Hi, Folks:
I got confuse on the Linux kernel study. Can anyone help me out there?
The problem is:
For example:
When I use sento(), this will cause interrupt (0x80), and then
transfer to kernel mode. Under kernel mode, it will call
sys_socketcall(SYS_SENDTO). Following the source, I find that the
sys_sendto will be called. Following is the example,
/*
* Send a datagram to a given address. We move the address into kernel
* space and check the user space data area is readable before invoking
* the protocol.
*/
asmlinkage int sys_sendto(int fd, void * buff, int len, unsigned flags,
struct sockaddr *addr, int addr_len)
{
struct socket *sock;
char address[MAX_SOCK_ADDR];
int err;
struct msghdr msg;
struct iovec iov;
if(len<0)
return -EINVAL;
err=verify_area(VERIFY_READ,buff,len);
if(err)
return err;
if (!(sock = sockfd_lookup(fd, &err)))
return err;
iov.iov_base=buff;
iov.iov_len=len;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov=&iov;
msg.msg_iovlen=1;
msg.msg_control=NULL;
if (addr && addr_len) {
err=move_addr_to_kernel(addr,addr_len,address);
if (err < 0)
{
sockfd_put(sock);
return err;
}
msg.msg_name=address;
msg.msg_namelen=addr_len;
}
/****************************************/
/****************************************/
/*
MY problem is here */
/*****************************************/
err=sock->ops->sendmsg(sock, &msg, len, (sock->file->f_flags &
O_NONBLOCK), flags);
/***** WHat/where is the function sock->ops->sendmsg() definition on the
kernel source tree?
*/
sockfd_put(sock);
return err;
} /* define at net/socket.c ****/
/*************************************
I know that sock->ops is the sturct to define the function point of a lot
of function call; However I can not understand/find the define of
sendmsg().
Can any help me? TIA.
C.L.
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