Patchwork [net-next-2.6,v6,08/12] net-caif: add CAIF socket implementation

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Submitter sjur.brandeland@stericsson.com
Date March 1, 2010, 12:12 p.m.
Message ID <1267445559-1911-9-git-send-email-sjur.brandeland@stericsson.com>
Download mbox | patch
Permalink /patch/46550/
State Changes Requested
Delegated to: David Miller
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Comments

sjur.brandeland@stericsson.com - March 1, 2010, 12:12 p.m.
From: Sjur Braendeland <sjur.brandeland@stericsson.com>

Implementation of CAIF sockets for protocol and address family
PF_CAIF and AF_CAIF.
CAIF socket is connection oriented implementing SOCK_SEQPACKET
interface with supporting blocking and non-blocking mode.

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
---
 net/caif/caif_socket.c | 1431 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 1431 insertions(+), 0 deletions(-)
Marcel Holtmann - March 15, 2010, 9:53 p.m.
Hi Sjur,

> +	/*
> +	 * The sock->type specifies the socket type to use. The CAIF socket is
> +	 * a packet stream in the sence that it is packet based.
> +	 * CAIF trusts the reliability of the link, no resending is implemented.
> +	 */
> +	if (sock->type != SOCK_SEQPACKET)
> +		return -ESOCKTNOSUPPORT;

we came to an interesting detail here when testing with a STE modem. Why
is this SEQPACKET and not a STREAM. Especially with the AT command
channels it is kinda weird that you have an MTU. The AT specification
doesn't really have any defined behavior when using a sequential packet
transport. It is more a stream based socket.

Regards

Marcel


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sjur.brandeland@stericsson.com - March 16, 2010, 1:27 p.m.
Hi Marcel.

Marcel Holtmann wrote:
>> +	/*
>> +	 * The sock->type specifies the socket type to use. The CAIF
>> socket is +	 * a packet stream in the sence that it is packet based.
>> +	 * CAIF trusts the reliability of the link, no resending is
>> implemented. +	 */ +	if (sock->type != SOCK_SEQPACKET)
>> +		return -ESOCKTNOSUPPORT;
> 
> we came to an interesting detail here when testing with a STE modem.
> Why is this SEQPACKET and not a STREAM.

The reason is that CAIF provides different services not just AT,
and some of them are really packet oriented such as Utility links and
Video. It would not be right to provide a stream based solution in this case.

> Especially with the AT
> command channels it is kinda weird that you have an MTU. The AT
> specification doesn't really have any defined behavior when using a
> sequential packet transport. It is more a stream based socket.

Yes I see your point. In order to limit the effort and simplify
caif_socket we ended up implementing only SEQPACKET. 

BR/Sjur
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Marcel Holtmann - March 17, 2010, 6:03 a.m.
Hi Sjur,

> >> +	 * The sock->type specifies the socket type to use. The CAIF
> >> socket is +	 * a packet stream in the sence that it is packet based.
> >> +	 * CAIF trusts the reliability of the link, no resending is
> >> implemented. +	 */ +	if (sock->type != SOCK_SEQPACKET)
> >> +		return -ESOCKTNOSUPPORT;
> > 
> > we came to an interesting detail here when testing with a STE modem.
> > Why is this SEQPACKET and not a STREAM.
> 
> The reason is that CAIF provides different services not just AT,
> and some of them are really packet oriented such as Utility links and
> Video. It would not be right to provide a stream based solution in this case.
> 
> > Especially with the AT
> > command channels it is kinda weird that you have an MTU. The AT
> > specification doesn't really have any defined behavior when using a
> > sequential packet transport. It is more a stream based socket.
> 
> Yes I see your point. In order to limit the effort and simplify
> caif_socket we ended up implementing only SEQPACKET. 

I think we need to split this. Use SEQPACKET for packet based services
and have STREAM for AT command channel.

So while this might cause internally some more code. It would take away
the complexity from userspace to turn it into a stream. And that is what
the userspace is expecting.

Regards

Marcel


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sjur.brandeland@stericsson.com - March 17, 2010, 11:04 a.m.
Hi Marcel,
>> >> +	 * The sock->type specifies the socket type to use. The CAIF

>> >> socket is +	 * a packet stream in the sence that it is packet based.

>> >> +	 * CAIF trusts the reliability of the link, no resending is

>> >> implemented. +	 */ +	if (sock->type != SOCK_SEQPACKET)

>> >> +		return -ESOCKTNOSUPPORT;

>> > 

>> > we came to an interesting detail here when testing with a STE modem.

>> > Why is this SEQPACKET and not a STREAM.

>> 

>> The reason is that CAIF provides different services not just AT,

>> and some of them are really packet oriented such as Utility links and

>> Video. It would not be right to provide a stream based solution in this case.

>> 

>> > Especially with the AT

>> > command channels it is kinda weird that you have an MTU. The AT

>> > specification doesn't really have any defined behavior when using a

>> > sequential packet transport. It is more a stream based socket.

>> 

>> Yes I see your point. In order to limit the effort and simplify

>> caif_socket we ended up implementing only SEQPACKET. 

>

>I think we need to split this. Use SEQPACKET for packet based services

>and have STREAM for AT command channel.

>So while this might cause internally some more code. It would take away

>the complexity from userspace to turn it into a stream. And that is what

>the userspace is expecting.


