17.16. Quick Reference
This section provides a
reference for the concepts introduced in this chapter. It also
explains the role of each header file that a driver needs to include.
The lists of fields in the net_device and
sk_buff structures, however, are not repeated
here.- #include <linux/netdevice.h>
Header that hosts the definitions of struct
net_device and struct
net_device_stats, and includes a few other headers
that are needed by network drivers.
- struct net_device *alloc_netdev(int sizeof_priv, char *name, void
- (*setup)(struct net_device *);
- struct net_device *alloc_etherdev(int sizeof_priv);
- void free_netdev(struct net_device *dev);
Functions for allocating and freeing net_device
structures.
- int register_netdev(struct net_device *dev);
- void unregister_netdev(struct net_device *dev);
Registers and unregisters a network device.
- void *netdev_priv(struct net_device *dev);
A function that retrieves the pointer to the driver-private area of a
network device structure.
- struct net_device_stats;
A structure that holds device statistics.
- netif_start_queue(struct net_device *dev);
- netif_stop_queue(struct net_device *dev);
- netif_wake_queue(struct net_device *dev);
Functions that control the passing of packets to the driver for
transmission. No packets are transmitted until
netif_start_queue has been called.
netif_stop_queue suspends transmission, and
netif_wake_queue restarts the queue and pokes
the network layer to restart transmitting packets.
- skb_shinfo(struct sk_buff *skb);
A macro that provides access to the "shared
info" portion of a packet buffer.
- void netif_rx(struct sk_buff *skb);
Function that can be called (including at interrupt time) to notify
the kernel that a packet has been received and encapsulated into a
socket buffer.
- void netif_rx_schedule(dev);
Function that informs the kernel that packets are available and that
polling should be started on the interface; it is used only by
NAPI-compliant drivers.
- int netif_receive_skb(struct sk_buff *skb);
- void netif_rx_complete(struct net_device *dev);
Functions that should be used only by NAPI-compliant drivers.
netif_receive_skb is the NAPI equivalent to
netif_rx; it feeds a packet into the kernel.
When a NAPI-compliant driver has exhausted the supply of received
packets, it should reenable interrupts, and call
netif_rx_complete to stop polling.
- #include <linux/if.h>
Included by netdevice.h, this file declares the
interface flags (IFF_ macros) and struct
ifmap, which has a major role in the
ioctl implementation for network drivers.
- void netif_carrier_off(struct net_device *dev);
- void netif_carrier_on(struct net_device *dev);
- int netif_carrier_ok(struct net_device *dev);
The first two functions may be used to tell the kernel whether a
carrier signal is currently present on the given interface.
netif_carrier_ok tests the carrier state as
reflected in the device structure.
- #include <linux/if_ether.h>
- ETH_ALEN
- ETH_P_IP
- struct ethhdr;
Included by netdevice.h,
if_ether.h defines all the
ETH_ macros used to represent octet lengths (such
as the address length) and network protocols (such as IP). It also
defines the ethhdr structure.
- #include <linux/skbuff.h>
The definition of struct sk_buff and related
structures, as well as several inline functions to act on the
buffers. This header is included by netdevice.h.
- struct sk_buff *alloc_skb(unsigned int len, int priority);
- struct sk_buff *dev_alloc_skb(unsigned int len);
- void kfree_skb(struct sk_buff *skb);
- void dev_kfree_skb(struct sk_buff *skb);
- void dev_kfree_skb_irq(struct sk_buff *skb);
- void dev_kfree_skb_any(struct sk_buff *skb);
Functions that handle the allocation and freeing of socket buffers.
Drivers should normally use the dev_ variants,
which are intended for that purpose.
- unsigned char *skb_put(struct sk_buff *skb, int len);
- unsigned char *_ _skb_put(struct sk_buff *skb, int len);
- unsigned char *skb_push(struct sk_buff *skb, int len);
- unsigned char *_ _skb_push(struct sk_buff *skb, int len);
Functions that add data to an skb;
skb_put puts the data at the end of the
skb, while skb_push puts it
at the beginning. The regular versions perform checking to ensure
that adequate space is available; double-underscore versions leave
those tests out.
- int skb_headroom(struct sk_buff *skb);
- int skb_tailroom(struct sk_buff *skb);
- void skb_reserve(struct sk_buff *skb, int len);
Functions that perform management of space within an
skb. skb_headroom and
skb_tailroom tell how much space is available at
the beginning and end, respectively, of an skb.
skb_reserve may be used to reserve space at the
beginning of an skb, which must be empty.
- unsigned char *skb_pull(struct sk_buff *skb, int len);
skb_pull
"removes" data from an
skb by adjusting the internal pointers.
- int skb_is_nonlinear(struct sk_buff *skb);
Function that returns a true value if this skb is separated into
multiple fragments for scatter/gather I/O.
- int skb_headlen(struct sk_buff *skb);
Returns the length of the first segment of the skbthat part
pointed to by skb->data.
- void *kmap_skb_frag(skb_frag_t *frag);
- void kunmap_skb_frag(void *vaddr);
Functions that provide direct access to fragments within a nonlinear
skb.
- #include <linux/etherdevice.h>
- void ether_setup(struct net_device *dev);
Function that sets most device methods to the general-purpose
implementation for Ethernet drivers. It also sets
dev->flags and assigns the next available
ethx name to dev->name if
the first character in the name is a blank space or the
NULL character.
- unsigned short eth_type_trans(struct sk_buff *skb, struct net_device *dev);
When an Ethernet interface receives a packet, this function can be
called to set skb->pkt_type. The return value
is a protocol number that is usually stored in
skb->protocol.
- #include <linux/sockios.h>
- SIOCDEVPRIVATE
The first of 16 ioctl commands that can be
implemented by each driver for its own private use. All the network
ioctl commands are defined in
sockios.h.
- #include <linux/mii.h>
- struct mii_if_info;
Declarations and a structure supporting drivers of devices that
implement the MII standard.
- #include <linux/ethtool.h>
- struct ethtool_ops;
Declarations and structures that let devices work with the
ethtool utility.
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