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caif: Use link layer MTU instead of fixed MTU 

Previously CAIF supported maximum transfer size of ~4050.
The transfer size is now calculated dynamically based on the
link layers mtu size.

Signed-off-by: Sjur Braendeland@stericsson.com
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sjur Braendeland 2010-06-17 06:55:40 +00:00 committed by David S. Miller
parent a7da1f55a8
commit 2aa40aef9d
15 changed files with 173 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/caif/caif_serial.c
View File

@ -403,7 +403,6 @@ static void caifdev_setup(struct net_device *dev)
dev->type = ARPHRD_CAIF;
dev->flags = IFF_POINTOPOINT | IFF_NOARP;
dev->mtu = CAIF_MAX_MTU;
dev->hard_header_len = CAIF_NEEDED_HEADROOM;
dev->tx_queue_len = 0;
dev->destructor = free_netdev;
skb_queue_head_init(&serdev->head);

8
include/net/caif/caif_dev.h
View File

@ -50,6 +50,9 @@ struct caif_connect_request {
* @client_layer: User implementation of client layer. This layer
* MUST have receive and control callback functions
* implemented.
* @ifindex: Link layer interface index used for this connection.
* @headroom: Head room needed by CAIF protocol.
* @tailroom: Tail room needed by CAIF protocol.
*
* This function connects a CAIF channel. The Client must implement
* the struct cflayer. This layer represents the Client layer and holds
@ -59,8 +62,9 @@ struct caif_connect_request {
* E.g. CAIF Socket will call this function for each socket it connects
* and have one client_layer instance for each socket.
*/
int caif_connect_client(struct caif_connect_request *config,
struct cflayer *client_layer);
int caif_connect_client(struct caif_connect_request *conn_req,
struct cflayer *client_layer, int *ifindex,
int *headroom, int *tailroom);
/**
* caif_disconnect_client - Disconnects a client from the CAIF stack.

6
include/net/caif/caif_layer.h
View File

@ -15,14 +15,8 @@ struct cfpktq;
struct caif_payload_info;
struct caif_packet_funcs;
#define CAIF_MAX_FRAMESIZE 4096
#define CAIF_MAX_PAYLOAD_SIZE (4096 - 64)
#define CAIF_NEEDED_HEADROOM (10)
#define CAIF_NEEDED_TAILROOM (2)
#define CAIF_LAYER_NAME_SZ 16
#define CAIF_SUCCESS 1
#define CAIF_FAILURE 0
/**
* caif_assert() - Assert function for CAIF.

16
include/net/caif/cfcnfg.h
View File

@ -7,6 +7,7 @@
#ifndef CFCNFG_H_
#define CFCNFG_H_
#include <linux/spinlock.h>
#include <linux/netdevice.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfctrl.h>
@ -73,8 +74,8 @@ void cfcnfg_remove(struct cfcnfg *cfg);
void
cfcnfg_add_phy_layer(struct cfcnfg *cnfg, enum cfcnfg_phy_type phy_type,
void *dev, struct cflayer *phy_layer, u16 *phyid,
enum cfcnfg_phy_preference pref,
struct net_device *dev, struct cflayer *phy_layer,
u16 *phyid, enum cfcnfg_phy_preference pref,
bool fcs, bool stx);
/**
@ -114,11 +115,18 @@ void cfcnfg_release_adap_layer(struct cflayer *adap_layer);
* @param: Link setup parameters.
* @adap_layer: Specify the adaptation layer; the receive and
* flow-control functions MUST be set in the structure.
*
* @ifindex: Link layer interface index used for this connection.
* @proto_head: Protocol head-space needed by CAIF protocol,
* excluding link layer.
* @proto_tail: Protocol tail-space needed by CAIF protocol,
* excluding link layer.
*/
int cfcnfg_add_adaptation_layer(struct cfcnfg *cnfg,
struct cfctrl_link_param *param,
struct cflayer *adap_layer);
struct cflayer *adap_layer,
int *ifindex,
int *proto_head,
int *proto_tail);
/**
* cfcnfg_get_phyid() - Get physical ID, given type.

