From 5b792e164a3ed9d1e27f9259f7dd5a10262745c0 Mon Sep 17 00:00:00 2001
From: Xiao Wang <jasowang@redhat.com>
Date: Tue, 24 May 2011 08:35:26 -0300
Subject: [PATCH 2/2] e1000: check buffer availability

RH-Author: Xiao Wang <jasowang@redhat.com>
Message-id: <20110524083526.21571.58320.stgit@dhcp-8-149.nay.redhat.com>
Patchwork-id: 25391
O-Subject: [RHEL5.7 V2 PATCH 2/2] e1000: check buffer availability
Bugzilla: 704097
RH-Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
RH-Acked-by: Markus Armbruster <armbru@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=704097
Upstream: manually cherry-picked from 6cdfab2868dd593902e2b7db3ba9f49f2cc03e3f
Test status: Tested in my local machine

Reduce spurious packet drops on RX ring empty
by verifying that we have at least 1 buffer
ahead of the time.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 qemu/hw/e1000.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu/hw/e1000.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/qemu/hw/e1000.c b/qemu/hw/e1000.c
index dc17736..aa2e287 100644
--- a/qemu/hw/e1000.c
+++ b/qemu/hw/e1000.c
@@ -630,7 +630,7 @@ e1000_can_receive(void *opaque)
 {
     E1000State *s = opaque;
 
-    return (s->mac_reg[RCTL] & E1000_RCTL_EN);
+    return (s->mac_reg[RCTL] & E1000_RCTL_EN) && e1000_has_rxbufs(s, 1);
 }
 
 static void
-- 
1.7.3.2