14.1 网络设备驱动结构
- 网络协议接口层：硬件无关，标准收发函数dev_queue_xmit()和netif_rx(); 注意，netif_rx是将接收到的数据给上层，有时也在驱动收到数据以后调用。
- 网络设备接口层，net_device，统一接口名称，使上层独立于具体硬件。
- 设备驱动功能层，实现net_device的各成员
- 物理层
在整个以太网架构里，有两个数据结构非常重要，即sk_buff和net_device，后面两节有说明。
还有一些与内核交互的函数，需要掌握，如netif_start_queue()，netif_stop_queue()，netif_wakeup_queue()，netif_rx()，netif_carrier_on/off_ok()
14.1.1 sk_buff
以太网各层之间用sk_buff结构体传递数据，该结构体是很多函数的形参。
#include <linux/skbuff.h>
/**
* struct sk_buff - socket buffer
* @next: Next buffer in list
* @prev: Previous buffer in list
* @tstamp: Time we arrived
* @sk: Socket we are owned by
* @dev: Device we arrived on/are leaving by
* @cb: Control buffer. Free for use by every layer. Put private vars here
* @_skb_refdst: destination entry (with norefcount bit)
* @sp: the security path, used for xfrm
* @len: Length of actual data
* @data_len: Data length
* @mac_len: Length of link layer header
* @hdr_len: writable header length of cloned skb
* @csum: Checksum (must include start/offset pair)
* @csum_start: Offset from skb->head where checksumming should start
* @csum_offset: Offset from csum_start where checksum should be stored
* @priority: Packet queueing priority
* @local_df: allow local fragmentation
* @cloned: Head may be cloned (check refcnt to be sure)
* @ip_summed: Driver fed us an IP checksum
* @nohdr: Payload reference only, must not modify header
* @nfctinfo: Relationship of this skb to the connection
* @pkt_type: Packet class
* @fclone: skbuff clone status
* @ipvs_property: skbuff is owned by ipvs
* @peeked: this packet has been seen already, so stats have been
* done for it, don't do them again
* @nf_trace: netfilter packet trace flag
* @protocol: Packet protocol from driver
* @destructor: Destruct function
* @nfct: Associated connection, if any
* @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
* @skb_iif: ifindex of device we arrived on
* @tc_index: Traffic control index
* @tc_verd: traffic control verdict
* @rxhash: the packet hash computed on receive
* @queue_mapping: Queue mapping for multiqueue devices
* @ndisc_nodetype: router type (from link layer)
* @ooo_okay: allow the mapping of a socket to a queue to be changed
* @l4_rxhash: indicate rxhash is a canonical 4-tuple hash over transport
* ports.
* @wifi_acked_valid: wifi_acked was set
* @wifi_acked: whether frame was acked on wifi or not
* @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
* @dma_cookie: a cookie to one of several possible DMA operations
* done by skb DMA functions
* @napi_id: id of the NAPI struct this skb came from
* @secmark: security marking
* @mark: Generic packet mark
* @dropcount: total number of sk_receive_queue overflows
* @vlan_proto: vlan encapsulation protocol
* @vlan_tci: vlan tag control information
* @inner_protocol: Protocol (encapsulation)
* @inner_transport_header: Inner transport layer header (encapsulation)
* @inner_network_header: Network layer header (encapsulation)
* @inner_mac_header: Link layer header (encapsulation)
* @transport_header: Transport layer header
* @network_header: Network layer header
* @mac_header: Link layer header
* @tail: Tail pointer
* @end: End pointer
* @head: Head of buffer
* @data: Data head pointer
* @truesize: Buffer size
* @users: User count - see {datagram,tcp}.c
*/
struct sk_buff {
/* These two members must be first. */
struct sk_buff *next;
struct sk_buff *prev;
ktime_t tstamp;
struct sock *sk;
struct net_device *dev;
/*
* This is the control buffer. It is free to use for every
* layer. Please put your private variables there. If you
* want to keep them across layers you have to do a skb_clone()
* first. This is owned by whoever has the skb queued ATM.
*/
char cb[48] __aligned(8);
unsigned long _skb_refdst;
#ifdef CONFIG_XFRM
struct sec_path *sp;
#endif
unsigned int len, // data段的长度
data_len;
__u16 mac_len,
hdr_len;
union {
__wsum csum;
struct {
__u16 csum_start;
__u16 csum_offset;
};
};
__u32 priority;
kmemcheck_bitfield_begin(flags1);
__u8 local_df:1,
cloned:1,
ip_summed:2,
nohdr:1,
nfctinfo:3;
__u8 pkt_type:3,
fclone:2,
ipvs_property:1,
peeked:1,
nf_trace:1;
kmemcheck_bitfield_end(flags1);
__be16 protocol;
void (*destructor)(struct sk_buff *skb);
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
struct nf_conntrack *nfct;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info *nf_bridge;
#endif
int skb_iif;
__u32 rxhash;
__be16 vlan_proto;
__u16 vlan_tci;
#ifdef CONFIG_NET_SCHED
__u16 tc_index; /* traffic control index */
#ifdef CONFIG_NET_CLS_ACT
__u16 tc_verd; /* traffic control verdict */
#endif
#endif
__u16 queue_mapping;
kmemcheck_bitfield_begin(flags2);
#ifdef CONFIG_IPV6_NDISC_NODETYPE
__u8 ndisc_nodetype:2;
#endif
__u8 pfmemalloc:1;
__u8 ooo_okay:1;
__u8 l4_rxhash:1;
__u8 wifi_acked_valid:1;
__u8 wifi_acked:1;
__u8 no_fcs:1;
__u8 head_frag:1;
/* Encapsulation protocol and NIC drivers should use
* this flag to indicate to each other if the skb contains
* encapsulated packet or not and maybe use the inner packet
* headers if needed
*/
__u8 encapsulation:1;
/* 6/8 bit hole (depending on ndisc_nodetype presence) */
kmemcheck_bitfield_end(flags2);
#if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
union {
unsigned int napi_id;
dma_cookie_t dma_cookie;
};
#endif
#ifdef CONFIG_NETWORK_SECMARK
__u32 secmark;
#endif
union {
__u32 mark;
__u32 dropcount;
__u32 reserved_tailroom;
};
__be16 inner_protocol;
__u16 inner_transport_header;
__u16 inner_network_header;
__u16 inner_mac_header;
__u16 transport_header;
__u16 network_header;
__u16 mac_header;
/* These elements must be at the end, see alloc_skb() for details. */
sk_buff_data_t tail;
sk_buff_data_t end;
unsigned char *head,
*data;
unsigned int truesize;
atomic_t users;
};
- 接收时，各层去掉自己的协议，把数据给上层；
- 发送时，各层添加自己的协议，最终给物理网口。
- 上图指针可以动态调整，下面是若干函数
/** tail后移，即在data中增加数据
* skb_put - add data to a buffer
* @skb: buffer to use
* @len: amount of data to add
*
* This function extends the used data area of the buffer. If this would
* exceed the total buffer size the kernel will panic. A pointer to the
* first byte of the extra data is returned.
*/
unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
{
unsigned char *tmp = skb_tail_pointer(skb);
SKB_LINEAR_ASSERT(skb);
skb->tail += len;
skb->len += len;
if (unlikely(skb->tail > skb->end))
skb_over_panic(skb, len, __builtin_return_address(0));
return tmp;
}
/**
* skb_push - add data to the start of a buffer，data前移
* @skb: buffer to use
* @len: amount of data to add
*
* This function extends the used data area of the buffer at the buffer
* start. If this would exceed the total buffer headroom the kernel will
* panic. A pointer to the first byte of the extra data is returned.