Ok Marcel, I'll look into supporting both STREAM and SEQPACKET.
BR/Sjur

Patch

diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
new file mode 100644
index 0000000..d499e19
--- /dev/null
+++ b/net/caif/caif_socket.c
@@ -0,0 +1,1431 @@ 
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Author:	Sjur Brendeland sjur.brandeland@stericsson.com
+ *		Per Sigmond per.sigmond@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/tcp.h>
+#include <linux/uaccess.h>
+#include <asm/atomic.h>
+
+#include <linux/caif/caif_socket.h>
+#include <net/caif/caif_layer.h>
+#include <net/caif/caif_dev.h>
+#include <net/caif/cfpkt.h>
+
+MODULE_LICENSE("GPL");
+
+
+#define CHNL_SKT_READ_QUEUE_HIGH 200
+#define CHNL_SKT_READ_QUEUE_LOW 100
+
+int caif_sockbuf_size = 40000;
+static struct kmem_cache *caif_sk_cachep;
+static atomic_t caif_nr_socks = ATOMIC_INIT(0);
+
+#define CONN_STATE_OPEN_BIT	      1
+#define CONN_STATE_PENDING_BIT	      2
+#define CONN_STATE_PEND_DESTROY_BIT   3
+#define CONN_REMOTE_SHUTDOWN_BIT      4
+
+#define TX_FLOW_ON_BIT		      1
+#define RX_FLOW_ON_BIT		      2
+
+#define STATE_IS_OPEN(cf_sk) test_bit(CONN_STATE_OPEN_BIT,\
+				    (void *) &(cf_sk)->conn_state)
+#define STATE_IS_REMOTE_SHUTDOWN(cf_sk) test_bit(CONN_REMOTE_SHUTDOWN_BIT,\
+				    (void *) &(cf_sk)->conn_state)
+#define STATE_IS_PENDING(cf_sk) test_bit(CONN_STATE_PENDING_BIT,\
+				       (void *) &(cf_sk)->conn_state)
+#define STATE_IS_PENDING_DESTROY(cf_sk) test_bit(CONN_STATE_PEND_DESTROY_BIT,\
+				       (void *) &(cf_sk)->conn_state)
+
+#define SET_STATE_PENDING_DESTROY(cf_sk) set_bit(CONN_STATE_PEND_DESTROY_BIT,\
+				    (void *) &(cf_sk)->conn_state)
+#define SET_STATE_OPEN(cf_sk) set_bit(CONN_STATE_OPEN_BIT,\
+				    (void *) &(cf_sk)->conn_state)
+#define SET_STATE_CLOSED(cf_sk) clear_bit(CONN_STATE_OPEN_BIT,\
+					(void *) &(cf_sk)->conn_state)
+#define SET_PENDING_ON(cf_sk) set_bit(CONN_STATE_PENDING_BIT,\
+				    (void *) &(cf_sk)->conn_state)
+#define SET_PENDING_OFF(cf_sk) clear_bit(CONN_STATE_PENDING_BIT,\
+				       (void *) &(cf_sk)->conn_state)
+#define SET_REMOTE_SHUTDOWN(cf_sk) set_bit(CONN_REMOTE_SHUTDOWN_BIT,\
+				    (void *) &(cf_sk)->conn_state)
+
+#define SET_REMOTE_SHUTDOWN_OFF(dev) clear_bit(CONN_REMOTE_SHUTDOWN_BIT,\
+				    (void *) &(dev)->conn_state)
+#define RX_FLOW_IS_ON(cf_sk) test_bit(RX_FLOW_ON_BIT,\
+				    (void *) &(cf_sk)->flow_state)
+#define TX_FLOW_IS_ON(cf_sk) test_bit(TX_FLOW_ON_BIT,\
+				    (void *) &(cf_sk)->flow_state)
+
+#define SET_RX_FLOW_OFF(cf_sk) clear_bit(RX_FLOW_ON_BIT,\
+				       (void *) &(cf_sk)->flow_state)
+#define SET_RX_FLOW_ON(cf_sk) set_bit(RX_FLOW_ON_BIT,\
+				    (void *) &(cf_sk)->flow_state)
+#define SET_TX_FLOW_OFF(cf_sk) clear_bit(TX_FLOW_ON_BIT,\
+				       (void *) &(cf_sk)->flow_state)
+#define SET_TX_FLOW_ON(cf_sk) set_bit(TX_FLOW_ON_BIT,\
+				    (void *) &(cf_sk)->flow_state)
+
+#define SKT_READ_FLAG 0x01
+#define SKT_WRITE_FLAG 0x02
+static struct dentry *debugfsdir;
+#include <linux/debugfs.h>
+
+#ifdef CONFIG_DEBUG_FS
+struct debug_fs_counter {
+	atomic_t num_open;
+	atomic_t num_close;
+	atomic_t num_init;
+	atomic_t num_init_resp;
+	atomic_t num_init_fail_resp;
+	atomic_t num_deinit;
+	atomic_t num_deinit_resp;
+	atomic_t num_remote_shutdown_ind;
+	atomic_t num_tx_flow_off_ind;
+	atomic_t num_tx_flow_on_ind;
+	atomic_t num_rx_flow_off;
+	atomic_t num_rx_flow_on;
+	atomic_t skb_in_use;
+	atomic_t skb_alloc;
+	atomic_t skb_free;
+};
+struct debug_fs_counter cnt;
+#define	dbfs_atomic_inc(v) atomic_inc(v)
+#define	dbfs_atomic_dec(v) atomic_dec(v)
+#else
+#define	dbfs_atomic_inc(v)
+#define	dbfs_atomic_dec(v)
+#endif
+
+/* The AF_CAIF socket */
+struct caifsock {
+	/* NOTE: sk has to be the first member */
+	struct sock sk;
+	struct cflayer layer;
+	char name[CAIF_LAYER_NAME_SZ];
+	u32 conn_state;
+	u32 flow_state;
+	struct cfpktq *pktq;
+	int file_mode;
+	struct caif_connect_request conn_req;
+	int read_queue_len;
+	spinlock_t read_queue_len_lock;
+	struct dentry *debugfs_socket_dir;
+};
+
+static void drain_queue(struct caifsock *cf_sk);
+
+/* Packet Receive Callback function called from CAIF Stack */
+static int caif_sktrecv_cb(struct cflayer *layr, struct cfpkt *pkt)
+{
+	struct caifsock *cf_sk;
+	int read_queue_high;
+	cf_sk = container_of(layr, struct caifsock, layer);
+
+	if (!STATE_IS_OPEN(cf_sk)) {
+		/*FIXME: This should be allowed finally!*/
+		pr_debug("CAIF: %s(): called after close request\n", __func__);
+		cfpkt_destroy(pkt);
+		return 0;
+	}
+	/* NOTE: This function may be called in Tasklet context! */
+
+	/* The queue has its own lock */
+	cfpkt_queue(cf_sk->pktq, pkt, 0);
+
+	spin_lock(&cf_sk->read_queue_len_lock);
+	cf_sk->read_queue_len++;
+
+	read_queue_high = (cf_sk->read_queue_len > CHNL_SKT_READ_QUEUE_HIGH);
+	spin_unlock(&cf_sk->read_queue_len_lock);
+
+	if (RX_FLOW_IS_ON(cf_sk) && read_queue_high) {
+		dbfs_atomic_inc(&cnt.num_rx_flow_off);
+		SET_RX_FLOW_OFF(cf_sk);
+
+		/* Send flow off (NOTE: must not sleep) */
+		pr_debug("CAIF: %s():"
+			" sending flow OFF (queue len = %d)\n",
+			__func__,
+		     cf_sk->read_queue_len);
+		caif_assert(cf_sk->layer.dn);
+		caif_assert(cf_sk->layer.dn->ctrlcmd);
+
+		(void) cf_sk->layer.dn->modemcmd(cf_sk->layer.dn,
+					       CAIF_MODEMCMD_FLOW_OFF_REQ);
+	}
+
+	/* Signal reader that data is available. */
+
+	wake_up_interruptible(cf_sk->sk.sk_sleep);
+
+	return 0;
+}
+
