Re: [PATCH] USB: add usbfs ioctl to retrieve the connection parameters

[Alan Stern]

On Mon, 10 Jun 2019, Dmitry Torokhov wrote:

> Recently usfbs gained availability to retrieve device speed, but there
> is sill no way to determine the bus number or list of ports the device
> is connected to when using usbfs. While this information can be obtained
> from sysfs, not all environments allow sysfs access. In a jailed
> environment a program might be simply given an opened file descriptor to
> usbfs device, and it is really important that all data can be gathered
> from said file descriptor.
> 
> This patch introduces a new ioctl, USBDEVFS_CONNINFO_EX, which return
> extended connection information for the device, including the bus
> number, address, port list and speed. The API allows kernel to extend
> amount of data returned by the ioctl and userspace has an option of
> adjusting the amount of data it is willing to consume. A new capability,
> USBDEVFS_CAP_CONNINFO_EX, is introduced to help userspace in determining
> whether the kernel supports this new ioctl.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>