[PATCH] Add support for netconsole driver used on bridge device with VIF attached

[Yuval Shaia <yuval.shaia@oracle.com>]

When starting a VM which has virtual interface attached to the same bridge (i.e vif = [type=netfront,bridge=xenbr0'] in vm.cfg) which is used for netconsole the
following message appears (after about 60 seconds) and VM creation operation fails.
     Error: Device 0 (vif) could not be connected. Hotplug scripts not working.

Note:
When trying to do the opposite, i.e. first create VM and then run
netconsole we got the error #524 - vif2.0 doesn't support polling,
aborting.

As i see it, netconsole driver requires ndo_poll_controller from the device's controlling driver (function __netpoll_setup in net/core/netpoll.c), a thing that is not supported currently in xen_netback driver which is the driver that runs on dom0 and serve VM's virtual interface.

The following patch (to latest kernel) fix this bug by adding implementation to ndo_poll_controller.

0001-Add-support-for-netconsole-driver-used-on-bridge-dev.patch
0 2001
From: Yuval <yuval.shaia@oracle.com>
Date: Tue, 8 Jan 2013 10:08:45 +0200
Subject: [PATCH] Add support for netconsole driver used on bridge device with
 VIF attached

Signed-off-by: Yuval <yuval.shaia@oracle.com>
---
 drivers/net/xen-netback/interface.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 601ae2a..10751f5 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -179,6 +179,13 @@ static u32 xenvif_fix_features(struct net_device *dev, u32 features)
 	return features;
 }
 
+static void xenvif_poll_controller(struct net_device *dev)
+{
+	disable_irq(dev->irq);
+	xenvif_interrupt(dev->irq, dev);
+	enable_irq(dev->irq);
+}
+
 static const struct xenvif_stat {
 	char name[ETH_GSTRING_LEN];
 	u16 offset;
@@ -237,6 +244,7 @@ static const struct net_device_ops xenvif_netdev_ops = {
 	.ndo_stop	= xenvif_close,
 	.ndo_change_mtu	= xenvif_change_mtu,
 	.ndo_fix_features = xenvif_fix_features,
+	.ndo_poll_controller = xenvif_poll_controller,
 };
 
 struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
-- 
1.7.9.5