File 0008-e1000-check-buffer-availability.patch of Package xen

From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Sun, 27 Mar 2011 13:37:35 +0200
Subject: e1000: check buffer availability
Patch-mainline: v0.15.0-rc0
Git-commit: 6cdfab2868dd593902e2b7db3ba9f49f2cc03e3f
References: bnc#840196

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>
Acked-by: Michal Kubecek <mkubecek@suse.cz>
---
 tools/qemu-xen-traditional-dir-remote/hw/e1000.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/tools/qemu-xen-traditional-dir-remote/hw/e1000.c b/tools/qemu-xen-traditional-dir-remote/hw/e1000.c
index 18d7597..b07c6cb 100644
--- a/tools/qemu-xen-traditional-dir-remote/hw/e1000.c
+++ b/tools/qemu-xen-traditional-dir-remote/hw/e1000.c
@@ -614,14 +614,6 @@ e1000_set_link_status(VLANClientState *vc)
         set_ics(s, 0, E1000_ICR_LSC);
 }
 
-static int
-e1000_can_receive(void *opaque)
-{
-    E1000State *s = opaque;
-
-    return (s->mac_reg[RCTL] & E1000_RCTL_EN && s->mac_reg[RDLEN] != 0);
-}
-
 static bool e1000_has_rxbufs(E1000State *s, size_t total_size)
 {
     int bufs;
@@ -640,6 +632,15 @@ static bool e1000_has_rxbufs(E1000State *s, size_t total_size)
     return total_size <= bufs * s->rxbuf_size;
 }
 
+static int
+e1000_can_receive(void *opaque)
+{
+    E1000State *s = opaque;
+
+    return (s->mac_reg[RCTL] & E1000_RCTL_EN) && (s->mac_reg[RDLEN] != 0) &&
+           e1000_has_rxbufs(s, 1);
+}
+
 static void
 e1000_receive(void *opaque, const uint8_t *buf, int size)
 {
-- 
1.8.1.4