accept在inet层执行inet_accept
(1)调用传输层的接口获得sock{}结构变量
(2)将sock{}与socket{}进行绑定
(3)设置socket{}状态为SS_CONNECTED
int inet_accept(struct socket *sock, struct socket *newsock, int flags)
{
struct sock *sk1 = sock->sk;
int err = -EINVAL;
//调用传输层的具体连接连接过程对于TCP为tcp_prot{}->inet_csk_accept
struct sock *sk2 = sk1->sk_prot->accept(sk1, flags, &err);
if (!sk2)
goto do_err;
//lock_sock()对sk2加锁 设置sk->sk_lock.owned=1
lock_sock(sk2);
//若sk2的状态为一下状态,则警告
WARN_ON(!((1 << sk2->sk_state) &
(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_CLOSE)));
//将sk2和newsock进行绑定
sock_graft(sk2, newsock);
//设置套接字的连接状态为以连接
newsock->state = SS_CONNECTED;
err = 0;
//对sk2解锁设置sk-> sk_lock.owned=0,处理sk_backlog队列上的报文
//sk_backlog队列的作用就是,锁定时报文临时存放在此,解锁时,报文移到sk_receive_queue队列
release_sock(sk2);
do_err:
return err;
}
static inline void sock_graft(struct sock *sk, struct socket *parent)
{
write_lock_bh(&sk->sk_callback_lock);//对sock{}操作进行加锁,写者获取读写锁,并禁止本地软中断
/*
sock的等待队列,在TCP需要等待时就sleep在这个队列上
当进程要求的操作一时无法满足的时候 就在该队列上睡眠等待
*/
sk->sk_sleep = &parent->wait;
parent->sk = sk;//将通信用的socket{}->sk指向新得到的sock{}
sk_set_socket(sk, parent);//将sock{}->sk_socket 指向通信用的socket{}
security_sock_graft(sk, parent);//LSM框架 安全相关的内容
write_unlock_bh(&sk->sk_callback_lock);//对sock{}操作进行解锁 使能本地软中断
}
static inline void sk_set_socket(struct sock *sk, struct socket *sock)
{
sk->sk_socket = sock;
}