[34-longterm 140/209] tcp: Bug fix in initialization of receive window.

[Paul Gortmaker]

From: Nandita Dukkipati <nanditad@xxxxxxxxxx>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit b1afde60f2b9ee8444fba4e012dc99a3b28d224d upstream

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: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 net/ipv4/tcp_output.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a5cf575..e1819aa 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -237,11 +237,10 @@ void tcp_select_initial_window(int __space, __u32 mss,
 		/* 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 */
-- 
1.7.4.4

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