len = skb->len;
+
+	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, len);
+	if (!err)
+		err = (flags & MSG_TRUNC) ? skb->len : len;
+
+	skb_free_datagram(sk, skb);
+	return err;
+}
+
+static void pep_sock_unhash(struct sock *sk)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct sock *skparent = NULL;
+
+	lock_sock(sk);
+	if ((1 << sk->sk_state) & ~(TCPF_CLOSE|TCPF_LISTEN)) {
+		skparent = pn->listener;
+		sk_del_node_init(sk);
+		release_sock(sk);
+
+		sk = skparent;
+		pn = pep_sk(skparent);
+		lock_sock(sk);
+	}
+	/* Unhash a listening sock only when it is closed
+	 * and all of its active connected pipes are closed. */
+	if (hlist_empty(&pn->hlist))
+		pn_sock_unhash(&pn->pn_sk.sk);
+	release_sock(sk);
+
+	if (skparent)
+		sock_put(skparent);
+}
+
+static struct proto pep_proto = {
+	.close		= pep_sock_close,
+	.accept		= pep_sock_accept,
+	.ioctl		= pep_ioctl,
+	.init		= pep_init,
+	.sendmsg	= pep_sendmsg,
+	.recvmsg	= pep_recvmsg,
+	.backlog_rcv	= pep_do_rcv,
+	.hash		= pn_sock_hash,
+	.unhash		= pep_sock_unhash,
+	.get_port	= pn_sock_get_port,
+	.obj_size	= sizeof(struct pep_sock),
+	.owner		= THIS_MODULE,
+	.name		= "PNPIPE",
+};
+
+static struct phonet_protocol pep_pn_proto = {
+	.ops		= &phonet_stream_ops,
+	.prot		= &pep_proto,
+	.sock_type	= SOCK_SEQPACKET,
+};
+
+static int __init pep_register(void)
+{
+	return phonet_proto_register(PN_PROTO_PIPE, &pep_pn_proto);
+}
+
+static void __exit pep_unregister(void)
+{
+	phonet_proto_unregister(PN_PROTO_PIPE, &pep_pn_proto);
+}
+
+module_init(pep_register);
+module_exit(pep_unregister);
+MODULE_AUTHOR("Remi Denis-Courmont, Nokia");
+MODULE_DESCRIPTION("Phonet pipe protocol");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO(PF_PHONET, PN_PROTO_PIPE);