Re: [Libusb-devel] Patch: libusb/os/linux_usbfs.c: Distingush between usbfs and other kernel mode drivers

[Xiaofan C. <xia...@gm...>]

On Wed, Oct 6, 2010 at 12:06 AM, Uwe Bonnes
<bo...@el...> wrote:
> for FTDI devices, in most cases ftdi_sio is loaded. To talk to the device
> via libusb/libftdi, the kernel mode driver needs to be unloaded. However
> this defeats exclusive access, as a second open on the device will now see
> "usbfs" as the kernel mode driver and the same mechanism that unloaded
> ftdi_sio will happily "unload" "usbfs" and give access to the second open().
> Appended patch checks now for "usbfs" driver string and returns another
> value in that case. Higher levels may now check the return value and refrain
> to call libusb_detach_kernel_driver() and so provide excusive access inside
> usbfs/libusb.

For the benefits of others, this patch is the result of the discussion here.
http://developer.intra2net.com/mailarchive/html/libftdi/2010/msg00618.html

Also here.
http://libusb.6.n5.nabble.com/How-to-establish-EXCLUSIVE-instead-of-SHARED-access-to-usb-device-td6878.html

I just wonder why "usbfs" is returned as the kernel driver. Probably
that should be fixed (in the kernel or in libusb).

-- 
Xiaofan