On Tue, Aug 26, 2014 at 09:06:17AM -0700, Valentina Manea wrote:
> On Tue, Aug 26, 2014 at 6:12 AM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> > This was promoted out of staging and there wasn't an email to the
> > staging list. Normally I like to go through any remaining questions
> > before the code is moved. The code looks pretty good, I just had one
> > question.
> >
>
> I didn't know I should send to that list as well; will keep in mind
> for next time.
Yeah, my fault as well, sorry, I just posted the request on the
linux-usb mailing list.
> > drivers/usb/usbip/usbip_common.c:712 usbip_pad_iso()
> > warn: why is zero skipped 'i'
> >
> > drivers/usb/usbip/usbip_common.c
> > 687 void usbip_pad_iso(struct usbip_device *ud, struct urb *urb)
> > 688 {
> > 689 int np = urb->number_of_packets;
> > 690 int i;
> > 691 int actualoffset = urb->actual_length;
> > 692
> > 693 if (!usb_pipeisoc(urb->pipe))
> > 694 return;
> > 695
> > 696 /* if no packets or length of data is 0, then nothing to unpack */
> > 697 if (np == 0 || urb->actual_length == 0)
> > 698 return;
> > 699
> > 700 /*
> > 701 * if actual_length is transfer_buffer_length then no padding is
> > 702 * present.
> > 703 */
> > 704 if (urb->actual_length == urb->transfer_buffer_length)
> > 705 return;
> > 706
> > 707 /*
> > 708 * loop over all packets from last to first (to prevent overwritting
> > 709 * memory when padding) and move them into the proper place
> > 710 */
> > 711 for (i = np-1; i > 0; i--) {
> >
> > I don't understand this loop. If we really intended to skip the first
> > packet then why isn't the "if (np == 0" condition "if (np <= 1"? That
> > would be more clear and the comment would say "if 1 packet then nothing
> > to unpack."
> >
> > 712 actualoffset -= urb->iso_frame_desc[i].actual_length;
> > 713 memmove(urb->transfer_buffer + urb->iso_frame_desc[i].offset,
> > 714 urb->transfer_buffer + actualoffset,
> > 715 urb->iso_frame_desc[i].actual_length);
> > 716 }
> > 717 }
> >
>
> urb->actual_length is the sum of individual packets' lengths,
> urb->iso_frame_desc[i].actual_length. Since actualoffset in the loop
> keeps decreasing, it will reach 0 when the first packet is processed.
> The first packet's offset is 0 as well and this just does memmove to
> the same buffer location.
> The (np == 0) condition is *not* the same as (np <= 1) because we want
> to return only is there are any packets.
> In my opinion, the code is correct as it is. Do you think I should add
> an extra comment about the loop?
>
> > Also there is a smatch warning:
> > drivers/usb/usbip/stub_tx.c:186 stub_send_ret_submit() warn: returning -1 instead of -ENOMEM is sloppy
> >
>
> Noted, will fix after the patch series is upstream.
You can send the patches now, no need to wait for me as your patches are
already in my tree.
thanks,
greg k-h
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