+/* Packet Flow Control Callback function called from CAIF */
+static void caif_sktflowctrl_cb(struct cflayer *layr,
+				enum caif_ctrlcmd flow,
+				int phyid)
+{
+	struct caifsock *cf_sk;
+
+	/* NOTE: This function may be called in Tasklet context! */
+	pr_debug("CAIF: %s(): flowctrl func called: %s.\n",
+		      __func__,
+		      flow == CAIF_CTRLCMD_FLOW_ON_IND ? "ON" :
+		      flow == CAIF_CTRLCMD_FLOW_OFF_IND ? "OFF" :
+		      flow == CAIF_CTRLCMD_INIT_RSP ? "INIT_RSP" :
+		      flow == CAIF_CTRLCMD_DEINIT_RSP ? "DEINIT_RSP" :
+		      flow == CAIF_CTRLCMD_INIT_FAIL_RSP ? "INIT_FAIL_RSP" :
+		      flow ==
+		      CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND ? "REMOTE_SHUTDOWN" :
+		      "UKNOWN CTRL COMMAND");
+
+	cf_sk = container_of(layr, struct caifsock, layer);
+	switch (flow) {
+	case CAIF_CTRLCMD_FLOW_ON_IND:
+		dbfs_atomic_inc(&cnt.num_tx_flow_on_ind);
+		/* Signal reader that data is available. */
+		SET_TX_FLOW_ON(cf_sk);
+		wake_up_interruptible(cf_sk->sk.sk_sleep);
+		break;
+
+	case CAIF_CTRLCMD_FLOW_OFF_IND:
+		dbfs_atomic_inc(&cnt.num_tx_flow_off_ind);
+		SET_TX_FLOW_OFF(cf_sk);
+		break;
+
+	case CAIF_CTRLCMD_INIT_RSP:
+		dbfs_atomic_inc(&cnt.num_init_resp);
+		/* Signal reader that data is available. */
+		caif_assert(STATE_IS_OPEN(cf_sk));
+		SET_PENDING_OFF(cf_sk);
+		SET_TX_FLOW_ON(cf_sk);
+		wake_up_interruptible(cf_sk->sk.sk_sleep);
+		break;
+
+	case CAIF_CTRLCMD_DEINIT_RSP:
+		dbfs_atomic_inc(&cnt.num_deinit_resp);
+		caif_assert(!STATE_IS_OPEN(cf_sk));
+		SET_PENDING_OFF(cf_sk);
+		if (!STATE_IS_PENDING_DESTROY(cf_sk)) {
+			if (cf_sk->sk.sk_sleep != NULL)
+				wake_up_interruptible(cf_sk->sk.sk_sleep);
+		}
+		dbfs_atomic_inc(&cnt.num_deinit);
+		sock_put(&cf_sk->sk);
+		wake_up_interruptible(cf_sk->sk.sk_sleep);
+		break;
+
+	case CAIF_CTRLCMD_INIT_FAIL_RSP:
+		dbfs_atomic_inc(&cnt.num_init_fail_resp);
+		caif_assert(STATE_IS_OPEN(cf_sk));
+		SET_STATE_CLOSED(cf_sk);
+		SET_PENDING_OFF(cf_sk);
+		SET_TX_FLOW_OFF(cf_sk);
+		wake_up_interruptible(cf_sk->sk.sk_sleep);
+		break;
+
+	case CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND:
+		dbfs_atomic_inc(&cnt.num_remote_shutdown_ind);
+		SET_REMOTE_SHUTDOWN(cf_sk);
+		SET_TX_FLOW_OFF(cf_sk);
+		drain_queue(cf_sk);
+		SET_RX_FLOW_ON(cf_sk);
+		cf_sk->file_mode = 0;
+		wake_up_interruptible(cf_sk->sk.sk_sleep);
+		break;
+
+	default:
+		pr_debug("CAIF: %s(): Unexpected flow command %d\n",
+			      __func__, flow);
+	}
+}
+
+static void skb_destructor(struct sk_buff *skb)
+{
+	dbfs_atomic_inc(&cnt.skb_free);
+	dbfs_atomic_dec(&cnt.skb_in_use);
+}
+
+
+static int caif_recvmsg(struct kiocb *iocb, struct socket *sock,
+				struct msghdr *m, size_t buf_len, int flags)
+
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	struct cfpkt *pkt = NULL;
+	size_t len;
+	int result;
+	struct sk_buff *skb;
+	ssize_t ret = -EIO;
+	int read_queue_low;
+
+	if (cf_sk == NULL) {
+		pr_debug("CAIF: %s(): private_data not set!\n",
+			      __func__);
+		ret = -EBADFD;
+		goto read_error;
+	}
+
+	/* Don't do multiple iovec entries yet */
+	if (m->msg_iovlen != 1)
+		return -EOPNOTSUPP;
+
+	if (unlikely(!buf_len))
+		return -EINVAL;
+
+	lock_sock(&(cf_sk->sk));
+
+	caif_assert(cf_sk->pktq);
+
+	if (!STATE_IS_OPEN(cf_sk)) {
+		/* Socket is closed or closing. */
+		if (!STATE_IS_PENDING(cf_sk)) {
+			pr_debug("CAIF: %s(): socket is closed (by remote)\n",
+				 __func__);
+			ret = -EPIPE;
+		} else {
+			pr_debug("CAIF: %s(): socket is closing..\n", __func__);
+			ret = -EBADF;
+		}
+		goto read_error;
+	}
+	/* Socket is open or opening. */
+	if (STATE_IS_PENDING(cf_sk)) {
+		pr_debug("CAIF: %s(): socket is opening...\n", __func__);
+
+		if (flags & MSG_DONTWAIT) {
+			/* We can't block. */
+			pr_debug("CAIF: %s():state pending and MSG_DONTWAIT\n",
+				 __func__);
+			ret = -EAGAIN;
+			goto read_error;
+		}
+
+		/*
+		 * Blocking mode; state is pending and we need to wait
+		 * for its conclusion.
+		 */
+		release_sock(&cf_sk->sk);
+
+		result =
+		    wait_event_interruptible(*cf_sk->sk.sk_sleep,
+					     !STATE_IS_PENDING(cf_sk));
+
+		lock_sock(&(cf_sk->sk));
+
+		if (result == -ERESTARTSYS) {
+			pr_debug("CAIF: %s(): wait_event_interruptible"
+				 " woken by a signal (1)", __func__);
+			ret = -ERESTARTSYS;
+			goto read_error;
+		}
+	}
+	if (STATE_IS_REMOTE_SHUTDOWN(cf_sk)) {
+		pr_debug("CAIF: %s(): received remote_shutdown indication\n",
+			 __func__);
+		ret = -ESHUTDOWN;
+		goto read_error;
+	}
+
+	/*
+	 * Block if we don't have any received buffers.
+	 * The queue has its own lock.
+	 */
+	while ((pkt = cfpkt_qpeek(cf_sk->pktq)) == NULL) {
+
+		if (flags & MSG_DONTWAIT) {
+			pr_debug("CAIF: %s(): MSG_DONTWAIT\n", __func__);
+			ret = -EAGAIN;
+			goto read_error;
+		}
+		trace_printk("CAIF: %s() wait_event\n", __func__);
+
+		/* Let writers in. */
+		release_sock(&cf_sk->sk);
+
+		/* Block reader until data arrives or socket is closed. */
+		if (wait_event_interruptible(*cf_sk->sk.sk_sleep,
+					cfpkt_qpeek(cf_sk->pktq)
+					|| STATE_IS_REMOTE_SHUTDOWN(cf_sk)
+					|| !STATE_IS_OPEN(cf_sk)) ==
+		    -ERESTARTSYS) {
+			pr_debug("CAIF: %s():"
+				" wait_event_interruptible woken by "
+				"a signal, signal_pending(current) = %d\n",
+				__func__,
+				signal_pending(current));
+			return -ERESTARTSYS;
+		}
+
+		trace_printk("CAIF: %s() awake\n", __func__);
+		if (STATE_IS_REMOTE_SHUTDOWN(cf_sk)) {
+			pr_debug("CAIF: %s(): "
