send packet and local-net

linux-6.2/arch/x86/include/asm/current.h

@@ -11,6 +11,7 @@
 
 struct task_struct;
 
+//存储该 CPU 核心的一些运行时信息
 struct pcpu_hot {
 	union {
 		struct {
@@ -22,6 +23,7 @@ struct pcpu_hot {
 #endif
 			unsigned long		top_of_stack;
 			void			*hardirq_stack_ptr;
+			//存储软中断状态
 			u16			softirq_pending;
 #ifdef CONFIG_X86_64
 			bool			hardirq_stack_inuse;

linux-6.2/arch/x86/include/asm/hardirq.h

@@ -60,6 +60,7 @@ extern u64 arch_irq_stat_cpu(unsigned int cpu);
 extern u64 arch_irq_stat(void);
 #define arch_irq_stat		arch_irq_stat
 
+//x86 用于存储当前CPU的软中断（softirq）状态。
 #define local_softirq_pending_ref       pcpu_hot.softirq_pending
 
 #if IS_ENABLED(CONFIG_KVM_INTEL)

linux-6.2/drivers/net/ethernet/intel/igb/igb_main.c

@@ -1226,8 +1226,8 @@ static int igb_alloc_q_vector(struct igb_adapter *adapter,
 		memset(q_vector, 0, size);
 	}
 	if (!q_vector)
-		return -ENOMEM;
-
+		return -ENOMEM; 
+  
 	/* initialize NAPI */
 	//使用 netif_napi_add 注册 NAPI，并指定 igb_poll 作为网络中断的处理函数。NAPI 是一种机制，用于减少中断频率并提高网络吞吐量。
 	netif_napi_add(adapter->netdev, &q_vector->napi, igb_poll);
@@ -2165,6 +2165,7 @@ int igb_up(struct igb_adapter *adapter)
 		wr32(E1000_CTRL_EXT, reg_data);
 	}
 
+	//启用网卡
 	netif_tx_start_all_queues(adapter->netdev);
 
 	/* start the watchdog. */
@@ -4258,6 +4259,7 @@ int igb_setup_tx_resources(struct igb_ring *tx_ring)
 	struct device *dev = tx_ring->dev;
 	int size;
 
+	//申请igb_tx_buffer数组
 	size = sizeof(struct igb_tx_buffer) * tx_ring->count;
 
 	tx_ring->tx_buffer_info = vmalloc(size);
@@ -6177,6 +6179,7 @@ static inline int igb_maybe_stop_tx(struct igb_ring *tx_ring, const u16 size)
 	return __igb_maybe_stop_tx(tx_ring, size);
 }
 
+//将数据放入缓冲区
 static int igb_tx_map(struct igb_ring *tx_ring,
 		      struct igb_tx_buffer *first,
 		      const u8 hdr_len)
@@ -6191,17 +6194,22 @@ static int igb_tx_map(struct igb_ring *tx_ring,
 	u32 cmd_type = igb_tx_cmd_type(skb, tx_flags);
 	u16 i = tx_ring->next_to_use;
 
+	//获取发送描述符
 	tx_desc = IGB_TX_DESC(tx_ring, i);
 
 	igb_tx_olinfo_status(tx_ring, tx_desc, tx_flags, skb->len - hdr_len);
 
+	//计算头部和数据长度
 	size = skb_headlen(skb);
 	data_len = skb->data_len;
 
+	//将数据映射到 DMA 地址
 	dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
 
 	tx_buffer = first;
 
+
+	//负责处理包含多个片段的 TCP/UDP 数据包 遍历数据包 skb 的所有片段
 	for (frag = &skb_shinfo(skb)->frags[0];; frag++) {
 		if (dma_mapping_error(tx_ring->dev, dma))
 			goto dma_error;
@@ -6245,14 +6253,15 @@ static int igb_tx_map(struct igb_ring *tx_ring,
 
 		size = skb_frag_size(frag);
 		data_len -= size;
-
+		//将当前片段映射到设备的 DMA 地址
 		dma = skb_frag_dma_map(tx_ring->dev, frag, 0,
 				       size, DMA_TO_DEVICE);
 
 		tx_buffer = &tx_ring->tx_buffer_info[i];
 	}
 
 	/* write last descriptor with RS and EOP bits */
+	//设置最后一个描述符
 	cmd_type |= size | IGB_TXD_DCMD;
 	tx_desc->read.cmd_type_len = cpu_to_le32(cmd_type);
 
@@ -6430,6 +6439,7 @@ int igb_xmit_xdp_ring(struct igb_adapter *adapter,
 	return IGB_XDP_CONSUMED;
 }
 
+//igb网卡发送数据
 netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
 				struct igb_ring *tx_ring)
 {
@@ -6457,12 +6467,14 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
 	}
 
 	/* record the location of the first descriptor for this packet */
+	//记录第一个描述符的位置
 	first = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
 	first->type = IGB_TYPE_SKB;
 	first->skb = skb;
 	first->bytecount = skb->len;
 	first->gso_segs = 1;
 