12
net/caif/caif_dev.c
View File

@ -255,7 +255,7 @@ static int caif_device_notify(struct notifier_block *me, unsigned long what,
pref = CFPHYPREF_HIGH_BW;
break;
}
dev_hold(dev);
cfcnfg_add_phy_layer(get_caif_conf(),
phy_type,
dev,
@ -285,6 +285,7 @@ static int caif_device_notify(struct notifier_block *me, unsigned long what,
caifd->layer.up->ctrlcmd(caifd->layer.up,
_CAIF_CTRLCMD_PHYIF_DOWN_IND,
caifd->layer.id);
might_sleep();
res = wait_event_interruptible_timeout(caifd->event,
atomic_read(&caifd->in_use) == 0,
TIMEOUT);
@ -300,6 +301,7 @@ static int caif_device_notify(struct notifier_block *me, unsigned long what,
"Unregistering an active CAIF device: %s\n",
__func__, dev->name);
cfcnfg_del_phy_layer(get_caif_conf(), &caifd->layer);
dev_put(dev);
atomic_set(&caifd->state, what);
break;
@ -326,7 +328,8 @@ struct cfcnfg *get_caif_conf(void)
EXPORT_SYMBOL(get_caif_conf);
int caif_connect_client(struct caif_connect_request *conn_req,
struct cflayer *client_layer)
struct cflayer *client_layer, int *ifindex,
int *headroom, int *tailroom)
{
struct cfctrl_link_param param;
int ret;
@ -334,8 +337,9 @@ int caif_connect_client(struct caif_connect_request *conn_req,
if (ret)
return ret;
/* Hook up the adaptation layer. */
return cfcnfg_add_adaptation_layer(get_caif_conf(),
&param, client_layer);
return cfcnfg_add_adaptation_layer(get_caif_conf(), &param,
client_layer, ifindex,
headroom, tailroom);
}
EXPORT_SYMBOL(caif_connect_client);