*/
unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
{
skb->data -= len;
skb->len += len;
if (unlikely(skb->data<skb->head))
skb_under_panic(skb, len, __builtin_return_address(0));
return skb->data;
}
/**
* skb_pull - remove data from the start of a buffer，data后移
* @skb: buffer to use
* @len: amount of data to remove
*
* This function removes data from the start of a buffer, returning
* the memory to the headroom. A pointer to the next data in the buffer
* is returned. Once the data has been pulled future pushes will overwrite
* the old data.
*/
unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
{
return skb_pull_inline(skb, len);
}
static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
{
return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
}
static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
{
skb->len -= len;
BUG_ON(skb->len < skb->data_len);
return skb->data += len;
}
/**
* skb_reserve - adjust headroom
* @skb: buffer to alter
* @len: bytes to move
*
* Increase the headroom of an empty &sk_buff by reducing the tail
* room. This is only allowed for an empty buffer.
*/
static inline void skb_reserve(struct sk_buff *skb, int len)
{
skb->data += len;
skb->tail += len;
}
// 例子：
skb=alloc_skb(len+headspace, GFP_KERNEL); // 分配
skb_reserve(skb, headspace); // tail=data=起始位置+headspace
skb_put(skb,len); // tail += len
memcpy_fromfs(skb->data,data,len);
pass_to_m_protocol(skb);
sk_buff的动态分配和释放
static inline struct sk_buff *alloc_skb(unsigned int size,
gfp_t priority);/* legacy helper around netdev_alloc_skb() */
static inline struct sk_buff *dev_alloc_skb(unsigned int length);void kfree_skb(struct sk_buff *skb);
void dev_kfree_skb)(struct sk_buff * skb);
/*
* It is not allowed to call kfree_skb() or consume_skb() from hardware
* interrupt context or with hardware interrupts being disabled.
* (in_irq() || irqs_disabled())
*
* We provide four helpers that can be used in following contexts :
*
* dev_kfree_skb_irq(skb) when caller drops a packet from irq context,
* replacing kfree_skb(skb)
*
* dev_consume_skb_irq(skb) when caller consumes a packet from irq context.
* Typically used in place of consume_skb(skb) in TX completion path
*
* dev_kfree_skb_any(skb) when caller doesn't know its current irq context,
* replacing kfree_skb(skb)
*
* dev_consume_skb_any(skb) when caller doesn't know its current irq context,
* and consumed a packet. Used in place of consume_skb(skb)
*/
static inline void dev_kfree_skb_irq(struct sk_buff *skb);
static inline void dev_kfree_skb_any(struct sk_buff *skb);
14.1.2 net_device
net_device有点类似字符设备中的file_opretions,里面定义了很多标准成员函数，驱动需要实现里面的函数。
/*
* The DEVICE structure.
* Actually, this whole structure is a big mistake. It mixes I/O
* data with strictly "high-level" data, and it has to know about
* almost every data structure used in the INET module.
*
* FIXME: cleanup struct net_device such that network protocol info
* moves out.
*/
struct net_device {
/*
* This is the first field of the "visible" part of this structure
* (i.e. as seen by users in the "Space.c" file). It is the name
* of the interface.
*/
char name[IFNAMSIZ]; /* device name hash chain, please keep it close to name[] */
struct hlist_node name_hlist;
/* snmp alias */
char *ifalias;
/*
* I/O specific fields
* FIXME: Merge these and struct ifmap into one
*/
unsigned long mem_end; /* shared mem end */
unsigned long mem_start; /* shared mem start */
unsigned long base_addr; /* device I/O address */
int irq; /* device IRQ number */
/*
* Some hardware also needs these fields, but they are not
* part of the usual set specified in Space.c.
*/
unsigned long state;
struct list_head dev_list;
struct list_head napi_list;
struct list_head unreg_list;
struct list_head close_list;
/* directly linked devices, like slaves for bonding */
struct {
struct list_head upper;
struct list_head lower;
} adj_list;
/* all linked devices, *including* neighbours */
struct {
struct list_head upper;
struct list_head lower;
} all_adj_list;
/* currently active device features */
netdev_features_t features;
/* user-changeable features */
netdev_features_t hw_features;
/* user-requested features */
netdev_features_t wanted_features;
/* mask of features inheritable by VLAN devices */
netdev_features_t vlan_features;
/* mask of features inherited by encapsulating devices
* This field indicates what encapsulation offloads
* the hardware is capable of doing, and drivers will
* need to set them appropriately.
*/
netdev_features_t hw_enc_features;
/* mask of fetures inheritable by MPLS */
netdev_features_t mpls_features;
/* Interface index. Unique device identifier */
int ifindex;
int iflink;
struct net_device_stats stats; // 各种统计信息
atomic_long_t rx_dropped; /* dropped packets by core network
* Do not use this in drivers.
*/
#ifdef CONFIG_WIRELESS_EXT
/* List of functions to handle Wireless Extensions (instead of ioctl).
* See <net/iw_handler.h> for details. Jean II */
const struct iw_handler_def * wireless_handlers;
/* Instance data managed by the core of Wireless Extensions. */
struct iw_public_data * wireless_data;
#endif
/* Management operations */
const struct net_device_ops *netdev_ops; // 具体函数，需驱动填充
const struct ethtool_ops *ethtool_ops;
const struct forwarding_accel_ops *fwd_ops;
/* Hardware header description */
const struct header_ops *header_ops;
unsigned int flags; /* interface flags (a la BSD) ,接口标记，以IFF_开头，说明设备接口的能力和特性*/
unsigned int priv_flags; /* Like 'flags' but invisible to userspace.
* See if.h for definitions. */
unsigned short gflags;
unsigned short padded; /* How much padding added by alloc_netdev() */
unsigned char operstate; /* RFC2863 operstate */
unsigned char link_mode; /* mapping policy to operstate */
unsigned char if_port; /* Selectable AUI, TP,..*/
unsigned char dma; /* DMA channel */
unsigned int mtu; /* interface MTU value，最单传输单元 */
unsigned short type; /* interface hardware type，硬件类型 */
unsigned short hard_header_len; /* hardware hdr length，Dmac+Smac+type=14 */
/* extra head- and tailroom the hardware may need, but not in all cases
* can this be guaranteed, especially tailroom. Some cases also use
* LL_MAX_HEADER instead to allocate the skb.
*/
unsigned short needed_headroom;
unsigned short needed_tailroom;
/* Interface address info. */
unsigned char perm_addr[MAX_ADDR_LEN]; /* permanent hw address */
unsigned char addr_assign_type; /* hw address assignment type */
unsigned char addr_len; /* hardware address length */
unsigned short neigh_priv_len;
unsigned short dev_id; /* Used to differentiate devices
* that share the same link
* layer address
*/
spinlock_t addr_list_lock;
struct netdev_hw_addr_list uc; /* Unicast mac addresses */
struct netdev_hw_addr_list mc; /* Multicast mac addresses */
struct netdev_hw_addr_list dev_addrs; /* list of device
* hw addresses
*/
#ifdef CONFIG_SYSFS
struct kset *queues_kset;
#endif
bool uc_promisc;
unsigned int promiscuity;
unsigned int allmulti;
/* Protocol specific pointers */
#if IS_ENABLED(CONFIG_VLAN_8021Q)
struct vlan_info __rcu *vlan_info; /* VLAN info */
#endif
#if IS_ENABLED(CONFIG_NET_DSA)
struct dsa_switch_tree *dsa_ptr; /* dsa specific data */
#endif
#if IS_ENABLED(CONFIG_TIPC)
struct tipc_bearer __rcu *tipc_ptr; /* TIPC specific data */
#endif
void *atalk_ptr; /* AppleTalk link */
struct in_device __rcu *ip_ptr; /* IPv4 specific data */
struct dn_dev __rcu *dn_ptr; /* DECnet specific data */
struct inet6_dev __rcu *ip6_ptr; /* IPv6 specific data */
void *ax25_ptr; /* AX.25 specific data */
struct wireless_dev *ieee80211_ptr; /* IEEE 802.11 specific data,
assign before registering */
/*
* Cache lines mostly used on receive path (including eth_type_trans())
*/
unsigned long last_rx; /* Time of last Rx
* This should not be set in
* drivers, unless really needed,
* because network stack (bonding)
* use it if/when necessary, to
* avoid dirtying this cache line.
