[PATCH] [48/139] tcp: Bug fix in initialization of receive window.

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

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

From: Nandita Dukkipati <nanditad@xxxxxxxxxx>

[ Upstream commit b1afde60f2b9ee8444fba4e012dc99a3b28d224d ]

The bug has to do with boundary checks on the initial receive window.
If the initial receive window falls between init_cwnd and the
receive window specified by the user, the initial window is incorrectly
brought down to init_cwnd. The correct behavior is to allow it to
remain unchanged.

Signed-off-by: Nandita Dukkipati <nanditad@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 net/ipv4/tcp_output.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Index: linux-2.6.35.y/net/ipv4/tcp_output.c
===================================================================
--- linux-2.6.35.y.orig/net/ipv4/tcp_output.c
+++ linux-2.6.35.y/net/ipv4/tcp_output.c
@@ -237,11 +237,10 @@ void tcp_select_initial_window(int __spa
 		/* when initializing use the value from init_rcv_wnd
 		 * rather than the default from above
 		 */
-		if (init_rcv_wnd &&
-		    (*rcv_wnd > init_rcv_wnd * mss))
-			*rcv_wnd = init_rcv_wnd * mss;
-		else if (*rcv_wnd > init_cwnd * mss)
-			*rcv_wnd = init_cwnd * mss;
+		if (init_rcv_wnd)
+			*rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss);
+		else
+			*rcv_wnd = min(*rcv_wnd, init_cwnd * mss);
 	}
 
 	/* Set the clamp no higher than max representable value */
--
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