54
net/caif/caif_socket.c
View File

@ -28,8 +28,8 @@
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(AF_CAIF);
#define CAIF_DEF_SNDBUF (CAIF_MAX_PAYLOAD_SIZE*10)
#define CAIF_DEF_RCVBUF (CAIF_MAX_PAYLOAD_SIZE*100)
#define CAIF_DEF_SNDBUF (4096*10)
#define CAIF_DEF_RCVBUF (4096*100)
/*
* CAIF state is re-using the TCP socket states.
@ -76,6 +76,7 @@ struct caifsock {
struct caif_connect_request conn_req;
struct mutex readlock;
struct dentry *debugfs_socket_dir;
int headroom, tailroom, maxframe;
};
static int rx_flow_is_on(struct caifsock *cf_sk)
@ -594,23 +595,32 @@ static int caif_seqpkt_sendmsg(struct kiocb *kiocb, struct socket *sock,
goto err;
noblock = msg->msg_flags & MSG_DONTWAIT;
buffer_size = len + CAIF_NEEDED_HEADROOM + CAIF_NEEDED_TAILROOM;
timeo = sock_sndtimeo(sk, noblock);
timeo = caif_wait_for_flow_on(container_of(sk, struct caifsock, sk),
1, timeo, &ret);
if (ret)
goto err;
ret = -EPIPE;
if (cf_sk->sk.sk_state != CAIF_CONNECTED ||
sock_flag(sk, SOCK_DEAD) ||
(sk->sk_shutdown & RCV_SHUTDOWN))
goto err;
/* Error if trying to write more than maximum frame size. */
ret = -EMSGSIZE;
if (len > cf_sk->maxframe && cf_sk->sk.sk_protocol != CAIFPROTO_RFM)
goto err;
buffer_size = len + cf_sk->headroom + cf_sk->tailroom;
ret = -ENOMEM;
skb = sock_alloc_send_skb(sk, buffer_size, noblock, &ret);
if (!skb)
if (!skb || skb_tailroom(skb) < buffer_size)
goto err;
skb_reserve(skb, CAIF_NEEDED_HEADROOM);
skb_reserve(skb, cf_sk->headroom);
ret = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
@ -641,7 +651,6 @@ static int caif_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
long timeo;
err = -EOPNOTSUPP;
if (unlikely(msg->msg_flags&MSG_OOB))
goto out_err;
@ -658,8 +667,8 @@ static int caif_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
size = len-sent;
if (size > CAIF_MAX_PAYLOAD_SIZE)
size = CAIF_MAX_PAYLOAD_SIZE;
if (size > cf_sk->maxframe)
size = cf_sk->maxframe;
/* If size is more than half of sndbuf, chop up message */
if (size > ((sk->sk_sndbuf >> 1) - 64))
@ -669,14 +678,14 @@ static int caif_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
size = SKB_MAX_ALLOC;
skb = sock_alloc_send_skb(sk,
size + CAIF_NEEDED_HEADROOM
+ CAIF_NEEDED_TAILROOM,
size + cf_sk->headroom +
cf_sk->tailroom,
msg->msg_flags&MSG_DONTWAIT,
&err);
if (skb == NULL)
goto out_err;
skb_reserve(skb, CAIF_NEEDED_HEADROOM);
skb_reserve(skb, cf_sk->headroom);
/*
* If you pass two values to the sock_alloc_send_skb
* it tries to grab the large buffer with GFP_NOFS
@ -817,17 +826,15 @@ static int caif_connect(struct socket *sock, struct sockaddr *uaddr,
struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
long timeo;
int err;
int ifindex, headroom, tailroom;
struct net_device *dev;
lock_sock(sk);
err = -EAFNOSUPPORT;
if (uaddr->sa_family != AF_CAIF)
goto out;
err = -ESOCKTNOSUPPORT;
if (unlikely(!(sk->sk_type == SOCK_STREAM &&
cf_sk->sk.sk_protocol == CAIFPROTO_AT) &&
sk->sk_type != SOCK_SEQPACKET))
goto out;
switch (sock->state) {
case SS_UNCONNECTED:
/* Normal case, a fresh connect */
@ -883,12 +890,23 @@ static int caif_connect(struct socket *sock, struct sockaddr *uaddr,
dbfs_atomic_inc(&cnt.num_connect_req);
cf_sk->layer.receive = caif_sktrecv_cb;
err = caif_connect_client(&cf_sk->conn_req,
&cf_sk->layer);
&cf_sk->layer, &ifindex, &headroom, &tailroom);
if (err < 0) {
cf_sk->sk.sk_socket->state = SS_UNCONNECTED;
cf_sk->sk.sk_state = CAIF_DISCONNECTED;
goto out;
}
dev = dev_get_by_index(sock_net(sk), ifindex);
cf_sk->headroom = LL_RESERVED_SPACE_EXTRA(dev, headroom);
cf_sk->tailroom = tailroom;
cf_sk->maxframe = dev->mtu - (headroom + tailroom);
dev_put(dev);
if (cf_sk->maxframe < 1) {
pr_warning("CAIF: %s(): CAIF Interface MTU too small (%d)\n",
__func__, dev->mtu);
err = -ENODEV;
goto out;
}
err = -EINPROGRESS;
wait_connect:

