Re: [PATCH] usbip: vhci_hcd: move sysfs attribute setup into probe/remove

[Deepanshu Kartikey]

On Sat, Aug 15, 2026 at 9:02 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> If you are going to move the creation, please do so in a race-free way
> and properly make the driver core control this by setting these up as
> default attributes.
>

v2 does this - the group is now registered as dev_groups on the platform
driver, so the core creates the files before probe and removes them after
remove returns.  Both sysfs_create_group() and sysfs_remove_group() are
gone from the driver.

The attributes have only ever been created on vhci_hcd.0, even though the
driver binds to one device per controller, so an is_visible() callback
keeps them there rather than changing what userspace sees.

vhci_init_attr_group() moves into vhci_hcd_init() ahead of
platform_driver_register(), so the group is populated before the core
reads it.


> WHat has recently changed to make this start to fail now to require this
> change?
>

Nothing recent.  The window has been there since 1c9de5bf42861 ("usbip:
vhci-hcd: Add USB3 SuperSpeed support"), which added the second hcd and
left the group creation guarded by usb_hcd_is_primary_hcd().  That means
the attach attribute goes live during the first usb_add_hcd(), before
vhci_hcd_ss is set, and survives the first usb_put_hcd() on removal.


Thanks

Deepanshu