*/
/* Interface address info used in eth_type_trans() */
unsigned char *dev_addr; /* hw address, (before bcast
because most packets are
unicast) */
#ifdef CONFIG_SYSFS
struct netdev_rx_queue *_rx;
/* Number of RX queues allocated at register_netdev() time */
unsigned int num_rx_queues;
/* Number of RX queues currently active in device */
unsigned int real_num_rx_queues;
#endif
rx_handler_func_t __rcu *rx_handler;
void __rcu *rx_handler_data;
struct netdev_queue __rcu *ingress_queue;
unsigned char broadcast[MAX_ADDR_LEN]; /* hw bcast add */
/*
* Cache lines mostly used on transmit path
*/
struct netdev_queue *_tx ____cacheline_aligned_in_smp;
/* Number of TX queues allocated at alloc_netdev_mq() time */
unsigned int num_tx_queues;
/* Number of TX queues currently active in device */
unsigned int real_num_tx_queues;
/* root qdisc from userspace point of view */
struct Qdisc *qdisc;
unsigned long tx_queue_len; /* Max frames per queue allowed */
spinlock_t tx_global_lock;
#ifdef CONFIG_XPS
struct xps_dev_maps __rcu *xps_maps;
#endif
#ifdef CONFIG_RFS_ACCEL
/* CPU reverse-mapping for RX completion interrupts, indexed
* by RX queue number. Assigned by driver. This must only be
* set if the ndo_rx_flow_steer operation is defined. */
struct cpu_rmap *rx_cpu_rmap;
#endif
/* These may be needed for future network-power-down code. */
/*
* trans_start here is expensive for high speed devices on SMP,
* please use netdev_queue->trans_start instead.
*/
unsigned long trans_start; /* Time (in jiffies) of last Tx */
int watchdog_timeo; /* used by dev_watchdog() */
struct timer_list watchdog_timer;
/* Number of references to this device */
int __percpu *pcpu_refcnt;
/* delayed register/unregister */
struct list_head todo_list;
/* device index hash chain */
struct hlist_node index_hlist;
struct list_head link_watch_list;
/* register/unregister state machine */
enum { NETREG_UNINITIALIZED=0,
NETREG_REGISTERED, /* completed register_netdevice */
NETREG_UNREGISTERING, /* called unregister_netdevice */
NETREG_UNREGISTERED, /* completed unregister todo */
NETREG_RELEASED, /* called free_netdev */
NETREG_DUMMY, /* dummy device for NAPI poll */
} reg_state:8;
bool dismantle; /* device is going do be freed */
enum {
RTNL_LINK_INITIALIZED,
RTNL_LINK_INITIALIZING,
} rtnl_link_state:16;
/* Called from unregister, can be used to call free_netdev */
void (*destructor)(struct net_device *dev);
#ifdef CONFIG_NETPOLL
struct netpoll_info __rcu *npinfo;
#endif
#ifdef CONFIG_NET_NS
/* Network namespace this network device is inside */
struct net *nd_net;
#endif
/* mid-layer private */
union {
void *ml_priv;
struct pcpu_lstats __percpu *lstats; /* loopback stats */
struct pcpu_sw_netstats __percpu *tstats;
struct pcpu_dstats __percpu *dstats; /* dummy stats */
struct pcpu_vstats __percpu *vstats; /* veth stats */
};
/* GARP */
struct garp_port __rcu *garp_port;
/* MRP */
struct mrp_port __rcu *mrp_port;
/* class/net/name entry */
struct device dev;
/* space for optional device, statistics, and wireless sysfs groups */
const struct attribute_group *sysfs_groups[4];
/* space for optional per-rx queue attributes */
const struct attribute_group *sysfs_rx_queue_group;
/* rtnetlink link ops */
const struct rtnl_link_ops *rtnl_link_ops;
/* for setting kernel sock attribute on TCP connection setup */
#define GSO_MAX_SIZE 65536
unsigned int gso_max_size;
#define GSO_MAX_SEGS 65535
u16 gso_max_segs;
#ifdef CONFIG_DCB
/* Data Center Bridging netlink ops */
const struct dcbnl_rtnl_ops *dcbnl_ops;
#endif
u8 num_tc;
struct netdev_tc_txq tc_to_txq[TC_MAX_QUEUE];
u8 prio_tc_map[TC_BITMASK + 1];
#if IS_ENABLED(CONFIG_FCOE)
/* max exchange id for FCoE LRO by ddp */
unsigned int fcoe_ddp_xid;
#endif
#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
struct netprio_map __rcu *priomap;
#endif
/* phy device may attach itself for hardware timestamping */
struct phy_device *phydev;
struct lock_class_key *qdisc_tx_busylock;
/* group the device belongs to */
int group;
struct pm_qos_request pm_qos_req;
};
* Standard interface flags (netdevice->flags). */
#defineIFF_UP0x1/* interface is up*/
#defineIFF_BROADCAST0x2/* broadcast address valid*/
#defineIFF_DEBUG0x4/* turn on debugging*/
#defineIFF_LOOPBACK0x8/* is a loopback net*/
#defineIFF_POINTOPOINT0x10/* interface is has p-p link*/
#defineIFF_NOTRAILERS0x20/* avoid use of trailers*/
#defineIFF_RUNNING0x40/* interface RFC2863 OPER_UP*/
#defineIFF_NOARP0x80/* no ARP protocol*/
#defineIFF_PROMISC0x100/* receive all packets*/
#defineIFF_ALLMULTI0x200/* receive all multicast packets*/
#define IFF_MASTER0x400/* master of a load balancer */
#define IFF_SLAVE0x800/* slave of a load balancer*/
#define IFF_MULTICAST0x1000/* Supports multicast*/
#define IFF_PORTSEL0x2000 /* can set media type*/
#define IFF_AUTOMEDIA0x4000/* auto media select active*/
#define IFF_DYNAMIC0x8000/* dialup device with changing addresses*/
#define IFF_LOWER_UP 0x10000 /* driver signals L1 up */
#define IFF_DORMANT0x20000/* driver signals dormant*/
#define IFF_ECHO 0x40000 /* echo sent packets */
#define IFF_VOLATILE (IFF_LOOPBACK|IFF_POINTOPOINT|IFF_BROADCAST|IFF_ECHO|\
IFF_MASTER|IFF_SLAVE|IFF_RUNNING|IFF_LOWER_UP|IFF_DORMANT)
/* Private (from user) interface flags (netdevice->priv_flags). */
#define IFF_802_1Q_VLAN 0x1 /* 802.1Q VLAN device. */
#define IFF_EBRIDGE0x2/* Ethernet bridging device.*/
#define IFF_SLAVE_INACTIVE0x4/* bonding slave not the curr. active */
#define IFF_MASTER_8023AD0x8/* bonding master, 802.3ad. */
#define IFF_MASTER_ALB0x10/* bonding master, balance-alb.*/
#define IFF_BONDING0x20/* bonding master or slave*/
#define IFF_SLAVE_NEEDARP 0x40/* need ARPs for validation*/
#define IFF_ISATAP0x80/* ISATAP interface (RFC4214)*/
#define IFF_MASTER_ARPMON 0x100/* bonding master, ARP mon in use */
#define IFF_WAN_HDLC0x200/* WAN HDLC device*/
#define IFF_XMIT_DST_RELEASE 0x400/* dev_hard_start_xmit() is allowed to
* release skb->dst
*/
#define IFF_DONT_BRIDGE 0x800/* disallow bridging this ether dev */
#define IFF_DISABLE_NETPOLL0x1000/* disable netpoll at run-time */
#define IFF_MACVLAN_PORT0x2000/* device used as macvlan port */
#define IFF_BRIDGE_PORT0x4000/* device used as bridge port */
#define IFF_OVS_DATAPATH0x8000/* device used as Open vSwitch
* datapath port */
#define IFF_TX_SKB_SHARING0x10000/* The interface supports sharing
* skbs on transmit */
#define IFF_UNICAST_FLT0x20000/* Supports unicast filtering*/
#define IFF_TEAM_PORT0x40000/* device used as team port */
#define IFF_SUPP_NOFCS0x80000/* device supports sending custom FCS */
#define IFF_LIVE_ADDR_CHANGE 0x100000/* device supports hardware address
* change when it's running */
#define IFF_MACVLAN 0x200000/* Macvlan device */
net_device中的一个重要结构体是net_device_ops,驱动需要填充里面的成员。
/*
* This structure defines the management hooks for network devices.