44
net/caif/cfcnfg.c
View File

@ -6,6 +6,7 @@
#include <linux/kernel.h>
#include <linux/stddef.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfpkt.h>
#include <net/caif/cfcnfg.h>
@ -42,6 +43,15 @@ struct cfcnfg_phyinfo {
/* Information about the physical device */
struct dev_info dev_info;
/* Interface index */
int ifindex;
/* Use Start of frame extension */
bool use_stx;
/* Use Start of frame checksum */
bool use_fcs;
};
struct cfcnfg {
@ -249,9 +259,20 @@ static void cfcnfg_linkdestroy_rsp(struct cflayer *layer, u8 channel_id)
{
}
int protohead[CFCTRL_SRV_MASK] = {
[CFCTRL_SRV_VEI] = 4,
[CFCTRL_SRV_DATAGRAM] = 7,
[CFCTRL_SRV_UTIL] = 4,
[CFCTRL_SRV_RFM] = 3,
[CFCTRL_SRV_DBG] = 3,
};
int cfcnfg_add_adaptation_layer(struct cfcnfg *cnfg,
struct cfctrl_link_param *param,
struct cflayer *adap_layer)
struct cflayer *adap_layer,
int *ifindex,
int *proto_head,
int *proto_tail)
{
struct cflayer *frml;
if (adap_layer == NULL) {
@ -277,6 +298,14 @@ int cfcnfg_add_adaptation_layer(struct cfcnfg *cnfg,
param->phyid);
caif_assert(cnfg->phy_layers[param->phyid].phy_layer->id ==
param->phyid);
*ifindex = cnfg->phy_layers[param->phyid].ifindex;
*proto_head =
protohead[param->linktype]+
(cnfg->phy_layers[param->phyid].use_stx ? 1 : 0);
*proto_tail = 2;
/* FIXME: ENUMERATE INITIALLY WHEN ACTIVATING PHYSICAL INTERFACE */
cfctrl_enum_req(cnfg->ctrl, param->phyid);
return cfctrl_linkup_request(cnfg->ctrl, param, adap_layer);
@ -298,6 +327,8 @@ cfcnfg_linkup_rsp(struct cflayer *layer, u8 channel_id, enum cfctrl_srv serv,
struct cfcnfg *cnfg = container_obj(layer);
struct cflayer *servicel = NULL;
struct cfcnfg_phyinfo *phyinfo;
struct net_device *netdev;
if (adapt_layer == NULL) {
pr_debug("CAIF: %s(): link setup response "
"but no client exist, send linkdown back\n",
@ -329,8 +360,9 @@ cfcnfg_linkup_rsp(struct cflayer *layer, u8 channel_id, enum cfctrl_srv serv,
servicel = cfdgml_create(channel_id, &phyinfo->dev_info);
break;
case CFCTRL_SRV_RFM:
netdev = phyinfo->dev_info.dev;
servicel = cfrfml_create(channel_id, &phyinfo->dev_info,
RFM_FRAGMENT_SIZE);
netdev->mtu);
break;
case CFCTRL_SRV_UTIL:
servicel = cfutill_create(channel_id, &phyinfo->dev_info);
@ -361,8 +393,8 @@ cfcnfg_linkup_rsp(struct cflayer *layer, u8 channel_id, enum cfctrl_srv serv,
void
cfcnfg_add_phy_layer(struct cfcnfg *cnfg, enum cfcnfg_phy_type phy_type,
void *dev, struct cflayer *phy_layer, u16 *phyid,
enum cfcnfg_phy_preference pref,
struct net_device *dev, struct cflayer *phy_layer,
u16 *phyid, enum cfcnfg_phy_preference pref,
bool fcs, bool stx)
{
struct cflayer *frml;
@ -416,6 +448,10 @@ cfcnfg_add_phy_layer(struct cfcnfg *cnfg, enum cfcnfg_phy_type phy_type,
cnfg->phy_layers[*phyid].dev_info.dev = dev;
cnfg->phy_layers[*phyid].phy_layer = phy_layer;
cnfg->phy_layers[*phyid].phy_ref_count = 0;
cnfg->phy_layers[*phyid].ifindex = dev->ifindex;
cnfg->phy_layers[*phyid].use_stx = stx;
cnfg->phy_layers[*phyid].use_fcs = fcs;
phy_layer->type = phy_type;
frml = cffrml_create(*phyid, fcs);
if (!frml) {

6
net/caif/cfctrl.c
View File

@ -19,7 +19,7 @@
#ifdef CAIF_NO_LOOP
static int handle_loop(struct cfctrl *ctrl,
int cmd, struct cfpkt *pkt){
return CAIF_FAILURE;
return -1;
}
#else
static int handle_loop(struct cfctrl *ctrl,
@ -395,7 +395,7 @@ static int cfctrl_recv(struct cflayer *layer, struct cfpkt *pkt)
cmd = cmdrsp & CFCTRL_CMD_MASK;
if (cmd != CFCTRL_CMD_LINK_ERR
&& CFCTRL_RSP_BIT != (CFCTRL_RSP_BIT & cmdrsp)) {
if (handle_loop(cfctrl, cmd, pkt) == CAIF_FAILURE)
if (handle_loop(cfctrl, cmd, pkt) != 0)
cmdrsp |= CFCTRL_ERR_BIT;
}
@ -647,6 +647,6 @@ found:
default:
break;
}
return CAIF_SUCCESS;
return 0;
}
#endif

