Re: Linux 2.6.0-test9

On Sun, 26 Oct 2003 18:10:03 -0800 (PST), Linus Torvalds wrote:

On Mon, 27 Oct 2003 Andries.Brouwer@cwi.nl wrote:

quoted

rlogin followed by "emacs -nw".

Ok. I bet I've never seen it partly because I only use ssh (I don't even
allow rlogin to any of my machines). But you're right, rlogin certainly
not only uses OOB data, but uses SIGURG itself. I would actually expect 
that if we delay the SIGURG until after we've read the URG data, the child 
process that wants to actually read the URG data will trivially hang, 
waiting for it.

If this is easily repeatable for you, can you test just applying this
patch on top of plain -test9? It's not the patch I'd actually do in real 
life, but it's the minimal patch to verify that it's really SIGURG and 
urgent data that is the thing you see. Sounds very likely, but it would be 
good to really verify.

This patch does fix the rlogin + emacs -nw problems.

/Mikael

quoted hunk

--- 1.49/net/ipv4/tcp.c	Mon Oct 20 22:27:42 2003
+++ edited/net/ipv4/tcp.c	Sun Oct 26 17:59:14 2003

@@ -1536,9 +1536,15 @@

		struct sk_buff *skb;
		u32 offset;

-		/* Are we at urgent data? Stop if we have read anything. */
-		if (copied && tp->urg_data && tp->urg_seq == *seq)
-			break;
+		/* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
+		if (tp->urg_data && tp->urg_seq == *seq) {
+			if (copied)
+				break;
+			if (signal_pending(current)) {
+				copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
+				break;
+			}
+		}

		/* Next get a buffer. */