* The following hooks can be defined; unless noted otherwise, they are
* optional and can be filled with a null pointer.
*
* int (*ndo_init)(struct net_device *dev);
* This function is called once when network device is registered.
* The network device can use this to any late stage initializaton
* or semantic validattion. It can fail with an error code which will
* be propogated back to register_netdev
*
* void (*ndo_uninit)(struct net_device *dev);
* This function is called when device is unregistered or when registration
* fails. It is not called if init fails.
*
* int (*ndo_open)(struct net_device *dev);一般在次获取设备需要的IO地址、IRQ、DMA通道等
* This function is called when network device transistions to the up
* state.
*
* int (*ndo_stop)(struct net_device *dev);
* This function is called when network device transistions to the down
* state.
*
* netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb,
* struct net_device *dev);
* Called when a packet needs to be transmitted.
* Must return NETDEV_TX_OK , NETDEV_TX_BUSY.
* (can also return NETDEV_TX_LOCKED iff NETIF_F_LLTX)
* Required can not be NULL. 不能为空，必须实现，启动发送
*
* u16 (*ndo_select_queue)(struct net_device *dev, struct sk_buff *skb,
* void *accel_priv, select_queue_fallback_t fallback);
* Called to decide which queue to when device supports multiple
* transmit queues.
*
* void (*ndo_change_rx_flags)(struct net_device *dev, int flags);
* This function is called to allow device receiver to make
* changes to configuration when multicast or promiscious is enabled.
*
* void (*ndo_set_rx_mode)(struct net_device *dev);
* This function is called device changes address list filtering.
* If driver handles unicast address filtering, it should set
* IFF_UNICAST_FLT to its priv_flags.
*
* int (*ndo_set_mac_address)(struct net_device *dev, void *addr);
* This function is called when the Media Access Control address
* needs to be changed. If this interface is not defined, the
* mac address can not be changed.
*
* int (*ndo_validate_addr)(struct net_device *dev);
* Test if Media Access Control address is valid for the device.
*
* int (*ndo_do_ioctl)(struct net_device *dev, struct ifreq *ifr, int cmd);
* Called when a user request an ioctl which can't be handled by
* the generic interface code. If not defined ioctl's return
* not supported error code.
*
* int (*ndo_set_config)(struct net_device *dev, struct ifmap *map);
* Used to set network devices bus interface parameters. This interface
* is retained for legacy reason, new devices should use the bus
* interface (PCI) for low level management. 配置接口，也可以改变设备IO地址和中断号
*
* int (*ndo_change_mtu)(struct net_device *dev, int new_mtu);
* Called when a user wants to change the Maximum Transfer Unit
* of a device. If not defined, any request to change MTU will
* will return an error.
*
* void (*ndo_tx_timeout)(struct net_device *dev);
* Callback uses when the transmitter has not made any progress
* for dev->watchdog ticks. 发送超时以后调用
*
* struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *dev,
* struct rtnl_link_stats64 *storage);
* struct net_device_stats* (*ndo_get_stats)(struct net_device *dev); 返回的结构体包含若干统计信息
* Called when a user wants to get the network device usage
* statistics. Drivers must do one of the following:
* 1. Define @ndo_get_stats64 to fill in a zero-initialised
* rtnl_link_stats64 structure passed by the caller.
* 2. Define @ndo_get_stats to update a net_device_stats structure
* (which should normally be dev->stats) and return a pointer to
* it. The structure may be changed asynchronously only if each
* field is written atomically.
* 3. Update dev->stats asynchronously and atomically, and define
* neither operation.
*
* int (*ndo_vlan_rx_add_vid)(struct net_device *dev, __be16 proto, u16t vid);
* If device support VLAN filtering this function is called when a
* VLAN id is registered.
*
* int (*ndo_vlan_rx_kill_vid)(struct net_device *dev, unsigned short vid);
* If device support VLAN filtering this function is called when a
* VLAN id is unregistered.
*
* void (*ndo_poll_controller)(struct net_device *dev);
*
* SR-IOV management functions.
* int (*ndo_set_vf_mac)(struct net_device *dev, int vf, u8* mac);
* int (*ndo_set_vf_vlan)(struct net_device *dev, int vf, u16 vlan, u8 qos);
* int (*ndo_set_vf_tx_rate)(struct net_device *dev, int vf, int rate);
* int (*ndo_set_vf_spoofchk)(struct net_device *dev, int vf, bool setting);
* int (*ndo_get_vf_config)(struct net_device *dev,
* int vf, struct ifla_vf_info *ivf);
* int (*ndo_set_vf_link_state)(struct net_device *dev, int vf, int link_state);
* int (*ndo_set_vf_port)(struct net_device *dev, int vf,
* struct nlattr *port[]);
* int (*ndo_get_vf_port)(struct net_device *dev, int vf, struct sk_buff *skb);
* int (*ndo_setup_tc)(struct net_device *dev, u8 tc)
* Called to setup 'tc' number of traffic classes in the net device. This
* is always called from the stack with the rtnl lock held and netif tx
* queues stopped. This allows the netdevice to perform queue management
* safely.
*
* Fiber Channel over Ethernet (FCoE) offload functions.
* int (*ndo_fcoe_enable)(struct net_device *dev);
* Called when the FCoE protocol stack wants to start using LLD for FCoE
* so the underlying device can perform whatever needed configuration or
* initialization to support acceleration of FCoE traffic.
*
* int (*ndo_fcoe_disable)(struct net_device *dev);
* Called when the FCoE protocol stack wants to stop using LLD for FCoE
* so the underlying device can perform whatever needed clean-ups to
* stop supporting acceleration of FCoE traffic.
*
* int (*ndo_fcoe_ddp_setup)(struct net_device *dev, u16 xid,
* struct scatterlist *sgl, unsigned int sgc);
* Called when the FCoE Initiator wants to initialize an I/O that
* is a possible candidate for Direct Data Placement (DDP). The LLD can
* perform necessary setup and returns 1 to indicate the device is set up
* successfully to perform DDP on this I/O, otherwise this returns 0.
*
* int (*ndo_fcoe_ddp_done)(struct net_device *dev, u16 xid);
* Called when the FCoE Initiator/Target is done with the DDPed I/O as
* indicated by the FC exchange id 'xid', so the underlying device can
* clean up and reuse resources for later DDP requests.
