ipv4: Add option to get TCP_FASTOPEN to getsockopt()

Hi,

TCP_FASTOPEN option can be set via setsockopt(), but the value cannot be gotten via getsockopt(). This patch adds the option to getsockopt().

Add option to get TCP_FASTOPEN to getsockopt()

---
 net/ipv4/tcp.c | 7 +++++++
 1 file changed, 7 insertions(+)

index 4bd6d52..86186f4 100644
@@ -2916,6 +2916,13 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
 	case TCP_USER_TIMEOUT:
 		val = jiffies_to_msecs(icsk->icsk_user_timeout);
 		break;
+
+	case TCP_FASTOPEN:
+		val = icsk->icsk_accept_queue.fastopenq ?
+		    icsk->icsk_accept_queue.fastopenq->max_qlen
+		    : sysctl_tcp_fastopen;
+		break;
+
 	case TCP_TIMESTAMP:
 		val = tcp_time_stamp + tp->tsoffset;
 		break;

--
1.9.0

I have no idea why you keep using sysctl_tcp_fastopen in your patches.

It seems you only want your application to
read /proc/sys/net/ipv4/tcp_fastopen ?

And you don't have CONFIG_PROC_FS maybe, and you add a workaround ?

As already mentioned, even if sysctl_tcp_fastopen is set to one, it does not mean this socket is fastopen enabled.

setsockopt()/getsockopt() for a given key should be symmetrical.

ie :

getsockopt(fd, SOL_TCP, TCP_FASTOPEN, &val, &len); setsockopt(fd, SOL_TCP, TCP_FASTOPEN, &val, sizeof(val));

should be a no operation. Its obviously not the case with your proposal.

Please address Neal concerns, and add in the changelog what is this option supposed to do _exactly_.

hint : max_qlen and sysctl_tcp_fastopen do not have the same units, its like comparing apples and oranges.

Thanks

Please omit the "Hi," at the top of the patch description, so the top of the email can be used directly as a git commit description.

Typo: this should be "Signed-off-by:"

Likewise, please omit the extra descriptive text below the "Signed-off-by:" footer.

(And, of course, please note Eric's remarks as well...)

thanks,
neal