tcp_recvmsg() in 2.4.4

If there are no packets on sk->recieve_queue, and nothing has been copied to userland yet, it seems to me there is a redundant test of sk->done.

About line 1461 in net/ipv4/tcp.c:

		/* Well, if we have backlog, try to process it now yet. */

		if (copied >= target && sk->backlog.tail == NULL)
			break;

		if (copied) {
			if (sk->err ||
			    sk->state == TCP_CLOSE ||
			    (sk->shutdown & RCV_SHUTDOWN) ||
			    !timeo ||
			    (flags & MSG_PEEK))
				break;
		} else {
			if (sk->done)
				break;

			if (sk->err) {
				copied = sock_error(sk);
				break;
			}

			if (sk->shutdown & RCV_SHUTDOWN)
				break;

			if (sk->state == TCP_CLOSE) {
				if (!sk->done) {
					/* This occurs when user tries to read
					 * from never connected socket.
					 */
					copied = -ENOTCONN;
					break;
				}
				break;
			}

			if (!timeo) {
				copied = -EAGAIN;
				break;
			}
		}

When it get to if(sk->state == TCP_CLOSE), surely sk->done has already been tested (and the socket is locked), so -ENOTCONN could be returned immediately.

Actually I'd really appreciate it if someone could explain the order of tests for sk->done, sk->err, sk->shutdown and sk->state...

--

Cheers,
Eric

----------------------------------------------------

|Eric Barton        Barton Software                |
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----------------------------------------------------

We sleep and drop the lock during these loops, so we need to retest this each time we wake back up.

Most of the error test ordering is specified by POSIX somewhere.

Alan would know better.

Later,
David S. Miller
[email protected]

I ordered them that way to match the list given in the posix 1003.1g draft 6.4 specification.

Hi All !
Just wanted to know whether SIOCGIFCOUNT ioctl is implemented in
linux kernel >= 2.4.0. It gives me EINVAL, I browsed thru the code and concluded that this ioctl is not implemented. Am I correct ???

regards
tom