+				 "received remote_shutdown indication\n",
+				 __func__);
+			ret = -ESHUTDOWN;
+			goto read_error_no_unlock;
+		}
+
+		/* I want to be alone on cf_sk (except status and queue). */
+		lock_sock(&(cf_sk->sk));
+
+		if (!STATE_IS_OPEN(cf_sk)) {
+			/* Someone closed the link, report error. */
+			pr_debug("CAIF: %s(): remote end shutdown!\n",
+				      __func__);
+			ret = -EPIPE;
+			goto read_error;
+		}
+	}
+
+	/* The queue has its own lock. */
+	len = cfpkt_getlen(pkt);
+
+	/* Check max length that can be copied. */
+	if (len > buf_len) {
+		pr_debug("CAIF: %s(): user buffer too small\n", __func__);
+		ret = -EINVAL;
+		goto read_error;
+	}
+
+	/*
+	 * Get packet from queue.
+	 * The queue has its own lock.
+	 */
+	pkt = cfpkt_dequeue(cf_sk->pktq);
+
+	spin_lock(&cf_sk->read_queue_len_lock);
+	cf_sk->read_queue_len--;
+	read_queue_low = (cf_sk->read_queue_len < CHNL_SKT_READ_QUEUE_LOW);
+	spin_unlock(&cf_sk->read_queue_len_lock);
+
+	if (!RX_FLOW_IS_ON(cf_sk) && read_queue_low) {
+		dbfs_atomic_inc(&cnt.num_rx_flow_on);
+		SET_RX_FLOW_ON(cf_sk);
+
+		/* Send flow on. */
+		pr_debug("CAIF: %s(): sending flow ON (queue len = %d)\n",
+			 __func__, cf_sk->read_queue_len);
+		caif_assert(cf_sk->layer.dn);
+		caif_assert(cf_sk->layer.dn->ctrlcmd);
+		(void) cf_sk->layer.dn->modemcmd(cf_sk->layer.dn,
+					       CAIF_MODEMCMD_FLOW_ON_REQ);
+
+		caif_assert(cf_sk->read_queue_len >= 0);
+	}
+
+	skb = cfpkt_tonative(pkt);
+	result = skb_copy_datagram_iovec(skb, 0, m->msg_iov, len);
+	if (result) {
+		pr_debug("CAIF: %s(): cfpkt_raw_extract failed\n", __func__);
+		cfpkt_destroy(pkt);
+		ret = -EFAULT;
+		goto read_error;
+	}
+	if (unlikely(buf_len < len)) {
+		len = buf_len;
+		m->msg_flags |= MSG_TRUNC;
+	}
+
+	/* Free packet. */
+	skb_free_datagram(sk, skb);
+
+	/* Let the others in. */
+	release_sock(&cf_sk->sk);
+	return len;
+
+read_error:
+	release_sock(&cf_sk->sk);
+read_error_no_unlock:
+	return ret;
+}
+
+/* Send a signal as a consequence of sendmsg, sendto or caif_sendmsg. */
+static int caif_sendmsg(struct kiocb *kiocb, struct socket *sock,
+			struct msghdr *msg, size_t len)
+{
+
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	void *payload;
+	size_t payload_size = msg->msg_iov->iov_len;
+	struct cfpkt *pkt = NULL;
+	struct caif_payload_info info;
+	unsigned char *txbuf;
+	ssize_t ret = -EIO;
+	int result;
+	struct sk_buff *skb;
+	caif_assert(msg->msg_iovlen == 1);
+
+	if (cf_sk == NULL) {
+		pr_debug("CAIF: %s(): private_data not set!\n",
+			      __func__);
+		ret = -EBADFD;
+		goto write_error_no_unlock;
+	}
+
+	if (unlikely(msg->msg_iov->iov_base == NULL)) {
+		pr_warning("CAIF: %s(): Buffer is NULL.\n", __func__);
+		ret = -EINVAL;
+		goto write_error_no_unlock;
+	}
+
+	payload = msg->msg_iov->iov_base;
+	if (payload_size > CAIF_MAX_PAYLOAD_SIZE) {
+		pr_debug("CAIF: %s(): buffer too long\n", __func__);
+		ret = -EINVAL;
+		goto write_error_no_unlock;
+	}
+	/* I want to be alone on cf_sk (except status and queue) */
+	lock_sock(&(cf_sk->sk));
+
+	caif_assert(cf_sk->pktq);
+
+	if (!STATE_IS_OPEN(cf_sk)) {
+		/* Socket is closed or closing */
+		if (!STATE_IS_PENDING(cf_sk)) {
+			pr_debug("CAIF: %s(): socket is closed (by remote)\n",
+				 __func__);
+			ret = -EPIPE;
+		} else {
+			pr_debug("CAIF: %s(): socket is closing...\n",
+				 __func__);
+			ret = -EBADF;
+		}
+		goto write_error;
+	}
+
+	/* Socket is open or opening */
+	if (STATE_IS_PENDING(cf_sk)) {
+		pr_debug("CAIF: %s(): socket is opening...\n", __func__);
+
+		if (msg->msg_flags & MSG_DONTWAIT) {
+			/* We can't block */
+			trace_printk("CAIF: %s():state pending:"
+				     "state=MSG_DONTWAIT\n", __func__);
+			ret = -EAGAIN;
+			goto write_error;
+		}
+
+		/* Let readers in */
+		release_sock(&cf_sk->sk);
+
+		/*
+		 * Blocking mode; state is pending and we need to wait
+		 * for its conclusion.
+		 */
+		result =
+		    wait_event_interruptible(*cf_sk->sk.sk_sleep,
+					     !STATE_IS_PENDING(cf_sk));
+
+		/* I want to be alone on cf_sk (except status and queue) */
+		lock_sock(&(cf_sk->sk));
+
+		if (result == -ERESTARTSYS) {
+			pr_debug("CAIF: %s(): wait_event_interruptible"
+				 " woken by a signal (1)", __func__);
+			ret = -ERESTARTSYS;
+			goto write_error;
+		}
+	}
+
+	if (STATE_IS_REMOTE_SHUTDOWN(cf_sk)) {
+		pr_debug("CAIF: %s(): received remote_shutdown indication\n",
+			 __func__);
+		ret = -ESHUTDOWN;
+		goto write_error;
+	}
+
+	if (!TX_FLOW_IS_ON(cf_sk)) {
+
+		/* Flow is off. Check non-block flag */
+		if (msg->msg_flags & MSG_DONTWAIT) {
+			trace_printk("CAIF: %s(): MSG_DONTWAIT and tx flow off",
+				 __func__);
+			ret = -EAGAIN;
+			goto write_error;
+		}
+
+		/* release lock before waiting */
+		release_sock(&cf_sk->sk);
+
+		/* Wait until flow is on or socket is closed */
+		if (wait_event_interruptible(*cf_sk->sk.sk_sleep,
+					TX_FLOW_IS_ON(cf_sk)
+					|| !STATE_IS_OPEN(cf_sk)
+					|| STATE_IS_REMOTE_SHUTDOWN(cf_sk)
+					) == -ERESTARTSYS) {
+			pr_debug("CAIF: %s():"
+				 " wait_event_interruptible woken by a signal",
+				 __func__);
+			ret = -ERESTARTSYS;
+			goto write_error_no_unlock;
+		}
+
+		/* I want to be alone on cf_sk (except status and queue) */
+		lock_sock(&(cf_sk->sk));
+
+		if (!STATE_IS_OPEN(cf_sk)) {
+			/* someone closed the link, report error */
+			pr_debug("CAIF: %s(): remote end shutdown!\n",
+				      __func__);
+			ret = -EPIPE;
+			goto write_error;
+		}
+
+		if (STATE_IS_REMOTE_SHUTDOWN(cf_sk)) {