*
* int (*ndo_fcoe_ddp_target)(struct net_device *dev, u16 xid,
* struct scatterlist *sgl, unsigned int sgc);
* Called when the FCoE Target wants to initialize an I/O that
* is a possible candidate for Direct Data Placement (DDP). The LLD can
* perform necessary setup and returns 1 to indicate the device is set up
* successfully to perform DDP on this I/O, otherwise this returns 0.
*
* int (*ndo_fcoe_get_hbainfo)(struct net_device *dev,
* struct netdev_fcoe_hbainfo *hbainfo);
* Called when the FCoE Protocol stack wants information on the underlying
* device. This information is utilized by the FCoE protocol stack to
* register attributes with Fiber Channel management service as per the
* FC-GS Fabric Device Management Information(FDMI) specification.
*
* int (*ndo_fcoe_get_wwn)(struct net_device *dev, u64 *wwn, int type);
* Called when the underlying device wants to override default World Wide
* Name (WWN) generation mechanism in FCoE protocol stack to pass its own
* World Wide Port Name (WWPN) or World Wide Node Name (WWNN) to the FCoE
* protocol stack to use.
*
* RFS acceleration.
* int (*ndo_rx_flow_steer)(struct net_device *dev, const struct sk_buff *skb,
* u16 rxq_index, u32 flow_id);
* Set hardware filter for RFS. rxq_index is the target queue index;
* flow_id is a flow ID to be passed to rps_may_expire_flow() later.
* Return the filter ID on success, or a negative error code.
*
* Slave management functions (for bridge, bonding, etc).
* int (*ndo_add_slave)(struct net_device *dev, struct net_device *slave_dev);
* Called to make another netdev an underling.
*
* int (*ndo_del_slave)(struct net_device *dev, struct net_device *slave_dev);
* Called to release previously enslaved netdev.
*
* Feature/offload setting functions.
* netdev_features_t (*ndo_fix_features)(struct net_device *dev,
* netdev_features_t features);
* Adjusts the requested feature flags according to device-specific
* constraints, and returns the resulting flags. Must not modify
* the device state.
*
* int (*ndo_set_features)(struct net_device *dev, netdev_features_t features);
* Called to update device configuration to new features. Passed
* feature set might be less than what was returned by ndo_fix_features()).
* Must return >0 or -errno if it changed dev->features itself.
*
* int (*ndo_fdb_add)(struct ndmsg *ndm, struct nlattr *tb[],
* struct net_device *dev,
* const unsigned char *addr, u16 flags)
* Adds an FDB entry to dev for addr.
* int (*ndo_fdb_del)(struct ndmsg *ndm, struct nlattr *tb[],
* struct net_device *dev,
* const unsigned char *addr)
* Deletes the FDB entry from dev coresponding to addr.
* int (*ndo_fdb_dump)(struct sk_buff *skb, struct netlink_callback *cb,
* struct net_device *dev, int idx)
* Used to add FDB entries to dump requests. Implementers should add
* entries to skb and update idx with the number of entries.
*
* int (*ndo_bridge_setlink)(struct net_device *dev, struct nlmsghdr *nlh)
* int (*ndo_bridge_getlink)(struct sk_buff *skb, u32 pid, u32 seq,
* struct net_device *dev, u32 filter_mask)
*
* int (*ndo_change_carrier)(struct net_device *dev, bool new_carrier);
* Called to change device carrier. Soft-devices (like dummy, team, etc)
* which do not represent real hardware may define this to allow their
* userspace components to manage their virtual carrier state. Devices
* that determine carrier state from physical hardware properties (eg
* network cables) or protocol-dependent mechanisms (eg
* USB_CDC_NOTIFY_NETWORK_CONNECTION) should NOT implement this function.
*
* int (*ndo_get_phys_port_id)(struct net_device *dev,
* struct netdev_phys_port_id *ppid);
* Called to get ID of physical port of this device. If driver does
* not implement this, it is assumed that the hw is not able to have
* multiple net devices on single physical port.
*
* void (*ndo_add_vxlan_port)(struct net_device *dev,
* sa_family_t sa_family, __be16 port);
* Called by vxlan to notiy a driver about the UDP port and socket
* address family that vxlan is listnening to. It is called only when
* a new port starts listening. The operation is protected by the
* vxlan_net->sock_lock.
*
* void (*ndo_del_vxlan_port)(struct net_device *dev,
* sa_family_t sa_family, __be16 port);
* Called by vxlan to notify the driver about a UDP port and socket
* address family that vxlan is not listening to anymore. The operation
* is protected by the vxlan_net->sock_lock.
*
* void* (*ndo_dfwd_add_station)(struct net_device *pdev,
* struct net_device *dev)
* Called by upper layer devices to accelerate switching or other
* station functionality into hardware. 'pdev is the lowerdev
* to use for the offload and 'dev' is the net device that will
* back the offload. Returns a pointer to the private structure
* the upper layer will maintain.
* void (*ndo_dfwd_del_station)(struct net_device *pdev, void *priv)
* Called by upper layer device to delete the station created
* by 'ndo_dfwd_add_station'. 'pdev' is the net device backing
* the station and priv is the structure returned by the add
* operation.
* netdev_tx_t (*ndo_dfwd_start_xmit)(struct sk_buff *skb,
* struct net_device *dev,
* void *priv);
* Callback to use for xmit over the accelerated station. This
* is used in place of ndo_start_xmit on accelerated net
* devices.
*/
struct net_device_ops {
int (*ndo_init)(struct net_device *dev);
void (*ndo_uninit)(struct net_device *dev);
int (*ndo_open)(struct net_device *dev);
int (*ndo_stop)(struct net_device *dev);
netdev_tx_t (*ndo_start_xmit) (struct sk_buff *skb,
struct net_device *dev);
u16 (*ndo_select_queue)(struct net_device *dev,
struct sk_buff *skb,
void *accel_priv,
select_queue_fallback_t fallback);
void (*ndo_change_rx_flags)(struct net_device *dev,
int flags);
void (*ndo_set_rx_mode)(struct net_device *dev);
int (*ndo_set_mac_address)(struct net_device *dev,
void *addr);
int (*ndo_validate_addr)(struct net_device *dev);
int (*ndo_do_ioctl)(struct net_device *dev,
struct ifreq *ifr, int cmd);
int (*ndo_set_config)(struct net_device *dev,
struct ifmap *map);
int (*ndo_change_mtu)(struct net_device *dev,
int new_mtu);
int (*ndo_neigh_setup)(struct net_device *dev,
struct neigh_parms *);
void (*ndo_tx_timeout) (struct net_device *dev);
struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *dev,
struct rtnl_link_stats64 *storage);
struct net_device_stats* (*ndo_get_stats)(struct net_device *dev);
int (*ndo_vlan_rx_add_vid)(struct net_device *dev,
__be16 proto, u16 vid);
int (*ndo_vlan_rx_kill_vid)(struct net_device *dev,
__be16 proto, u16 vid);
#ifdef CONFIG_NET_POLL_CONTROLLER
void (*ndo_poll_controller)(struct net_device *dev);
int (*ndo_netpoll_setup)(struct net_device *dev,
struct netpoll_info *info,
gfp_t gfp);
void (*ndo_netpoll_cleanup)(struct net_device *dev);
#endif
#ifdef CONFIG_NET_RX_BUSY_POLL
int (*ndo_busy_poll)(struct napi_struct *dev);
#endif
int (*ndo_set_vf_mac)(struct net_device *dev,
int queue, u8 *mac);
int (*ndo_set_vf_vlan)(struct net_device *dev,
int queue, u16 vlan, u8 qos);
int (*ndo_set_vf_tx_rate)(struct net_device *dev,
int vf, int rate);
int (*ndo_set_vf_spoofchk)(struct net_device *dev,
int vf, bool setting);
int (*ndo_get_vf_config)(struct net_device *dev,
int vf,
struct ifla_vf_info *ivf);
int (*ndo_set_vf_link_state)(struct net_device *dev,
int vf, int link_state);