+	//时间戳
 	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
 		struct igb_adapter *adapter = netdev_priv(tx_ring->netdev);
 
@@ -6481,6 +6493,7 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
 		}
 	}
 
+	//vlan
 	if (skb_vlan_tag_present(skb)) {
 		tx_flags |= IGB_TX_FLAGS_VLAN;
 		tx_flags |= (skb_vlan_tag_get(skb) << IGB_TX_FLAGS_VLAN_SHIFT);
@@ -6496,6 +6509,7 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
 	else if (!tso)
 		igb_tx_csum(tx_ring, first);
 
+	//调用 igb_tx_map 函数将数据包映射到硬件发送环的描述符
 	if (igb_tx_map(tx_ring, first, hdr_len))
 		goto cleanup_tx_tstamp;
 
@@ -6529,6 +6543,7 @@ static inline struct igb_ring *igb_tx_queue_mapping(struct igb_adapter *adapter,
 	return adapter->tx_ring[r_idx];
 }
 
+//igb网卡发送
 static netdev_tx_t igb_xmit_frame(struct sk_buff *skb,
 				  struct net_device *netdev)
 {
@@ -8884,6 +8899,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 #if (PAGE_SIZE < 8192)
 	frame_sz = igb_rx_frame_truesize(rx_ring, 0);
 #endif
+	//初始化和准备 XDP 缓冲区
 	xdp_init_buff(&xdp, frame_sz, &rx_ring->xdp_rxq);
 
 	//在一个循环中，处理接收队列中的数据包。每次迭代最多处理 budget 个数据包，直到达到 budget 
@@ -8918,6 +8934,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 		//获取缓冲区的地址
 		pktbuf = page_address(rx_buffer->page) + rx_buffer->page_offset;
 
+		//处理时间戳
 		/* pull rx packet timestamp if available and valid */
 		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
 			int ts_hdr_len;
@@ -8970,7 +8987,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 			rx_buffer->pagecnt_bias++;
 			break;
 		}
-
+		//释放接收缓冲区
 		igb_put_rx_buffer(rx_ring, rx_buffer, rx_buf_pgcnt);
 		cleaned_count++;
 

linux-6.2/drivers/net/loopback.c

@@ -66,6 +66,7 @@ EXPORT_SYMBOL(blackhole_netdev);
 /* The higher levels take care of making this non-reentrant (it's
  * called with bh's disabled).
  */
+//本机网络io的发送
 static netdev_tx_t loopback_xmit(struct sk_buff *skb,
 				 struct net_device *dev)
 {
@@ -76,6 +77,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
 	/* do not fool net_timestamp_check() with various clock bases */
 	skb_clear_tstamp(skb);
 
+	//剥离和源socket的联系
 	skb_orphan(skb);
 
 	/* Before queueing this packet to __netif_rx(),
@@ -86,6 +88,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
 	skb->protocol = eth_type_trans(skb, dev);
 
 	len = skb->len;
+	//调用__netif_rx
 	if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
 		dev_lstats_add(dev, len);
 

linux-6.2/include/linux/init.h

@@ -269,6 +269,7 @@ extern bool initcall_debug;
  *
  * Only for built-in code, not modules.
  */
+//在SMP初始化前执行
 #define early_initcall(fn)		__define_initcall(fn, early)
 
 /*

linux-6.2/include/linux/interrupt.h

@@ -520,6 +520,7 @@ DECLARE_STATIC_KEY_FALSE(force_irqthreads_key);
 
 #ifndef local_softirq_pending
 
+//相应架构没有定义时
 #ifndef local_softirq_pending_ref
 //local_softirq_pending_ref实际上是irq_stat结构中的__softirq_pending，__softirq_pending字段中的每一个bit，对应着某一个软中断，某个bit被置位，说明有相应的软中断等待处理。
 #define local_softirq_pending_ref irq_stat.__softirq_pending

linux-6.2/include/linux/netdevice.h

@@ -3037,6 +3037,7 @@ u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb,
 int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev);
 int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id);
 
+//设备子系统入口函数
 static inline int dev_queue_xmit(struct sk_buff *skb)
 {
 	return __dev_queue_xmit(skb, NULL);
@@ -4867,7 +4868,7 @@ static inline ktime_t netdev_get_tstamp(struct net_device *dev,
 
 	return hwtstamps->hwtstamp;
 }
-
+//网络设备子系统 发送
 static inline netdev_tx_t __netdev_start_xmit(const struct net_device_ops *ops,
 					      struct sk_buff *skb, struct net_device *dev,
 					      bool more)
@@ -4881,13 +4882,15 @@ static inline bool netdev_xmit_more(void)
 	return __this_cpu_read(softnet_data.xmit.more);
 }
 