+			pr_debug("CAIF: %s(): "
+				 "received remote_shutdown indication\n",
+				 __func__);
+			ret = -ESHUTDOWN;
+			goto write_error;
+		}
+	}
+
+	pkt = cfpkt_create(payload_size);
+	skb = (struct sk_buff *)pkt;
+	skb->destructor = skb_destructor;
+	skb->sk = sk;
+	dbfs_atomic_inc(&cnt.skb_alloc);
+	dbfs_atomic_inc(&cnt.skb_in_use);
+	if (cfpkt_raw_append(pkt, (void **) &txbuf, payload_size) < 0) {
+		pr_debug("CAIF: %s(): cfpkt_raw_append failed\n", __func__);
+		cfpkt_destroy(pkt);
+		ret = -EINVAL;
+		goto write_error;
+	}
+
+	/* Copy data into buffer. */
+	if (copy_from_user(txbuf, payload, payload_size)) {
+		pr_debug("CAIF: %s(): copy_from_user returned non zero.\n",
+			 __func__);
+		cfpkt_destroy(pkt);
+		ret = -EINVAL;
+		goto write_error;
+	}
+	memset(&info, 0, sizeof(info));
+
+	/* Send the packet down the stack. */
+	caif_assert(cf_sk->layer.dn);
+	caif_assert(cf_sk->layer.dn->transmit);
+
+	do {
+		ret = cf_sk->layer.dn->transmit(cf_sk->layer.dn, pkt);
+
+		if (likely((ret >= 0) || (ret != -EAGAIN)))
+			break;
+
+		/* EAGAIN - retry */
+		if (msg->msg_flags & MSG_DONTWAIT) {
+			pr_debug("CAIF: %s(): NONBLOCK and transmit failed,"
+				 " error = %d\n", __func__, ret);
+			ret = -EAGAIN;
+			goto write_error;
+		}
+
+		/* Let readers in */
+		release_sock(&cf_sk->sk);
+
+		/* Wait until flow is on or socket is closed */
+		if (wait_event_interruptible(*cf_sk->sk.sk_sleep,
+					TX_FLOW_IS_ON(cf_sk)
+					|| !STATE_IS_OPEN(cf_sk)
+					|| STATE_IS_REMOTE_SHUTDOWN(cf_sk)
+					) == -ERESTARTSYS) {
+			pr_debug("CAIF: %s(): wait_event_interruptible"
+				 " woken by a signal", __func__);
+			ret = -ERESTARTSYS;
+			goto write_error_no_unlock;
+		}
+
+		/* I want to be alone on cf_sk (except status and queue) */
+		lock_sock(&(cf_sk->sk));
+
+	} while (ret == -EAGAIN);
+
+	if (ret < 0) {
+		cfpkt_destroy(pkt);
+		pr_debug("CAIF: %s(): transmit failed, error = %d\n",
+			  __func__, ret);
+
+		goto write_error;
+	}
+
+	release_sock(&cf_sk->sk);
+	return payload_size;
+
+write_error:
+	release_sock(&cf_sk->sk);
+write_error_no_unlock:
+	return ret;
+}
+
+static unsigned int caif_poll(struct file *file, struct socket *sock,
+						poll_table *wait)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	u32 mask = 0;
+
+	poll_wait(file, sk->sk_sleep, wait);
+	lock_sock(&(cf_sk->sk));
+	if (cfpkt_qpeek(cf_sk->pktq) != NULL)
+		mask |= (POLLIN | POLLRDNORM);
+	if (!STATE_IS_OPEN(cf_sk))
+		mask |= POLLHUP;
+	else if (TX_FLOW_IS_ON(cf_sk))
+		mask |= (POLLOUT | POLLWRNORM);
+	release_sock(&cf_sk->sk);
+	trace_printk("CAIF: %s(): poll mask=0x%04x...\n",
+		      __func__, mask);
+	return mask;
+}
+
+static void drain_queue(struct caifsock *cf_sk)
+{
+	struct cfpkt *pkt = NULL;
+
+	/* Empty the queue */
+	do {
+		/* The queue has its own lock */
+		pkt = cfpkt_dequeue(cf_sk->pktq);
+		if (!pkt)
+			break;
+		pr_debug("CAIF: %s(): freeing packet from read queue\n",
+			 __func__);
+		cfpkt_destroy(pkt);
+
+	} while (1);
+
+	spin_lock(&cf_sk->read_queue_len_lock);
+	cf_sk->read_queue_len = 0;
+	spin_unlock(&cf_sk->read_queue_len_lock);
+}
+
+
+static int setsockopt(struct socket *sock,
+			int lvl, int opt, char __user *ov, unsigned int ol)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	int prio, linksel;
+	struct ifreq ifreq;
+
+	if (STATE_IS_OPEN(cf_sk)) {
+		pr_debug("CAIF: %s(): setsockopt "
+			 "cannot be done on a connected socket\n",
+			 __func__);
+		return -ENOPROTOOPT;
+	}
+	switch (opt) {
+	case CAIFSO_LINK_SELECT:
+		if (ol < sizeof(int)) {
+			pr_debug("CAIF: %s(): setsockopt"
+				 " CAIFSO_CHANNEL_CONFIG bad size\n", __func__);
+			return -EINVAL;
+		}
+		if (lvl != SOL_CAIF)
+			goto bad_sol;
+		if (copy_from_user(&linksel, ov, sizeof(int)))
+			return -EINVAL;
+		lock_sock(&(cf_sk->sk));
+		cf_sk->conn_req.link_selector = linksel;
+		release_sock(&cf_sk->sk);
+		return 0;
+
+	case SO_PRIORITY:
+		if (lvl != SOL_SOCKET)
+			goto bad_sol;
+		if (ol < sizeof(int)) {
+			pr_debug("CAIF: %s(): setsockopt"
+				 " SO_PRIORITY bad size\n", __func__);
+			return -EINVAL;
+		}
+		if (copy_from_user(&prio, ov, sizeof(int)))
+			return -EINVAL;
+		lock_sock(&(cf_sk->sk));
+		cf_sk->conn_req.priority = prio;
+		pr_debug("CAIF: %s(): Setting sockopt priority=%d\n", __func__,
+			cf_sk->conn_req.priority);
+		release_sock(&cf_sk->sk);
+		return 0;
+
+	case SO_BINDTODEVICE:
+		if (lvl != SOL_SOCKET)
+			goto bad_sol;
+		if (ol < sizeof(struct ifreq)) {
+			pr_debug("CAIF: %s(): setsockopt"
+				 " SO_PRIORITY bad size\n", __func__);
+			return -EINVAL;
+		}
+		if (copy_from_user(&ifreq, ov, sizeof(ifreq)))
+			return -EFAULT;
+		lock_sock(&(cf_sk->sk));
+		strncpy(cf_sk->conn_req.link_name, ifreq.ifr_name,
+			sizeof(cf_sk->conn_req.link_name));
+		cf_sk->conn_req.link_name
+			[sizeof(cf_sk->conn_req.link_name)-1] = 0;
+		release_sock(&cf_sk->sk);
+		return 0;
+
+	case CAIFSO_REQ_PARAM:
+		if (lvl != SOL_CAIF)
+			goto bad_sol;
+		if (cf_sk->sk.sk_protocol != CAIFPROTO_UTIL)
+			return -ENOPROTOOPT;
+		if (ol > sizeof(cf_sk->conn_req.param.data))
+			goto req_param_bad_size;
+
+		lock_sock(&(cf_sk->sk));
+		cf_sk->conn_req.param.size = ol;
+		if (copy_from_user(&cf_sk->conn_req.param.data, ov, ol)) {
+			release_sock(&cf_sk->sk);
+req_param_bad_size:
+			pr_debug("CAIF: %s(): setsockopt"
+				 " CAIFSO_CHANNEL_CONFIG bad size\n", __func__);
+			return -EINVAL;
+		}
+
+		pr_debug("CAIF: %s(): Setting reqparam len=%d "
