[PATCH 2/3] hyperv: Add a function to detect if the device is a vmbus dev

[kys@exchange.microsoft.com]

From: Haiyang Zhang <haiyangz@microsoft.com>

On Hyper-V, every VF interface has a corresponding synthetic
interface managed by netvsc that share the same MAC
address. netvsc registers for netdev events to manage this
association. Currently we use the MAC address to manage this
association but going forward, we want to use a serial number that
the host publishes. To do this we need functionality similar
to dev_is_pci() for the vmbus devices. Implement such a function.

This function will be used in subsequent patches to netvsc and in the
interest of eliminating cross tree dependencies, this patch is being
submitted first.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/vmbus_drv.c |    6 ++++++
 include/linux/hyperv.h |    2 ++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 230c62e..64c40f3 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -845,6 +845,12 @@ struct onmessage_work_context {
 	struct hv_message msg;
 };
 
+bool dev_is_vmbus(struct device *dev)
+{
+	return dev->bus == &hv_bus;
+}
+EXPORT_SYMBOL_GPL(dev_is_vmbus);
+
 static void vmbus_onmessage_work(struct work_struct *work)
 {
 	struct onmessage_work_context *ctx;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index ff6cd3e..2abb1bf 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -947,6 +947,8 @@ static inline void clear_low_latency_mode(struct vmbus_channel *c)
 	c->low_latency = false;
 }
 
+bool dev_is_vmbus(struct device *dev);
+
 void vmbus_onmessage(void *context);
 
 int vmbus_request_offers(void);
-- 
1.7.4.1