On 09/09/2011 01:53 PM, Artem Bityutskiy wrote: > On Thu, 2011-09-08 at 17:26 +0200, Arnd Bergmann wrote: >> On Tuesday 06 September 2011, Artem Bityutskiy wrote: >>> Not sure about the bus approach - David, could you take a look at it >>> please? If we can handle errors there - then we could indeed re-use the >>> UBI control device. We could even re-use the ioctl data structures for >>> UBI volumes creation/removal - we have plenty of space there reserved >>> for future extensions. >> @Arnd: > * Use the existing UBI control device for the block devices as > well and just add two more ioctls to create the devices. > You can add a logical bus_type for this so that the ubi block > driver gets automatically loaded matched with the device when > one is created using the control device. I certainly miss some background, I'm not sure I understand how this works: bus_type seems suitable for pluggable devices that possess a device ID which matches against a driver that will then get loaded. But ubiblk devices are created by ubiblk. So, are you suggesting to move ubiblk_create() to UBI and add a MODULE_ALIAS to ubiblk (actually, I don't know what it would contain) ? (I just saw that you sent an email while I was writing this one ; however, I still understand. I'll try and read how scsi does that). @Artem: > Sorry, I wonted to talk about situations when someone opens an ubiblk > device while the underlying UBI volume is being removed, but then though > this is trivial and forgot to erase the last sentence. Ah, yes, I guess we need to hold a vol_lock in ubiblk_remove() ? > Anyway, I suggest the following algorithm: > > 1. Stick with the own cdev approach - the driver becomes very simple > in this case - we review it. This is the way it's implemented in v4, right ? BTW, those are the changes made so far since v4: * Add missing headers (they are included by other headers but it seems to be good practice not to rely on that). * Remove an macro rendered useless with the linked lists * correct some formatting in kerneldoc comments * introduce refcounting to avoid multiple opens or closing a UBI volume while still in use * make checkpatch happy about assignation inside a condition * use DEFINE_MUTEX for devlist_lock Best Regards, David -- David Wagner, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
