usbip: Implement a match function to fix usbip
authorM. Vefa Bicakci <m.v.b@runbox.com>
Mon, 10 Aug 2020 16:00:17 +0000 (19:00 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 18 Aug 2020 09:55:23 +0000 (11:55 +0200)
commit7a2f2974f26542b4e7b9b4321edb3cbbf3eeb91a
tree3519987cafb5478e8d07c19b66f2a914e65792a3
parentd66a57be2f9a315fc10d0f524f670fec903e0fb4
usbip: Implement a match function to fix usbip

Commit 88b7381a939d ("USB: Select better matching USB drivers when
available") introduced the use of a "match" function to select a
non-generic/better driver for a particular USB device. This
unfortunately breaks the operation of usbip in general, as reported in
the kernel bugzilla with bug 208267 (linked below).

Upon inspecting the aforementioned commit, one can observe that the
original code in the usb_device_match function used to return 1
unconditionally, but the aforementioned commit makes the usb_device_match
function use identifier tables and "match" virtual functions, if either of
them are available.

Hence, this commit implements a match function for usbip that
unconditionally returns true to ensure that usbip is functional again.

This change has been verified to restore usbip functionality, with a
v5.7.y kernel on an up-to-date version of Qubes OS 4.0, which uses
usbip to redirect USB devices between VMs.

Thanks to Jonathan Dieter for the effort in bisecting this issue down
to the aforementioned commit.

Fixes: 88b7381a939d ("USB: Select better matching USB drivers when available")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=208267
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1856443
Link: https://github.com/QubesOS/qubes-issues/issues/5905
Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
Cc: <stable@vger.kernel.org> # 5.7
Cc: Valentina Manea <valentina.manea.m@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Bastien Nocera <hadess@hadess.net>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200810160017.46002-1-m.v.b@runbox.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/usbip/stub_dev.c