int (*ndo_set_vf_port)(struct net_device *dev,
int vf,
struct nlattr *port[]);
int (*ndo_get_vf_port)(struct net_device *dev,
int vf, struct sk_buff *skb);
int (*ndo_setup_tc)(struct net_device *dev, u8 tc);
#if IS_ENABLED(CONFIG_FCOE)
int (*ndo_fcoe_enable)(struct net_device *dev);
int (*ndo_fcoe_disable)(struct net_device *dev);
int (*ndo_fcoe_ddp_setup)(struct net_device *dev,
u16 xid,
struct scatterlist *sgl,
unsigned int sgc);
int (*ndo_fcoe_ddp_done)(struct net_device *dev,
u16 xid);
int (*ndo_fcoe_ddp_target)(struct net_device *dev,
u16 xid,
struct scatterlist *sgl,
unsigned int sgc);
int (*ndo_fcoe_get_hbainfo)(struct net_device *dev,
struct netdev_fcoe_hbainfo *hbainfo);
#endif
#if IS_ENABLED(CONFIG_LIBFCOE)
#define NETDEV_FCOE_WWNN 0
#define NETDEV_FCOE_WWPN 1
int (*ndo_fcoe_get_wwn)(struct net_device *dev,
u64 *wwn, int type);
#endif
#ifdef CONFIG_RFS_ACCEL
int (*ndo_rx_flow_steer)(struct net_device *dev,
const struct sk_buff *skb,
u16 rxq_index,
u32 flow_id);
#endif
int (*ndo_add_slave)(struct net_device *dev,
struct net_device *slave_dev);
int (*ndo_del_slave)(struct net_device *dev,
struct net_device *slave_dev);
netdev_features_t (*ndo_fix_features)(struct net_device *dev,
netdev_features_t features);
int (*ndo_set_features)(struct net_device *dev,
netdev_features_t features);
int (*ndo_neigh_construct)(struct neighbour *n);
void (*ndo_neigh_destroy)(struct neighbour *n);
int (*ndo_fdb_add)(struct ndmsg *ndm,
struct nlattr *tb[],
struct net_device *dev,
const unsigned char *addr,
u16 flags);
int (*ndo_fdb_del)(struct ndmsg *ndm,
struct nlattr *tb[],
struct net_device *dev,
const unsigned char *addr);
int (*ndo_fdb_dump)(struct sk_buff *skb,
struct netlink_callback *cb,
struct net_device *dev,
int idx);
int (*ndo_bridge_setlink)(struct net_device *dev,
struct nlmsghdr *nlh);
int (*ndo_bridge_getlink)(struct sk_buff *skb,
u32 pid, u32 seq,
struct net_device *dev,
u32 filter_mask);
int (*ndo_bridge_dellink)(struct net_device *dev,
struct nlmsghdr *nlh);
int (*ndo_change_carrier)(struct net_device *dev,
bool new_carrier);
int (*ndo_get_phys_port_id)(struct net_device *dev,
struct netdev_phys_port_id *ppid);
void (*ndo_add_vxlan_port)(struct net_device *dev,
sa_family_t sa_family,
__be16 port);
void (*ndo_del_vxlan_port)(struct net_device *dev,
sa_family_t sa_family,
__be16 port);
void* (*ndo_dfwd_add_station)(struct net_device *pdev,
struct net_device *dev);
void (*ndo_dfwd_del_station)(struct net_device *pdev,
void *priv);
netdev_tx_t (*ndo_dfwd_start_xmit) (struct sk_buff *skb,
struct net_device *dev,
void *priv);
};
14.2 注册与注销
14.2.1 注册与注销
register时，net_device的net_device_ops的ndo_init()会执行。
/**
* register_netdev - register a network device
* @dev: device to register
*
* Take a completed network device structure and add it to the kernel
* interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
* chain. 0 is returned on success. A negative errno code is returned
* on a failure to set up the device, or if the name is a duplicate.
*
* This is a wrapper around register_netdevice that takes the rtnl semaphore
* and expands the device name if you passed a format string to
* alloc_netdev.
*/
int register_netdev(struct net_device *dev);
/**
* unregister_netdev - remove device from the kernel
* @dev: device
*
* This function shuts down a device interface and removes it
* from the kernel tables.
*
* This is just a wrapper for unregister_netdevice that takes
* the rtnl semaphore. In general you want to use this and not
* unregister_netdevice.
*/
void unregister_netdev(struct net_device *dev);
14.2.2 申请和释放
可以自己定义net_device结构体，也可以动态申请和释放空间。
// sizeof_priv是自定义数据结构的大小
// setup是动态申请后，自动执行的初始化函数，下面两个ether申请函数，都有默认的setup函数
#define alloc_netdev(sizeof_priv, name, setup) \ alloc_netdev_mqs(sizeof_priv, name, setup, 1, 1)
#define alloc_etherdev(sizeof_priv) alloc_etherdev_mq(sizeof_priv, 1)
#define alloc_etherdev_mq(sizeof_priv, count) alloc_etherdev_mqs(sizeof_priv, count, count)
/**
* alloc_etherdev_mqs - Allocates and sets up an Ethernet device
* @sizeof_priv: Size of additional driver-private structure to be allocated
* for this Ethernet device
* @txqs: The number of TX queues this device has.
* @rxqs: The number of RX queues this device has.
*
* Fill in the fields of the device structure with Ethernet-generic
* values. Basically does everything except registering the device.
*
* Constructs a new net device, complete with a private data area of
* size (sizeof_priv). A 32-byte (not bit) alignment is enforced for
* this private data area.
*/
struct net_device *alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs,
unsigned int rxqs)
{
return alloc_netdev_mqs(sizeof_priv, "eth%d", ether_setup, txqs, rxqs);
}
/**
* alloc_netdev_mqs - allocate network device
* @sizeof_priv: size of private data to allocate space for
* @name: device name format string
* @setup: callback to initialize device
* @txqs: the number of TX subqueues to allocate
* @rxqs: the number of RX subqueues to allocate
*
* Allocates a struct net_device with private data area for driver use
* and performs basic initialization. Also allocates subqueue structs
* for each queue on the device.
*/
struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
void (*setup)(struct net_device *),
unsigned int txqs, unsigned int rxqs)
{
struct net_device *dev;
size_t alloc_size;
struct net_device *p;
BUG_ON(strlen(name) >= sizeof(dev->name));
if (txqs < 1) {
pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
return NULL;
}
#ifdef CONFIG_SYSFS
if (rxqs < 1) {
pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
return NULL;
}
#endif
alloc_size = sizeof(struct net_device);
if (sizeof_priv) {
/* ensure 32-byte alignment of private area */
alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
alloc_size += sizeof_priv;
}
/* ensure 32-byte alignment of whole construct */
alloc_size += NETDEV_ALIGN - 1;
p = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
if (!p)
p = vzalloc(alloc_size);
if (!p)
return NULL;
dev = PTR_ALIGN(p, NETDEV_ALIGN);
dev->padded = (char *)dev - (char *)p;
dev->pcpu_refcnt = alloc_percpu(int);
if (!dev->pcpu_refcnt)
goto free_dev;
if (dev_addr_init(dev))
goto free_pcpu;
dev_mc_init(dev);
dev_uc_init(dev);
dev_net_set(dev, &init_net);
dev->gso_max_size = GSO_MAX_SIZE;
dev->gso_max_segs = GSO_MAX_SEGS;
INIT_LIST_HEAD(&dev->napi_list);
INIT_LIST_HEAD(&dev->unreg_list);
INIT_LIST_HEAD(&dev->close_list);
INIT_LIST_HEAD(&dev->link_watch_list);
INIT_LIST_HEAD(&dev->adj_list.upper);
INIT_LIST_HEAD(&dev->adj_list.lower);
INIT_LIST_HEAD(&dev->all_adj_list.upper);
INIT_LIST_HEAD(&dev->all_adj_list.lower);
dev->priv_flags = IFF_XMIT_DST_RELEASE;
setup(dev);
dev->num_tx_queues = txqs;
dev->real_num_tx_queues = txqs;
if (netif_alloc_netdev_queues(dev))
goto free_all;
#ifdef CONFIG_SYSFS
dev->num_rx_queues = rxqs;
dev->real_num_rx_queues = rxqs;
if (netif_alloc_rx_queues(dev))
goto free_all;
#endif
strcpy(dev->name, name);
dev->group = INIT_NETDEV_GROUP;
if (!dev->ethtool_ops)
dev->ethtool_ops = &default_ethtool_ops;
return dev;
free_all:
free_netdev(dev);
return NULL;
free_pcpu:
free_percpu(dev->pcpu_refcnt);
netif_free_tx_queues(dev);
#ifdef CONFIG_SYSFS
kfree(dev->_rx);
#endif
free_dev:
netdev_freemem(dev);
return NULL;
}
// 释放net_device
void free_netdev(struct net_device *dev);
模板：
static int xxx_register(void)
{
...
