This patch mirrors a patch to the Linux uas kernel driver which I've just
submitted. It looks like the qemu uas struct definitions were taken from
the Linux kernel driver, and have inherited the same mistake.
Besides fixing the response iu struct, the patch also drops the add_info
parameter from the usb_uas_queue_response() function, it is always 0 anyways,
and expressing 3 zero-bytes as a function argument is a bit hard.
Below is the long explanation for this change taken from the kernel commit:
The response iu struct before this patch has a size of 7 bytes, which is weird
since all other iu-s are explictly padded to a multiple of 4 bytes.
Submitting a 7 byte bulk transfer to the status endpoint of a real uasp device
when expecting a response iu results in an USB babble error, as the device
actually sends 8 bytes.
Up on closer reading of the UAS spec:
http://www.t10.org/cgi-bin/ac.pl?t=f&f=uas2r00.pdf
The reason for this becomes clear, the 2 entries in "Table 17 — RESPONSE IU"
are numbered 4 and 6, looking at other iu definitions in the spec, esp.
multi-byte fields, this indicates that the ADDITIONAL RESPONSE INFORMATION
field is not a 2 byte field as one might assume at a first look, but is
a multi-byte field containing 3 bytes.
This also aligns with the SCSI Architecture Model 4 spec, which UAS is based
on which states in paragraph "7.1 Task management function procedure calls"
that the "Additional Response Information" output argument for a Task
management function procedure call is 3 bytes.
Last but not least I've verified this by sending a logical unit reset task
management call with an invalid lun to an actual uasp device, and received
back a response-iu with byte 6 being 0, and byte 7 being 9, which is the
responce code for an invalid iu, which confirms that the response code is
being reported in byte 7 of the response iu rather then in byte 6.
Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
projects / qemu-xen-unstable.git / commit