From: kaf24@firebug.cl.cam.ac.uk <kaf24@firebug.cl.cam.ac.uk>
Date: Mon, 3 Jul 2006 07:57:15 +0000 (+0100)
Subject: [NET] back: Fix off-by-one error in netbk_tx_err
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15908
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=3de1ac2405d668a2ade90c20ae44a37ea1c66fac;p=xen.git

[NET] back: Fix off-by-one error in netbk_tx_err

The generalised extra request info patch introduced a bug with the use
of netbk_tx_err since it advanced the req_cons pointer by one.  This
patch fixes thing by delaying the increment in netbk_tx_err.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
index 93e39612bc..5171d0ab02 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
@@ -496,9 +496,9 @@ static void netbk_tx_err(netif_t *netif, netif_tx_request_t *txp, RING_IDX end)
 
 	do {
 		make_tx_response(netif, txp, NETIF_RSP_ERROR);
-		if (++cons >= end)
+		if (cons >= end)
 			break;
-		txp = RING_GET_REQUEST(&netif->tx, cons);
+		txp = RING_GET_REQUEST(&netif->tx, cons++);
 	} while (1);
 	netif->tx.req_cons = cons;
 	netif_schedule_work(netif);
@@ -764,11 +764,11 @@ static void net_tx_action(unsigned long unused)
 		if (txreq.flags & NETTXF_extra_info) {
 			work_to_do = netbk_get_extras(netif, extras,
 						      work_to_do);
+			i = netif->tx.req_cons;
 			if (unlikely(work_to_do < 0)) {
-				netbk_tx_err(netif, &txreq, 0);
+				netbk_tx_err(netif, &txreq, i);
 				continue;
 			}
-			i = netif->tx.req_cons;
 		}
 
 		ret = netbk_count_requests(netif, &txreq, work_to_do);