+//发送数据包
 static inline netdev_tx_t netdev_start_xmit(struct sk_buff *skb, struct net_device *dev,
 					    struct netdev_queue *txq, bool more)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	netdev_tx_t rc;
-
+	//调用
 	rc = __netdev_start_xmit(ops, skb, dev, more);
+	//更新时间戳
 	if (rc == NETDEV_TX_OK)
 		txq_trans_update(txq);
 

linux-6.2/include/linux/skbuff.h

@@ -2095,10 +2095,12 @@ static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
  *	The reference count is not incremented and the reference is therefore
  *	volatile. Use with caution.
  */
+//获取sk_buff_head队列的尾部元素
 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
 {
 	struct sk_buff *skb = READ_ONCE(list_->prev);
 
+	//skb为自己 即队列为空
 	if (skb == (struct sk_buff *)list_)
 		skb = NULL;
 	return skb;

linux-6.2/include/linux/socket.h

@@ -30,9 +30,11 @@ typedef __kernel_sa_family_t	sa_family_t;
 /*
  *	1003.1g requires sa_family_t and that sa_data is char.
  */
-
+//对端地址
 struct sockaddr {
+	//地址族
 	sa_family_t	sa_family;	/* address family, AF_xxx	*/
+	//地址数据
 	union {
 		char sa_data_min[14];		/* Minimum 14 bytes of protocol address	*/
 		DECLARE_FLEX_ARRAY(char, sa_data);
@@ -51,13 +53,14 @@ struct linger {
  *	system, not 4.3. Thus msg_accrights(len) are now missing. They
  *	belong in an obscure libc emulation or the bin.
  */
-
+//消息结构体
 struct msghdr {
 	void		*msg_name;	/* ptr to socket address structure */
 	int		msg_namelen;	/* size of socket address structure */
 
 	int		msg_inq;	/* output, data left in socket */
 
+	//数据信息
 	struct iov_iter	msg_iter;	/* data */
 
 	/*
@@ -166,7 +169,7 @@ static inline struct cmsghdr * cmsg_nxthdr (struct msghdr *__msg, struct cmsghdr
 {
 	return __cmsg_nxthdr(__msg->msg_control, __msg->msg_controllen, __cmsg);
 }
-
+//获取数据长度
 static inline size_t msg_data_left(struct msghdr *msg)
 {
 	return iov_iter_count(&msg->msg_iter);

linux-6.2/include/linux/uaccess.h

@@ -116,6 +116,7 @@ __copy_to_user(void __user *to, const void *from, unsigned long n)
 	return raw_copy_to_user(to, from, n);
 }
 
+//
 #ifdef INLINE_COPY_FROM_USER
 static inline __must_check unsigned long
 _copy_from_user(void *to, const void __user *from, unsigned long n)
@@ -124,6 +125,7 @@ _copy_from_user(void *to, const void __user *from, unsigned long n)
 	might_fault();
 	if (!should_fail_usercopy() && likely(access_ok(from, n))) {
 		instrument_copy_from_user_before(to, from, n);
+		//实际操作
 		res = raw_copy_from_user(to, from, n);
 		instrument_copy_from_user_after(to, from, n, res);
 	}
@@ -154,9 +156,11 @@ extern __must_check unsigned long
 _copy_to_user(void __user *, const void *, unsigned long);
 #endif
 
+//从用户空间拷贝
 static __always_inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
-{
+{	
+	//检查to的空间
 	if (check_copy_size(to, n, false))
 		n = _copy_from_user(to, from, n);
 	return n;

linux-6.2/include/linux/uio.h

@@ -38,6 +38,7 @@ struct iov_iter_state {
 	unsigned long nr_segs;
 };
 
+//数据信息
 struct iov_iter {
 	u8 iter_type;
 	bool nofault;
@@ -49,6 +50,7 @@ struct iov_iter {
 	};
 	size_t count;
 	union {
+		//实际数据
 		const struct iovec *iov;
 		const struct kvec *kvec;
 		const struct bio_vec *bvec;

linux-6.2/include/linux/wait.h

@@ -168,6 +168,7 @@ extern void add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wai
 extern void add_wait_queue_priority(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 extern void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 
+//将wq_entry放入wq_head
 static inline void __add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 {
 	struct list_head *head = &wq_head->head;

linux-6.2/include/net/dst.h

@@ -439,6 +439,7 @@ INDIRECT_CALLABLE_DECLARE(int ip6_output(struct net *, struct sock *,
 INDIRECT_CALLABLE_DECLARE(int ip_output(struct net *, struct sock *,
 					 struct sk_buff *));
 /* Output packet to network from transport.  */
+//出口函数 回调ip_output
 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	return INDIRECT_CALL_INET(skb_dst(skb)->output,

linux-6.2/include/net/ip_fib.h

@@ -306,6 +306,7 @@ static inline struct fib_table *fib_new_table(struct net *net, u32 id)
 	return fib_get_table(net, id);
 }
 
+//查找路由核心函数
 static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
 			     struct fib_result *res, unsigned int flags)
 {
@@ -314,6 +315,7 @@ static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
 
 	rcu_read_lock();
 
+	//查询main路由表
 	tb = fib_get_table(net, RT_TABLE_MAIN);
 	if (tb)
 		err = fib_table_lookup(tb, flp, res, flags | FIB_LOOKUP_NOREF);