网络设备之分配net_device结构

注册网络设备时，会调用pci_driver->probe函数，以e100为例，最终会调用alloc_netdev_mqs来分配内存，并且在分配内存后调用setup函数(以太网为ether_setup)初始化二层地址等信息，这里主要分析alloc_netdev_mqs函数，以及ether_setup函数：

e100_probe----->alloc_etherdev----->alloc_netdev_mqs

|

|---->ether_setup

  1 /**
  2  * alloc_netdev_mqs - allocate network device
  3  * @sizeof_priv: size of private data to allocate space for
  4  * @name: device name format string
  5  * @name_assign_type: origin of device name
  6  * @setup: callback to initialize device
  7  * @txqs: the number of TX subqueues to allocate
  8  * @rxqs: the number of RX subqueues to allocate
  9  *
 10  * Allocates a struct net_device with private data area for driver use
 11  * and performs basic initialization.  Also allocates subqueue structs
 12  * for each queue on the device.
 13  */
 14 struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 15         unsigned char name_assign_type,
 16         void (*setup)(struct net_device *),
 17         unsigned int txqs, unsigned int rxqs)
 18 {
 19     struct net_device *dev;
 20     size_t alloc_size;
 21     struct net_device *p;
 22
 23     BUG_ON(strlen(name) >= sizeof(dev->name));
 24
 25     /* 检查发送队列数 */
 26     if (txqs < 1) {
 27         pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
 28         return NULL;
 29     }
 30
 31     /* 检查接收队列数 */
 32 #ifdef CONFIG_SYSFS
 33     if (rxqs < 1) {
 34         pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
 35         return NULL;
 36     }
 37 #endif
 38
 39     /* 计算net_device结构大小 */
 40     alloc_size = sizeof(struct net_device);
 41     /* 加上私有数据大小 */
 42     if (sizeof_priv) {
 43         /* ensure 32-byte alignment of private area */
 44         alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
 45         alloc_size += sizeof_priv;
 46     }
 47     /* ensure 32-byte alignment of whole construct */
 48     /* 整个空间做对齐后的大小 */
 49     alloc_size += NETDEV_ALIGN - 1;
 50
 51     /* 分配内存 */
 52     p = kvzalloc(alloc_size, GFP_KERNEL | __GFP_REPEAT);
 53     if (!p)
 54         return NULL;
 55
 56     /* 内存对齐 */
 57     dev = PTR_ALIGN(p, NETDEV_ALIGN);
 58
 59     /* 计算对齐的填充 */
 60     dev->padded = (char *)dev - (char *)p;
 61
 62     /* 分配设备引用 */
 63     dev->pcpu_refcnt = alloc_percpu(int);
 64     if (!dev->pcpu_refcnt)
 65         goto free_dev;
 66
 67     /* 地址列表初始化 */
 68     if (dev_addr_init(dev))
 69         goto free_pcpu;
 70
 71     /* 组播列表初始化 */
 72     dev_mc_init(dev);
 73
 74     /* 单播列表初始化 */
 75     dev_uc_init(dev);
 76
 77     /* 设置net */
 78     dev_net_set(dev, &init_net);
 79
 80     /* GSO设置 */
 81     dev->gso_max_size = GSO_MAX_SIZE;
 82     dev->gso_max_segs = GSO_MAX_SEGS;
 83
 84     /* 初始化各种链表 */
 85     INIT_LIST_HEAD(&dev->napi_list);
 86     INIT_LIST_HEAD(&dev->unreg_list);
 87     INIT_LIST_HEAD(&dev->close_list);
 88     INIT_LIST_HEAD(&dev->link_watch_list);
 89     INIT_LIST_HEAD(&dev->adj_list.upper);
 90     INIT_LIST_HEAD(&dev->adj_list.lower);
 91     INIT_LIST_HEAD(&dev->ptype_all);
 92     INIT_LIST_HEAD(&dev->ptype_specific);
 93 #ifdef CONFIG_NET_SCHED
 94     hash_init(dev->qdisc_hash);
 95 #endif
 96     dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
 97
 98     /* 初始化设备硬件地址，mtu等参数 */
 99     setup(dev);
100
101     /* 队列长度为0，则采用默认值 */
102     if (!dev->tx_queue_len) {
103         dev->priv_flags |= IFF_NO_QUEUE;
104         dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
105     }
106
107     /* 设置发送队列数 */
108     dev->num_tx_queues = txqs;
109     dev->real_num_tx_queues = txqs;
110
111     /* 分配初始化发送队列 */
112     if (netif_alloc_netdev_queues(dev))
113         goto free_all;
114
115 #ifdef CONFIG_SYSFS
116     /* 设置接收队列数 */
117     dev->num_rx_queues = rxqs;
118     dev->real_num_rx_queues = rxqs;
119
120     /* 分配初始化接收队列 */
121     if (netif_alloc_rx_queues(dev))
122         goto free_all;
123 #endif
124
125     /* 拷贝名字 */
126     strcpy(dev->name, name);
127
128     /* 赋值名字赋值类型 */
129     dev->name_assign_type = name_assign_type;
130
131     /* 设置设备组 */
132     dev->group = INIT_NETDEV_GROUP;
133
134     /* 设置默认ethtool操作 */
135     if (!dev->ethtool_ops)
136         dev->ethtool_ops = &default_ethtool_ops;
137
138     /* 初始化netfilter入口 */
139     nf_hook_ingress_init(dev);
140
141     return dev;
142
143 free_all:
144     free_netdev(dev);
145     return NULL;
146
147 free_pcpu:
148     free_percpu(dev->pcpu_refcnt);
149 free_dev:
150     netdev_freemem(dev);
151     return NULL;
152 }

 1 /**
 2  * ether_setup - setup Ethernet network device
 3  * @dev: network device
 4  *
 5  * Fill in the fields of the device structure with Ethernet-generic values.
 6  */
 7 void ether_setup(struct net_device *dev)
 8 {
 9     dev->header_ops        = &eth_header_ops;
10     dev->type        = ARPHRD_ETHER;
11     dev->hard_header_len     = ETH_HLEN;
12     dev->min_header_len    = ETH_HLEN;
13     dev->mtu        = ETH_DATA_LEN;
14     dev->min_mtu        = ETH_MIN_MTU;
15     dev->max_mtu        = ETH_DATA_LEN;
16     dev->addr_len        = ETH_ALEN;
17     dev->tx_queue_len    = DEFAULT_TX_QUEUE_LEN;
18     dev->flags        = IFF_BROADCAST|IFF_MULTICAST;
19     dev->priv_flags        |= IFF_TX_SKB_SHARING;
20
21     eth_broadcast_addr(dev->broadcast);
22
23 }