5
net/caif/cfdgml.c
View File

@ -17,6 +17,7 @@
#define DGM_FLOW_OFF 0x81
#define DGM_FLOW_ON 0x80
#define DGM_CTRL_PKT_SIZE 1
#define DGM_MTU 1500
static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
@ -89,6 +90,10 @@ static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
if (!cfsrvl_ready(service, &ret))
return ret;
/* STE Modem cannot handle more than 1500 bytes datagrams */
if (cfpkt_getlen(pkt) > DGM_MTU)
return -EMSGSIZE;
cfpkt_add_head(pkt, &zero, 4);
/* Add info for MUX-layer to route the packet out. */

4
net/caif/cfpkt_skbuff.c
View File

@ -9,8 +9,8 @@
#include <linux/hardirq.h>
#include <net/caif/cfpkt.h>
#define PKT_PREFIX CAIF_NEEDED_HEADROOM
#define PKT_POSTFIX CAIF_NEEDED_TAILROOM
#define PKT_PREFIX 16
#define PKT_POSTFIX 2
#define PKT_LEN_WHEN_EXTENDING 128
#define PKT_ERROR(pkt, errmsg) do { \
cfpkt_priv(pkt)->erronous = true; \

7
net/caif/cfserl.c
View File

@ -14,7 +14,8 @@
#define container_obj(layr) ((struct cfserl *) layr)
#define CFSERL_STX 0x02
#define CAIF_MINIUM_PACKET_SIZE 4
#define SERIAL_MINIUM_PACKET_SIZE 4
#define SERIAL_MAX_FRAMESIZE 4096
struct cfserl {
struct cflayer layer;
struct cfpkt *incomplete_frm;
@ -119,8 +120,8 @@ static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
/*
* Frame error handling
*/
if (expectlen < CAIF_MINIUM_PACKET_SIZE
|| expectlen > CAIF_MAX_FRAMESIZE) {
if (expectlen < SERIAL_MINIUM_PACKET_SIZE
|| expectlen > SERIAL_MAX_FRAMESIZE) {
if (!layr->usestx) {
if (pkt != NULL)
cfpkt_destroy(pkt);

1
net/caif/cfsrvl.c
View File

@ -162,7 +162,6 @@ void cfservl_destroy(struct cflayer *layer)
void cfsrvl_release(struct kref *kref)
{
struct cfsrvl *service = container_of(kref, struct cfsrvl, ref);
pr_info("CAIF: %s(): enter\n", __func__);
kfree(service);
}

6
net/caif/cfutill.c
View File

@ -90,12 +90,6 @@ static int cfutill_transmit(struct cflayer *layr, struct cfpkt *pkt)
if (!cfsrvl_ready(service, &ret))
return ret;
if (cfpkt_getlen(pkt) > CAIF_MAX_PAYLOAD_SIZE) {
pr_err("CAIF: %s(): packet too large size=%d\n",
__func__, cfpkt_getlen(pkt));
return -EOVERFLOW;
}
cfpkt_add_head(pkt, &zero, 1);
/* Add info for MUX-layer to route the packet out. */
info = cfpkt_info(pkt);

5
net/caif/cfveil.c
View File

@ -84,11 +84,6 @@ static int cfvei_transmit(struct cflayer *layr, struct cfpkt *pkt)
return ret;
caif_assert(layr->dn != NULL);
caif_assert(layr->dn->transmit != NULL);
if (cfpkt_getlen(pkt) > CAIF_MAX_PAYLOAD_SIZE) {
pr_warning("CAIF: %s(): Packet too large - size=%d\n",
__func__, cfpkt_getlen(pkt));
return -EOVERFLOW;
}
if (cfpkt_add_head(pkt, &tmp, 1) < 0) {
pr_err("CAIF: %s(): Packet is erroneous!\n", __func__);