+				"data=0x%02x%02x%02x%02x\n",
+				__func__,
+				cf_sk->conn_req.param.size,
+				cf_sk->conn_req.param.data[0],
+				cf_sk->conn_req.param.data[1],
+				cf_sk->conn_req.param.data[2],
+				cf_sk->conn_req.param.data[3]);
+		release_sock(&cf_sk->sk);
+		return 0;
+
+	default:
+		pr_debug("CAIF: %s(): unhandled option %d\n", __func__, opt);
+		return -EINVAL;
+	}
+
+	return 0;
+bad_sol:
+	pr_debug("CAIF: %s(): setsockopt bad level\n", __func__);
+	return -ENOPROTOOPT;
+
+}
+
+static int getsockopt(struct socket *sock,
+			int lvl, int opt, char __user *ov, int __user *ol)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	int len;
+	u32 val;
+	if (lvl != SOL_CAIF)
+		return -ENOPROTOOPT;
+	if (get_user(len, ol))
+		return -EFAULT;
+	if (len < 0)
+		return -EINVAL;
+	if (!STATE_IS_OPEN(cf_sk) && !STATE_IS_PENDING(cf_sk)) {
+		pr_debug("CAIF: %s():"
+			"can only be done on a sconnected socket\n",
+			 __func__);
+		return -ENOPROTOOPT;
+	}
+
+	if (ov == NULL || len < sizeof(int))
+		return -EINVAL;
+	switch (opt) {
+	default:
+		pr_debug("CAIF: %s(): unhandled option %d\n", __func__, opt);
+		return -ENOPROTOOPT;
+	}
+	if (copy_to_user(ov, &val, sizeof(val)))
+		return -EINVAL;
+
+	if (put_user(len, ol))
+		return -EFAULT;
+
+	return 0;
+}
+
+
+int caif_connect(struct socket *sock, struct sockaddr *uservaddr,
+	       int sockaddr_len, int flags)
+{
+	struct caifsock *cf_sk = NULL;
+	int result = -1;
+	int mode = 0;
+	int ret = -EIO;
+	struct sock *sk = sock->sk;
+	BUG_ON(sk == NULL);
+
+	cf_sk = container_of(sk, struct caifsock, sk);
+
+	trace_printk("CAIF: %s(): cf_sk=%p OPEN=%d, TX_FLOW=%d, RX_FLOW=%d\n",
+		 __func__, cf_sk,
+		STATE_IS_OPEN(cf_sk),
+		TX_FLOW_IS_ON(cf_sk), RX_FLOW_IS_ON(cf_sk));
+
+	sk->sk_state	= TCP_CLOSE;
+	sock->state	= SS_UNCONNECTED;
+
+	if (sock->type == SOCK_SEQPACKET) {
+		sock->state	= SS_CONNECTED;
+		sk->sk_state	= TCP_ESTABLISHED;
+	} else
+		goto out;
+
+	/* I want to be alone on cf_sk (except status and queue) */
+	lock_sock(&(cf_sk->sk));
+
+	if (sockaddr_len != sizeof(struct sockaddr_caif)) {
+		pr_debug("CAIF: %s(): Bad address len (%d,%d)\n",
+			 __func__, sockaddr_len, sizeof(struct sockaddr_caif));
+		ret = -EINVAL;
+		goto open_error;
+	}
+
+	if (uservaddr->sa_family != AF_CAIF) {
+		pr_debug("CAIF: %s(): Bad address family (%d)\n",
+			 __func__, uservaddr->sa_family);
+		ret = -EAFNOSUPPORT;
+		goto open_error;
+	}
+
+	memcpy(&cf_sk->conn_req.sockaddr, uservaddr,
+		sizeof(struct sockaddr_caif));
+
+	dbfs_atomic_inc(&cnt.num_open);
+	mode = SKT_READ_FLAG | SKT_WRITE_FLAG;
+
+	/* If socket is not open, make sure socket is in fully closed state */
+	if (!STATE_IS_OPEN(cf_sk)) {
+		/* Has link close response been received (if we ever sent it)?*/
+		if (STATE_IS_PENDING(cf_sk)) {
+			/*
+			 * Still waiting for close response from remote.
+			 * If opened non-blocking, report "would block"
+			 */
+			if (flags & MSG_DONTWAIT) {
+				pr_debug("CAIF: %s(): MSG_DONTWAIT"
+					" && close pending\n", __func__);
+				ret = -EAGAIN;
+				goto open_error;
+			}
+
+			pr_debug("CAIF: %s(): Wait for close response"
+				 " from remote...\n", __func__);
+
+			release_sock(&cf_sk->sk);
+
+			/*
+			 * Blocking mode; close is pending and we need to wait
+			 * for its conclusion.
+			 */
+			result =
+			    wait_event_interruptible(*cf_sk->sk.sk_sleep,
+						     !STATE_IS_PENDING(cf_sk));
+
+			lock_sock(&(cf_sk->sk));
+			if (result == -ERESTARTSYS) {
+				pr_debug("CAIF: %s(): wait_event_interruptible"
+					 "woken by a signal (1)", __func__);
+				ret = -ERESTARTSYS;
+				goto open_error;
+			}
+		}
+	}
+
+	/* socket is now either closed, pending open or open */
+	if (STATE_IS_OPEN(cf_sk) && !STATE_IS_PENDING(cf_sk)) {
+		/* Open */
+		pr_debug("CAIF: %s(): Socket is already opened (cf_sk=%p)"
+			" check access f_flags = 0x%x file_mode = 0x%x\n",
+			 __func__, cf_sk, mode, cf_sk->file_mode);
+
+		if (mode & cf_sk->file_mode) {
+			pr_debug("CAIF: %s(): Access mode already in use"
+				"0x%x\n",
+				__func__, mode);
+			ret = -EBUSY;
+			goto open_error;
+		}
+	} else {
+		/* We are closed or pending open.
+		 * If closed:	    send link setup
+		 * If pending open: link setup already sent (we could have been
+		 *		    interrupted by a signal last time)
+		 */
+		if (!STATE_IS_OPEN(cf_sk)) {
+			/* First opening of file; connect lower layers: */
+			/* Drain queue (very unlikely) */
+			drain_queue(cf_sk);
+
+			cf_sk->layer.receive = caif_sktrecv_cb;
+
+			SET_STATE_OPEN(cf_sk);
+			SET_PENDING_ON(cf_sk);
+
+			/* Register this channel. */
+			result =
+				caif_connect_client(&cf_sk->conn_req,
+							&cf_sk->layer);
+			if (result < 0) {
+				pr_debug("CAIF: %s(): can't register channel\n",
+					__func__);
+				ret = -EIO;
+				SET_STATE_CLOSED(cf_sk);
+				SET_PENDING_OFF(cf_sk);
+				goto open_error;
+			}
+			dbfs_atomic_inc(&cnt.num_init);
+		}
+
+		/* If opened non-blocking, report "success".
+		 */
+		if (flags & MSG_DONTWAIT) {
+			pr_debug("CAIF: %s(): MSG_DONTWAIT success\n",
+				 __func__);
+			ret = 0;
+			goto open_success;
+		}
+
+		trace_printk("CAIF: %s(): Wait for connect response\n",
+			     __func__);
+
+		/* release lock before waiting */
+		release_sock(&cf_sk->sk);
+
+		result =
+		    wait_event_interruptible(*cf_sk->sk.sk_sleep,
+					     !STATE_IS_PENDING(cf_sk));
+
+		lock_sock(&(cf_sk->sk));
+
+		if (result == -ERESTARTSYS) {
