[Qemu-devel] e1000, virtio_net: Check link status in can_receive

["Yan Vugenfirer" <yvugenfi@redhat.com>]

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Hello,

Fixing the bug of 100% cpu usage by qemu after using "set_link <NIC> down"
monitor command. The fix is for virtio_net and for e1000 emulations.


Best regards,
Yan Vugenfirer.


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>From d5d7ca2cb68e76cd89a17768f6e854b38e7f1efa Mon Sep 17 00:00:00 2001
From: Yan Vugenfirer <yvugenfi@redhat.com>
Date: Sun, 5 Apr 2009 10:21:29 -0400
Subject: [PATCH 0/1] e1000, virtio_net: Check link status in 
can_receive

Fixing the bug of 100% cpu usage by qemu after using "set_link <NIC> 
down"
monitor command. The fix is for virtio_net and for e1000 emulations. 

Yan Vugenfirer (1):
  Fixing the bug of 100% cpu usage by qemu after using "set_link <NIC>
    down" monitor command. The fix is for virtio_net and for e1000
    emulations.

 hw/e1000.c      |    3 ++-
 hw/virtio-net.c |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)


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>From d5d7ca2cb68e76cd89a17768f6e854b38e7f1efa Mon Sep 17 00:00:00 2001
From: Yan Vugenfirer <yvugenfi@redhat.com>
Date: Sun, 5 Apr 2009 10:20:53 -0400
Subject: [PATCH 1/1] e1000, virtio_net: Check link status in can_receive

Fixing the bug of 100% cpu usage by qemu after using "set_link <NIC> down" 
monitor command. The fix is for virtio_net and for e1000 emulations.

---
 hw/e1000.c      |    3 ++-
 hw/virtio-net.c |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/e1000.c b/hw/e1000.c
index 1644201..36878d9 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -590,7 +590,8 @@ e1000_can_receive(void *opaque)
 {
     E1000State *s = opaque;
 
-    return (s->mac_reg[RCTL] & E1000_RCTL_EN);
+    return (s->mac_reg[RCTL] & E1000_RCTL_EN) &&
+           (s->mac_reg[STATUS] & E1000_STATUS_LU);
 }
 
 static void
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index ad55bb7..dcd18c1 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -259,7 +259,8 @@ static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq)
 static int do_virtio_net_can_receive(VirtIONet *n, int bufsize)
 {
     if (!virtio_queue_ready(n->rx_vq) ||
-        !(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
+        !(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
+        !(n->status & VIRTIO_NET_S_LINK_UP))
         return 0;
 
     if (virtio_queue_empty(n->rx_vq) ||
-- 
1.5.5.6