67
net/caif/chnl_net.c
View File

@ -23,7 +23,7 @@
#include <net/caif/caif_dev.h>
/* GPRS PDP connection has MTU to 1500 */
#define SIZE_MTU 1500
#define GPRS_PDP_MTU 1500
/* 5 sec. connect timeout */
#define CONNECT_TIMEOUT (5 * HZ)
#define CAIF_NET_DEFAULT_QUEUE_LEN 500
@ -232,6 +232,8 @@ static int chnl_net_open(struct net_device *dev)
{
struct chnl_net *priv = NULL;
int result = -1;
int llifindex, headroom, tailroom, mtu;
struct net_device *lldev;
ASSERT_RTNL();
priv = netdev_priv(dev);
if (!priv) {
@ -241,41 +243,88 @@ static int chnl_net_open(struct net_device *dev)
if (priv->state != CAIF_CONNECTING) {
priv->state = CAIF_CONNECTING;
result = caif_connect_client(&priv->conn_req, &priv->chnl);
result = caif_connect_client(&priv->conn_req, &priv->chnl,
&llifindex, &headroom, &tailroom);
if (result != 0) {
priv->state = CAIF_DISCONNECTED;
pr_debug("CAIF: %s(): err: "
"Unable to register and open device,"
" Err:%d\n",
__func__,
result);
return result;
goto error;
}
lldev = dev_get_by_index(dev_net(dev), llifindex);
if (lldev == NULL) {
pr_debug("CAIF: %s(): no interface?\n", __func__);
result = -ENODEV;
goto error;
}
dev->needed_tailroom = tailroom + lldev->needed_tailroom;
dev->hard_header_len = headroom + lldev->hard_header_len +
lldev->needed_tailroom;
/*
* MTU, head-room etc is not know before we have a
* CAIF link layer device available. MTU calculation may
* override initial RTNL configuration.
* MTU is minimum of current mtu, link layer mtu pluss
* CAIF head and tail, and PDP GPRS contexts max MTU.
*/
mtu = min_t(int, dev->mtu, lldev->mtu - (headroom + tailroom));
mtu = min_t(int, GPRS_PDP_MTU, mtu);
dev_set_mtu(dev, mtu);
dev_put(lldev);
if (mtu < 100) {
pr_warning("CAIF: %s(): "
"CAIF Interface MTU too small (%d)\n",
__func__, mtu);
result = -ENODEV;
goto error;
}
}
rtnl_unlock(); /* Release RTNL lock during connect wait */
result = wait_event_interruptible_timeout(priv->netmgmt_wq,
priv->state != CAIF_CONNECTING,
CONNECT_TIMEOUT);
rtnl_lock();
if (result == -ERESTARTSYS) {
pr_debug("CAIF: %s(): wait_event_interruptible"
" woken by a signal\n", __func__);
return -ERESTARTSYS;
result = -ERESTARTSYS;
goto error;
}
if (result == 0) {
pr_debug("CAIF: %s(): connect timeout\n", __func__);
caif_disconnect_client(&priv->chnl);
priv->state = CAIF_DISCONNECTED;
pr_debug("CAIF: %s(): state disconnected\n", __func__);
return -ETIMEDOUT;
result = -ETIMEDOUT;
goto error;
}
if (priv->state != CAIF_CONNECTED) {
pr_debug("CAIF: %s(): connect failed\n", __func__);
return -ECONNREFUSED;
result = -ECONNREFUSED;
goto error;
}
pr_debug("CAIF: %s(): CAIF Netdevice connected\n", __func__);
return 0;
error:
caif_disconnect_client(&priv->chnl);
priv->state = CAIF_DISCONNECTED;
pr_debug("CAIF: %s(): state disconnected\n", __func__);
return result;
}
static int chnl_net_stop(struct net_device *dev)
@ -321,9 +370,7 @@ static void ipcaif_net_setup(struct net_device *dev)
dev->destructor = free_netdev;
dev->flags |= IFF_NOARP;
dev->flags |= IFF_POINTOPOINT;
dev->needed_headroom = CAIF_NEEDED_HEADROOM;
dev->needed_tailroom = CAIF_NEEDED_TAILROOM;
dev->mtu = SIZE_MTU;
dev->mtu = GPRS_PDP_MTU;
dev->tx_queue_len = CAIF_NET_DEFAULT_QUEUE_LEN;
priv = netdev_priv(dev);