+			pr_debug("CAIF: %s(): wait_event_interruptible"
+				 "woken by a signal (2)", __func__);
+			ret = -ERESTARTSYS;
+			goto open_error;
+		}
+
+		if (!STATE_IS_OPEN(cf_sk)) {
+			/* Lower layers said "no" */
+			pr_debug("CAIF: %s(): Closed received\n", __func__);
+			ret = -EPIPE;
+			goto open_error;
+		}
+
+		trace_printk("CAIF: %s(): Connect received\n", __func__);
+	}
+open_success:
+	/* Open is ok */
+	cf_sk->file_mode |= mode;
+
+	trace_printk("CAIF: %s(): Connected - file mode = %x\n",
+		  __func__, cf_sk->file_mode);
+
+	release_sock(&cf_sk->sk);
+	return 0;
+open_error:
+	release_sock(&cf_sk->sk);
+out:
+	return ret;
+}
+
+
+static int caif_shutdown(struct socket *sock, int how)
+{
+	struct caifsock *cf_sk = NULL;
+	int result;
+	int tx_flow_state_was_on;
+	struct sock *sk = sock->sk;
+	if (how != SHUT_RDWR)
+		return -EOPNOTSUPP; /* FIXME: ENOTSUP in userland for POSIX */
+	cf_sk = container_of(sk, struct caifsock, sk);
+	if (cf_sk == NULL) {
+		pr_debug("CAIF: %s(): COULD NOT FIND SOCKET\n", __func__);
+		return -EBADF;
+	}
+	/* I want to be alone on cf_sk (except status queue) */
+	lock_sock(&(cf_sk->sk));
+	sock_hold(&cf_sk->sk);
+
+	/* IS_CLOSED have double meaning:
+	 * 1) Spontanous Remote Shutdown Request.
+	 * 2) Ack on a channel teardown(disconnect)
+	 * Must clear bit in case we previously received
+	 * remote shudown request.
+	 */
+	if (STATE_IS_OPEN(cf_sk) && !STATE_IS_PENDING(cf_sk)) {
+
+		SET_STATE_CLOSED(cf_sk);
+		SET_PENDING_ON(cf_sk);
+		sock->state = SS_DISCONNECTING;
+		tx_flow_state_was_on = TX_FLOW_IS_ON(cf_sk);
+		SET_TX_FLOW_OFF(cf_sk);
+
+		/* Hold the socket until DEINIT_RSP is received */
+		sock_hold(&cf_sk->sk);
+		result = caif_disconnect_client(&cf_sk->layer);
+
+		if (result < 0) {
+			pr_debug("CAIF: %s(): "
+					"caif_disconnect_client() failed\n",
+					 __func__);
+			SET_STATE_CLOSED(cf_sk);
+			SET_PENDING_OFF(cf_sk);
+			SET_TX_FLOW_OFF(cf_sk);
+			release_sock(&cf_sk->sk);
+			sock_put(&cf_sk->sk);
+			return -EIO;
+		}
+
+	}
+	if (STATE_IS_REMOTE_SHUTDOWN(cf_sk)) {
+		SET_PENDING_OFF(cf_sk);
+		SET_REMOTE_SHUTDOWN_OFF(cf_sk);
+	}
+	result =
+	    wait_event_interruptible(*cf_sk->sk.sk_sleep,
+				     !STATE_IS_PENDING(cf_sk));
+
+	if (result == -ERESTARTSYS) {
+		pr_debug("CAIF: %s(): wait_event_interruptible"
+			 "woken by a signal (1)", __func__);
+	}
+
+	/*
+	 * Socket is no longer in state pending close,
+	 * and we can release the reference.
+	 */
+
+	dbfs_atomic_inc(&cnt.num_close);
+	drain_queue(cf_sk);
+	SET_RX_FLOW_ON(cf_sk);
+	cf_sk->file_mode = 0;
+	sock_put(&cf_sk->sk);
+	release_sock(&cf_sk->sk);
+	return result;
+}
+
+static ssize_t caif_sock_no_sendpage(struct socket *sock,
+				     struct page *page,
+				     int offset, size_t size, int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+/* This function is called as part of close. */
+static int caif_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = NULL;
+	int res;
+
+	caif_assert(sk != NULL);
+	cf_sk = container_of(sk, struct caifsock, sk);
+
+	res = caif_shutdown(sock, SHUT_RDWR);
+	if (res)
+		return res;
+	lock_sock(&(cf_sk->sk));
+
+	sock->sk = NULL;
+
+	/* Detach the socket from its process context by making it orphan. */
+	sock_orphan(sk);
+
+	/*
+	 * Setting SHUTDOWN_MASK means that both send and receive are shutdown
+	 * for the socket.
+	 */
+	sk->sk_shutdown = SHUTDOWN_MASK;
+
+	/*
+	 * Set the socket state to closed, the TCP_CLOSE macro is used when
+	 * closing any socket.
+	 */
+	sk->sk_state = TCP_CLOSE;
+
+	/* Flush out this sockets receive queue. */
+	drain_queue(cf_sk);
+
+	/* Finally release the socket. */
+	STATE_IS_PENDING_DESTROY(cf_sk);
+	release_sock(&cf_sk->sk);
+
+	sock_put(sk);
+
+	/*
+	 * The rest of the cleanup will be handled from the
+	 * caif_sock_destructor
+	 */
+	return 0;
+}
+
+static struct proto_ops caif_ops = {
+	.family = PF_CAIF,
+	.owner = THIS_MODULE,
+	.release = caif_release,
+	.bind = sock_no_bind,
+	.connect = caif_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = sock_no_accept,
+	.getname = sock_no_getname,
+	.poll = caif_poll,
+	.ioctl = sock_no_ioctl,
+	.listen = sock_no_listen,
+	.shutdown = caif_shutdown,
+	.setsockopt = setsockopt,
+	.getsockopt = getsockopt,
+	.sendmsg = caif_sendmsg,
+	.recvmsg = caif_recvmsg,
+	.mmap = sock_no_mmap,
+	.sendpage = caif_sock_no_sendpage,
+};
+
+/* This function is called when a socket is finally destroyed. */
+static void caif_sock_destructor(struct sock *sk)
+{
+	struct caifsock *cf_sk = NULL;
+	cf_sk = container_of(sk, struct caifsock, sk);
+
+	/* Error checks. */
+	caif_assert(!atomic_read(&sk->sk_wmem_alloc));
+	caif_assert(sk_unhashed(sk));
+	caif_assert(!sk->sk_socket);
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		pr_debug("CAIF: %s(): 0x%p", __func__, sk);
+		return;
+	}
+
+	lock_sock(&(cf_sk->sk));
+
+	if (STATE_IS_OPEN(cf_sk)) {
+		pr_debug("CAIF: %s(): socket is opened (cf_sk=%p)"
+			 " file_mode = 0x%x\n", __func__,
+			 cf_sk, cf_sk->file_mode);
+		release_sock(&cf_sk->sk);
+		return;
+	}
+	drain_queue(cf_sk);
+	kfree(cf_sk->pktq);
+
+	if (cf_sk->debugfs_socket_dir != NULL)
+		debugfs_remove_recursive(cf_sk->debugfs_socket_dir);
+
+	release_sock(&cf_sk->sk);
+	trace_printk("CAIF: %s(): caif_sock_destructor: Removing socket %s\n",
+		__func__, cf_sk->name);
+	atomic_dec(&caif_nr_socks);
+}
+
+static int caif_create(struct net *net, struct socket *sock, int protocol,
+		       int kern)
