> -----Original Message----- > From: Greg KH [mailto:gregkh@xxxxxxx] > Sent: Sunday, April 24, 2011 8:14 PM > To: KY Srinivasan > Cc: Greg KH; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > virtualization@xxxxxxxxxxxxxx > Subject: Re: Hyper-V vmbus driver > > On Sun, Apr 24, 2011 at 04:18:24PM +0000, KY Srinivasan wrote: > > > On Mon, Apr 11, 2011 at 12:07:08PM -0700, Greg KH wrote: > > > > > > Due to other external issues, my patch backlog is still not gotten > > > through yet, sorry. Sometimes "real life" intrudes on the best of > > > plans. > > > > > > I'll get to this when I get through the rest of your hv patches, and the > > > other patches pending that I have in my queues. > > > > Thanks Greg. The latest re-send of my hv patches are against the tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6.git > > that I picked up on April 22, 2011. I hope there won't be any issues > > this time around. > > Me too :) Just curious; when are you planning to drain the hv patch queue next. > > > > But, I would recommend you going through and looking at the code and > > > verifying that you feel the bus code is "ready". At a very quick > > > glance, you should not have individual drivers have to set their 'struct > > > device' pointers directly, that is something that the bus does, not the > > > driver. The driver core will call your bus and your bus will then do > > > the matching and call the probe function of the driver if needed. > > > > Are you referring to the fact that in the vmbus_match function, > > the current code binds the device specific driver to the > > corresponding hv_device structure? > > Yes, that's the problem (well, kind of the problem.) > > You seem to be doing things a bit "odd" and that's due to the old way > the code was written. > > First off, don't embed a struct bus_type in another structure, that's > not needed at all. Why is that done? Anyway... Currently, struct bus_type is embedded in struct hv_bus that has very minimal additional state. I will clean this up. > > In your vmbus_match function, you should be matching to see if your > device matches the driver that is passed to you. You do this by looking > at some type of "id". For the vmbus you should do this by looking at > the GUID, right? And it looks like you do do this, so that's fine. > > And then your vmbus_probe() function calls the driver probe function, > with the device it is to bind to. BUT, you need to have your probe > function pass in the correct device type (i.e. struct hv_device, NOT > struct device.) I will clean this up. > > That way, your hv_driver will have a type all its own, with probe > functions that look nothing like the probe functions that 'struct > driver' has in it. Look at 'struct pci_driver' for an example of this. > Don't try to overload the probe/remove/suspend/etc functions of your > hv_driver by using the "base" 'struct device_driver' callbacks, that's > putting knowledge of the driver core into the individual hv drivers, > where it's not needed at all. > > And, by doing that, you should be able to drop your private pointer in > the hv_driver function completly, right? That shouldn't be needed at > all. After sending you the mail this afternoon, I worked on patches that do exactly that. I did this with the current model where probe/remove/ etc. get a pointer to struct device. Within a specific driver you can always map a struct device pointer to the class specific device driver. I will keep that code; I will however do what you are suggesting here and make probe/remove etc. take a pointer to struct hv_device. > > > > See the PCI driver structure for an example of this if you are curious. > > > It should also allow you to get rid of that unneeded *priv pointer in > > > the struct hv_driver. > > > > I am pretty sure, I can get rid of this. The way this code was originally > > structured, in the vmbus_match() function, you needed to get at the > > device specific driver pointer so that we could do the binding between > > the hv_device and the correspond device specific driver. The earlier code > > depended on the structure layout to map a pointer to the hv_driver to > > the corresponding device specific driver (net, block etc.) To get rid of > > this layout dependency, I introduced an addition field (priv) in the hv_driver. > > > > There is, I suspect sufficient state available to: > > > > (a) Not require the vmbus_match() function to do the binding. > > No, you still want that, see above. The current code has the following assignment after a match is found: device_ctx->drv = drv->priv; What I meant was that I would get rid of this assignment (binding) since I can get that information quite easily in the class specific (net, block, etc.) where it is needed. > > > (b) And to get at the device specific driver structure from the generic > > driver structure without having to have an explicit mapping > > maintained in the hv_driver structure. > > Kind of, see above for more details. > > If you want a good example, again, look at the PCI core code, it's > pretty simple in this area (hint, don't look at the USB code, it does > much more complex things than you want, due to things that the USB bus > imposes on devices, that's never a good example to look at.) > > Hope this helps. Please let me know if it doesn't :) Thanks for this detailed mail Greg. As I am writing this email, I have pretty much completed the code for much of what we have discussed here. These are on top of my patches that are yet to be applied (the ones that I sent on April 22). Since some of these changes also affect netvsc code and Haiyang had sent some patches to deal with forward declarations in the netvsc code, I have locally applied haiyang's patches. I will send you these patches soon. Regards, K. Y > > thanks, > > greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
