On Fri, 14 Feb 2025 08:41:57 +0100 Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, Feb 14, 2025 at 12:35:44PM +0530, Naman Jain wrote: > > > > > > On 2/14/2025 12:21 PM, Greg Kroah-Hartman wrote: > > > On Fri, Feb 14, 2025 at 12:13:51PM +0530, Naman Jain wrote: > > > > On regular bootup, devices get registered to vmbus first, so when > > > > uio_hv_generic driver for a particular device type is probed, > > > > the device is already initialized and added, so sysfs creation in > > > > uio_hv_generic probe works fine. However, when device is removed > > > > and brought back, the channel rescinds and again gets registered > > > > to vmbus. However this time, the uio_hv_generic driver is already > > > > registered to probe for that device and in this case sysfs creation > > > > is tried before the device gets initialized completely. Fix this by > > > > deferring sysfs creation till device gets initialized completely. > > > > > > > > Problem path: > > > > vmbus_device_register > > > > device_register > > > > uio_hv_generic probe > > > > sysfs_create_bin_file (fails here) > > > > > > Ick, that's the issue, you shouldn't be manually creating sysfs files. > > > Have the driver core do it for you at the proper time, which should make > > > your logic much simpler, right? > > > > > > Set the default attribute groups instead of manually creating this and > > > see if that works out better. > > > > > > thanks, > > > > > > greg k-h > > > > Thanks for reviewing Greg. I tried this approach and here are my > > observations: > > > > What I could create with ATTRIBUTE_GROUPS: > > /sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/ring > > > > The one we have right now: > > /sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/channels/6/ring > > What is "channels" and "6" here? Are they real devices or just a > directory name or something else? > > > I could not find a way to tweak attributes to create the "ring" under above > > path. I could see the variations of sys_create_* which provides a > > way to pass kobj and do that, but that is something we are already > > using. > > No driver should EVER be pointing to a raw kobject, that's a huge hint > that something is really wrong. Also, if a raw kobject is in a device > path in the middle like this, it will not be seen properly from > userspace library tools :( > > So again, what is creating the "channels" and "6" subdirectories? All > of that shoudl be under full control by the uio device, right? The original design of exposing channels was based on what the network core does to expose queues. Worth comparing the two to see if there is any shared insight.