/* 分配 net_device 结构体并对其成员赋值 */
xxx_dev = alloc_netdev(sizeof(struct xxx_priv), "sn%d", xxx_init);
if (xxx_dev == NULL)
... /* 分配 net_device 失败 */
/* 注册 net_device 结构体 */
if ((result = register_netdev(xxx_dev)))
...
}
static void xxx_unregister(void)
{
...
/* 注销 net_device 结构体 */
unregister_netdev(xxx_dev);
/* 释放 net_device 结构体 */
free_netdev(xxx_dev);
}
14.3 初始化ndo_init()
向内核register时，ndo_init()函数会被执行。
int register_netdev(struct net_device *dev)
{
int err;
rtnl_lock();
err = register_netdevice(dev);
rtnl_unlock();
return err;
}
int register_netdevice(struct net_device *dev)
{
...
/* Init, if this function is available */
if (dev->netdev_ops->ndo_init) {
ret = dev->netdev_ops->ndo_init(dev);
if (ret) {
if (ret > 0)
ret = -EIO;
goto out;
}
}
...
}
ndo_init()要干的事：
- 准备硬件
- 初始化net_device结构体的相关内容
- 获取私有指针，并初始化
ndo_init()模板：
xxx_netdev_ops.ndo_init = xxx_init;
void xxx_init(struct net_device *dev)
{
/* 设备的私有信息结构体 */
struct xxx_priv *priv;
/* 检查设备是否存在和设备所使用的硬件资源 */
xxx_hw_init();
/* 初始化以太网设备的公用成员 */
ether_setup(dev);
/* 设置设备的成员函数指针 */
ndev->netdev_ops = &xxx_netdev_ops;
ndev->ethtool_ops = &xxx_ethtool_ops;
dev->watchdog_timeo = timeout;
/* 取得私有信息， 并初始化它 */
priv = netdev_priv(dev);
... /* 初始化设备私有数据区 */
}
14.4 打开和释放ndo_open()/ndo_stop()
ndo_open()的工作：
- 使能硬件资源，申请IO区域、中断和DMA通道等；
- 调用netif_start_queue()函数，激活设备发送队列
ndo_stop()的工作：
- 调用netif_stop_queue()函数，停止设备发送队列
- 释放IO区域、中断和DMA资源
原来这两个函数只针对 tx queue
/** * netif_start_queue - allow transmit
* @dev: network device
*
* Allow upper layers to call the device hard_start_xmit routine.
*/
static inline void netif_start_queue(struct net_device *dev)
{
netif_tx_start_queue(netdev_get_tx_queue(dev, 0));
}
/**
* netif_stop_queue - stop transmitted packets
* @dev: network device
*
* Stop upper layers calling the device hard_start_xmit routine.
* Used for flow control when transmit resources are unavailable.
*/
static inline void netif_stop_queue(struct net_device *dev)
{
netif_tx_stop_queue(netdev_get_tx_queue(dev, 0));
}
/**
*netif_wake_queue - restart transmit
*@dev: network device
*
*Allow upper layers to call the device hard_start_xmit routine.
*Used for flow control when transmit resources are available.
*/
static inline void netif_wake_queue(struct net_device *dev)
{
netif_tx_wake_queue(netdev_get_tx_queue(dev, 0));
}
模板：
xxx_netdev_ops.ndo_open = xxx_open;
xxx_netdev_ops.ndo_stop = xxx_stop;
static int xxx_open(struct net_device *dev)
{
/* 申请端口、 IRQ 等， 类似于 fops->open */
ret = request_irq(dev->irq, &xxx_interrupt, 0, dev->name, dev);
...
netif_start_queue(dev);
...
}
static int xxx_stop(struct net_device *dev)
{
/* 释放端口、 IRQ 等， 类似于 fops->close */
free_irq(dev->irq, dev);
...
netif_stop_queue(dev); /* can't transmit any more */
...
}
14.5 发送 ndo_start_xmit()/ndo_tx_timeout()
ndo_start_xmit()主要流程：
- 解析sk_buff，缓存有效数据
- 校验数据长度，若小于ETH_ZLEN（60，不包含FCS），则尾部填充0
- 控制硬件发送数据
int xxx_tx(struct sk_buff *skb, struct net_device *dev)
{
int len;
char *data, shortpkt[ETH_ZLEN];
if (xxx_send_available(...)) { /* 发送队列未满， 可以发送 */
/* 获得有效数据指针和长度 */
data = skb->data;
len = skb->len;
if (len < ETH_ZLEN) {
/* 如果帧长小于以太网帧最小长度， 补 0 */
memset(shortpkt, 0, ETH_ZLEN);
memcpy(shortpkt, skb->data, skb->len);
len = ETH_ZLEN;
data = shortpkt;
}
dev->trans_start = jiffies; /* 记录发送时间戳 */
if (avail) {/* 设置硬件寄存器， 让硬件把数据包发送出去 */
xxx_hw_tx(data, len, dev);
} else {
netif_stop_queue(dev); // 不一定非要这么搞，返回busy也可以，如果调用了，需要在TX结束中断或者超时中断里唤醒
...
}
}
}
void xxx_tx_timeout(struct net_device *dev)
{
...
netif_wake_queue(dev); /* 重新启动设备发送队列 */ }
14.6 接收
没有固定形式，在需要的地方调用netif_rx()即可。
static void xxx_interrupt(int irq, void *dev_id)
{
...
switch (status &ISQ_EVENT_MASK) {
case ISQ_RECEIVER_EVENT:
/* 获取数据包 */
xxx_rx(dev);
break;
/* 其他类型的中断 */
}
}
static void xxx_rx(struct xxx_device *dev)
{
...
length = get_rev_len (...);
/* 分配新的套接字缓冲区 */
skb = dev_alloc_skb(length + 2);
skb_reserve(skb, 2); /* 对齐 */
skb->dev = dev;
/* 读取硬件上接收到的数据 */
insw(ioaddr + RX_FRAME_PORT, skb_put(skb, length), length >> 1);
if (length &1)
skb->data[length - 1] = inw(ioaddr + RX_FRAME_PORT);
/* 获取上层协议类型 */
skb->protocol = eth_type_trans(skb, dev);
/* 把数据包交给上层 */
netif_rx(skb);
/* 记录接收时间戳 */
dev->last_rx = jiffies;
...
