From: Simon Wilkinson <sxw@your-file-system.com>
Date: Fri, 26 Oct 2012 13:55:02 +0000 (+0100)
Subject: rx: Remove duplicate out of order ACK check
X-Git-Tag: openafs-stable-1_8_0pre1~1861
X-Git-Url: https://git.openafs.org/?p=openafs.git;a=commitdiff_plain;h=8d359e6dff5317698597e77f0a1dd5ba2bfb569a

rx: Remove duplicate out of order ACK check

Once we've moved the congestion window, there's no going back. So
any ACK packets that attempt to move the window backwards by including
a 'firstPacket' value earlier than the current window position must
be ignored.

However, we check (and ignore) these packets twice. Once in
rxi_ReceivePacket, which only checks in the client side case, and again
in rxi_ReceiveAckPacket, which has a more complete check that runs for
both client and server connections.

Remove the identical check from rxi_ReceivePacket in a continuing effort
to clean up this bit of code.

Change-Id: I090bc289848d0797860f46aec5877ad07fcc9b82
Reviewed-on: http://gerrit.openafs.org/8299
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
---

diff --git a/src/rx/rx.c b/src/rx/rx.c
index bfb73fa..0ec9cc8 100644
--- a/src/rx/rx.c
+++ b/src/rx/rx.c
@@ -3569,30 +3569,7 @@ rxi_ReceivePacket(struct rx_packet *np, osi_socket socket,
 #else /* RX_ENABLE_LOCKS */
 	    rxi_ClearTransmitQueue(call, 0);
 #endif /* RX_ENABLE_LOCKS */
-	} else {
-	    if (np->header.type == RX_PACKET_TYPE_ACK) {
-		/* now check to see if this is an ack packet acknowledging that the
-		 * server actually *lost* some hard-acked data.  If this happens we
-		 * ignore this packet, as it may indicate that the server restarted in
-		 * the middle of a call.  It is also possible that this is an old ack
-		 * packet.  We don't abort the connection in this case, because this
-		 * *might* just be an old ack packet.  The right way to detect a server
-		 * restart in the midst of a call is to notice that the server epoch
-		 * changed, btw.  */
-		/* XXX I'm not sure this is exactly right, since tfirst **IS**
-		 * XXX unacknowledged.  I think that this is off-by-one, but
-		 * XXX I don't dare change it just yet, since it will
-		 * XXX interact badly with the server-restart detection
-		 * XXX code in receiveackpacket.  */
-		if (ntohl(rx_GetInt32(np, FIRSTACKOFFSET)) < call->tfirst) {
-                    if (rx_stats_active)
-                        rx_atomic_inc(&rx_stats.spuriousPacketsRead);
-		    MUTEX_EXIT(&call->lock);
-		    putConnection(conn);
-		    return np;
-		}
-	    }
-	}			/* else not a data packet */
+	}
     }
 
     osirx_AssertMine(&call->lock, "rxi_ReceivePacket middle");