+{
+	struct sock *sk = NULL;
+	struct caifsock *cf_sk = NULL;
+	int result = 0;
+	static struct proto prot = {.name = "PF_CAIF",
+		.owner = THIS_MODULE,
+		.obj_size = sizeof(struct caifsock),
+	};
+
+	/*
+	 * The sock->type specifies the socket type to use. The CAIF socket is
+	 * a packet stream in the sence that it is packet based.
+	 * CAIF trusts the reliability of the link, no resending is implemented.
+	 */
+	if (sock->type != SOCK_SEQPACKET)
+		return -ESOCKTNOSUPPORT;
+	prot.slab = caif_sk_cachep;
+
+	if (net != &init_net)
+		return -EAFNOSUPPORT;
+
+	if (protocol < 0 || protocol >= CAIFPROTO_MAX)
+		return -EPROTONOSUPPORT;
+	/*
+	 * Set the socket state to unconnected.	 The socket state is really
+	 * not used at all in the net/core or socket.c but the
+	 * initialization makes sure that sock->state is not uninitialized.
+	 */
+	sock->state = SS_UNCONNECTED;
+
+	sk = sk_alloc(net, PF_CAIF, GFP_KERNEL, &prot);
+	if (!sk)
+		return -ENOMEM;
+
+	cf_sk = container_of(sk, struct caifsock, sk);
+
+	/* Store the protocol */
+	sk->sk_protocol = (unsigned char) protocol;
+
+	spin_lock_init(&cf_sk->read_queue_len_lock);
+
+	/* Fill in some information concerning the misc socket. */
+	snprintf(cf_sk->name, sizeof(cf_sk->name), "cf_sk%d",
+		atomic_read(&caif_nr_socks));
+
+	/*
+	 * Lock in order to try to stop someone from opening the socket
+	 * too early.
+	 */
+	lock_sock(&(cf_sk->sk));
+
+	/* Initialize the nozero default sock structure data. */
+	sock_init_data(sock, sk);
+	sock->ops = &caif_ops;
+	sk->sk_destruct = caif_sock_destructor;
+	sk->sk_sndbuf = caif_sockbuf_size;
+	sk->sk_rcvbuf = caif_sockbuf_size;
+
+	cf_sk->pktq = cfpktq_create();
+
+	if (!cf_sk->pktq) {
+		pr_err("CAIF: %s(): queue create failed.\n", __func__);
+		result = -ENOMEM;
+		release_sock(&cf_sk->sk);
+		goto err_failed;
+	}
+	cf_sk->layer.ctrlcmd = caif_sktflowctrl_cb;
+	SET_STATE_CLOSED(cf_sk);
+	SET_PENDING_OFF(cf_sk);
+	SET_TX_FLOW_OFF(cf_sk);
+	SET_RX_FLOW_ON(cf_sk);
+
+	/* Set default options on configuration */
+	cf_sk->conn_req.priority = CAIF_PRIO_NORMAL;
+	cf_sk->conn_req.link_selector = CAIF_LINK_HIGH_BANDW;
+	cf_sk->conn_req.protocol = protocol;
+	/* Increase the number of sockets created. */
+	atomic_inc(&caif_nr_socks);
+	if (!IS_ERR(debugfsdir)) {
+		cf_sk->debugfs_socket_dir =
+			debugfs_create_dir(cf_sk->name, debugfsdir);
+		debugfs_create_u32("conn_state", S_IRUSR | S_IWUSR,
+				cf_sk->debugfs_socket_dir, &cf_sk->conn_state);
+		debugfs_create_u32("flow_state", S_IRUSR | S_IWUSR,
+				cf_sk->debugfs_socket_dir, &cf_sk->flow_state);
+		debugfs_create_u32("read_queue_len", S_IRUSR | S_IWUSR,
+				cf_sk->debugfs_socket_dir,
+				(u32 *) &cf_sk->read_queue_len);
+		debugfs_create_u32("identity", S_IRUSR | S_IWUSR,
+				cf_sk->debugfs_socket_dir,
+				(u32 *) &cf_sk->layer.id);
+	}
+	release_sock(&cf_sk->sk);
+	return 0;
+err_failed:
+	sk_free(sk);
+	return result;
+}
+
+
+static struct net_proto_family caif_family_ops = {
+	.family = PF_CAIF,
+	.create = caif_create,
+	.owner = THIS_MODULE,
+};
+
+int af_caif_init(void)
+{
+	int err;
+	err = sock_register(&caif_family_ops);
+
+	if (!err)
+		return err;
+
+	return 0;
+}
+
+static int __init caif_sktinit_module(void)
+{
+	int stat;
+#ifdef CONFIG_DEBUG_FS
+	debugfsdir = debugfs_create_dir("chnl_skt", NULL);
+	if (!IS_ERR(debugfsdir)) {
+		debugfs_create_u32("skb_inuse", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.skb_in_use);
+		debugfs_create_u32("skb_alloc", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.skb_alloc);
+		debugfs_create_u32("skb_free", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.skb_free);
+		debugfs_create_u32("num_sockets", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &caif_nr_socks);
+		debugfs_create_u32("num_open", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_open);
+		debugfs_create_u32("num_close", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_close);
+		debugfs_create_u32("num_init", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_init);
+		debugfs_create_u32("num_init_resp", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_init_resp);
+		debugfs_create_u32("num_init_fail_resp", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_init_fail_resp);
+		debugfs_create_u32("num_deinit", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_deinit);
+		debugfs_create_u32("num_deinit_resp", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_deinit_resp);
+		debugfs_create_u32("num_remote_shutdown_ind",
+				S_IRUSR | S_IWUSR, debugfsdir,
+				(u32 *) &cnt.num_remote_shutdown_ind);
+		debugfs_create_u32("num_tx_flow_off_ind", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_tx_flow_off_ind);
+		debugfs_create_u32("num_tx_flow_on_ind", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_tx_flow_on_ind);
+		debugfs_create_u32("num_rx_flow_off", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_rx_flow_off);
+		debugfs_create_u32("num_rx_flow_on", S_IRUSR | S_IWUSR,
+				debugfsdir,
+				(u32 *) &cnt.num_rx_flow_on);
+	}
+#endif
+	stat = af_caif_init();
+	if (stat) {
+		pr_err("CAIF: %s(): Failed to initialize CAIF socket layer.",
+		       __func__);
+		return stat;
+	}
+	return 0;
+}
+
+static void __exit caif_sktexit_module(void)
+{
+	sock_unregister(PF_CAIF);
+	if (debugfsdir != NULL)
+		debugfs_remove_recursive(debugfsdir);
+}
+
+module_init(caif_sktinit_module);
+module_exit(caif_sktexit_module);
+