}
14.7 连接状态
一般在定时中断里，检查并更新连接状态。
static inline bool netif_carrier_ok(const struct net_device *dev); // 连接是否ok
void netif_carrier_on(struct net_device *dev); // 改变连接状态，on
void netif_carrier_off(struct net_device *dev); // 改变连接状态，off
14.8 参数设置和统计数据
参数设置可以通过ioctl()，传入的描述符为socket，linux对命令做了统一规定，如下：
/*路径： include/uapi/linux/sockios.h */
/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Definitions of the socket-level I/O control calls.
*
* Version: @(#)sockios.h 1.0.2 03/09/93
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _LINUX_SOCKIOS_H
#define _LINUX_SOCKIOS_H
#include <asm/sockios.h>
/* Linux-specific socket ioctls */
#define SIOCINQ FIONREAD
#define SIOCOUTQ TIOCOUTQ /* output queue size (not sent + not acked) */
/* Routing table calls. */
#define SIOCADDRT 0x890B /* add routing table entry */
#define SIOCDELRT 0x890C /* delete routing table entry */
#define SIOCRTMSG 0x890D /* call to routing system */
/* Socket configuration controls. */
#define SIOCGIFNAME 0x8910 /* get iface name */
#define SIOCSIFLINK 0x8911 /* set iface channel */
#define SIOCGIFCONF 0x8912 /* get iface list */
#define SIOCGIFFLAGS 0x8913 /* get flags */
#define SIOCSIFFLAGS 0x8914 /* set flags */
#define SIOCGIFADDR 0x8915 /* get PA address */
#define SIOCSIFADDR 0x8916 /* set PA address */
#define SIOCGIFDSTADDR 0x8917 /* get remote PA address */
#define SIOCSIFDSTADDR 0x8918 /* set remote PA address */
#define SIOCGIFBRDADDR 0x8919 /* get broadcast PA address */
#define SIOCSIFBRDADDR 0x891a /* set broadcast PA address */
#define SIOCGIFNETMASK 0x891b /* get network PA mask */
#define SIOCSIFNETMASK 0x891c /* set network PA mask */
#define SIOCGIFMETRIC 0x891d /* get metric */
#define SIOCSIFMETRIC 0x891e /* set metric */
#define SIOCGIFMEM 0x891f /* get memory address (BSD) */
#define SIOCSIFMEM 0x8920 /* set memory address (BSD) */
#define SIOCGIFMTU 0x8921 /* get MTU size */
#define SIOCSIFMTU 0x8922 /* set MTU size */
#define SIOCSIFNAME 0x8923 /* set interface name */
#define SIOCSIFHWADDR 0x8924 /* set hardware address */
#define SIOCGIFENCAP 0x8925 /* get/set encapsulations */
#define SIOCSIFENCAP 0x8926
#define SIOCGIFHWADDR 0x8927 /* Get hardware address */
#define SIOCGIFSLAVE 0x8929 /* Driver slaving support */
#define SIOCSIFSLAVE 0x8930
#define SIOCADDMULTI 0x8931 /* Multicast address lists */
#define SIOCDELMULTI 0x8932
#define SIOCGIFINDEX 0x8933 /* name -> if_index mapping */
#define SIOGIFINDEX SIOCGIFINDEX /* misprint compatibility :-) */
#define SIOCSIFPFLAGS 0x8934 /* set/get extended flags set */
#define SIOCGIFPFLAGS 0x8935
#define SIOCDIFADDR 0x8936 /* delete PA address */
#define SIOCSIFHWBROADCAST 0x8937 /* set hardware broadcast addr */
#define SIOCGIFCOUNT 0x8938 /* get number of devices */
#define SIOCGIFBR 0x8940 /* Bridging support */
#define SIOCSIFBR 0x8941 /* Set bridging options */
#define SIOCGIFTXQLEN 0x8942 /* Get the tx queue length */
#define SIOCSIFTXQLEN 0x8943 /* Set the tx queue length */
/* SIOCGIFDIVERT was: 0x8944 Frame diversion support */
/* SIOCSIFDIVERT was: 0x8945 Set frame diversion options */
#define SIOCETHTOOL 0x8946 /* Ethtool interface */
#define SIOCGMIIPHY 0x8947 /* Get address of MII PHY in use. */
#define SIOCGMIIREG 0x8948 /* Read MII PHY register. */
#define SIOCSMIIREG 0x8949 /* Write MII PHY register. */
#define SIOCWANDEV 0x894A /* get/set netdev parameters */
#define SIOCOUTQNSD 0x894B /* output queue size (not sent only) */
/* ARP cache control calls. */
/* 0x8950 - 0x8952 * obsolete calls, don't re-use */
#define SIOCDARP 0x8953 /* delete ARP table entry */
#define SIOCGARP 0x8954 /* get ARP table entry */
#define SIOCSARP 0x8955 /* set ARP table entry */
/* RARP cache control calls. */
#define SIOCDRARP 0x8960 /* delete RARP table entry */
#define SIOCGRARP 0x8961 /* get RARP table entry */
#define SIOCSRARP 0x8962 /* set RARP table entry */
/* Driver configuration calls */
#define SIOCGIFMAP 0x8970 /* Get device parameters */
#define SIOCSIFMAP 0x8971 /* Set device parameters */
/* DLCI configuration calls */
#define SIOCADDDLCI 0x8980 /* Create new DLCI device */
#define SIOCDELDLCI 0x8981 /* Delete DLCI device */
#define SIOCGIFVLAN 0x8982 /* 802.1Q VLAN support */
#define SIOCSIFVLAN 0x8983 /* Set 802.1Q VLAN options */
/* bonding calls */
#define SIOCBONDENSLAVE 0x8990 /* enslave a device to the bond */
#define SIOCBONDRELEASE 0x8991 /* release a slave from the bond*/
#define SIOCBONDSETHWADDR 0x8992 /* set the hw addr of the bond */
#define SIOCBONDSLAVEINFOQUERY 0x8993 /* rtn info about slave state */
#define SIOCBONDINFOQUERY 0x8994 /* rtn info about bond state */
#define SIOCBONDCHANGEACTIVE 0x8995 /* update to a new active slave */
/* bridge calls */
#define SIOCBRADDBR 0x89a0 /* create new bridge device */
#define SIOCBRDELBR 0x89a1 /* remove bridge device */
#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
#define SIOCBRDELIF 0x89a3 /* remove interface from bridge */
/* hardware time stamping: parameters in linux/net_tstamp.h */
#define SIOCSHWTSTAMP 0x89b0 /* set and get config */
#define SIOCGHWTSTAMP 0x89b1 /* get config */
/* Device private ioctl calls */
/*
* These 16 ioctls are available to devices via the do_ioctl() device
* vector. Each device should include this file and redefine these names
* as their own. Because these are device dependent it is a good idea
* _NOT_ to issue them to random objects and hope.
*
* THESE IOCTLS ARE _DEPRECATED_ AND WILL DISAPPEAR IN 2.5.X -DaveM
*/
#define SIOCDEVPRIVATE 0x89F0 /* to 89FF */
/*
* These 16 ioctl calls are protocol private
*/
#define SIOCPROTOPRIVATE 0x89E0 /* to 89EF */
#endif /* _LINUX_SOCKIOS_H */
ndo_get_stats()模板，在程序合适的地方对各种计数进行设置即可。
struct net_device_stats *xxx_stats(struct net_device *dev)
{
…
return &dev->stats;
}
struct net_device_stats
{
unsigned long rx_packets; /* 收到的数据包数 */
unsigned long tx_packets; /* 发送的数据包数 */
unsigned long rx_bytes; /* 收到的字节数 */
unsigned long tx_bytes; /* 发送的字节数 */
unsigned long rx_errors; /* 收到的错误数据包数 */
unsigned long tx_errors; /* 发生发送错误的数据包数 */
...
};
14.9 DM9000实例
14.10 总结