Re: [PATCH 003/117] Staging: hv: Add struct hv_vmbus_device_id to mod_devicetable.h

On Wed, Aug 24, 2011 at 12:44:38AM +0000, KY Srinivasan wrote:

quoted

-----Original Message-----
From: Greg KH [mailto:greg@kroah.com]
Sent: Tuesday, August 23, 2011 6:42 PM
To: KY Srinivasan
Cc: gregkh@suse.de; linux-kernel@vger.kernel.org;
devel@linuxdriverproject.org; virtualization@lists.osdl.org; Haiyang Zhang
Subject: Re: [PATCH 003/117] Staging: hv: Add struct hv_vmbus_device_id to
mod_devicetable.h

On Fri, Jul 15, 2011 at 10:45:51AM -0700, K. Y. Srinivasan wrote:

quoted

In preparation for implementing vmbus aliases for auto-loading
Hyper-V drivers, define vmbus specific device ID.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 include/linux/mod_devicetable.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/linux/mod_devicetable.h

b/include/linux/mod_devicetable.h

quoted

index ae28e93..5a12377 100644

--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h

@@ -405,6 +405,13 @@ struct virtio_device_id {
 };
 #define VIRTIO_DEV_ANY_ID	0xffffffff

+/*
+ * For Hyper-V devices we use the device guid as the id.
+ */
+struct hv_vmbus_device_id {
+	__u8 guid[16];
+};

Why do you not need a driver_data pointer here?  Are you sure you aren't
ever going to need it in the future?  Hint, I think you will...

I am not sure I am following you here; the guid is the device ID and it is 
guaranteed to remain the same. What is the driver _data pointer here 
you are referring to here.  While some device id have the _data pointer,
there are others that don't - for instance struct virtio_device_id. In 
our case, I am not sure how I would use this private pointer.

You use it like all other drivers use it, only if needed.

Hint, I think you need to use it in your hv_utils driver, it would
reduce the size of your code and simplify your logic.

And yes, not all bus types use it, but most do, for good reason.

greg k-h