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SubjectRe: [PATCH v2 0/2] usbip: Implement SG support
On Fri, Jul 19, 2019 at 04:04:20PM -0600, shuah wrote:
> On 7/5/19 10:43 AM, Suwan Kim wrote:
> > There are bugs on vhci with usb 3.0 storage device. Originally, vhci
> > doesn't supported SG, so USB storage driver on vhci breaks SG list
> > into multiple URBs and it causes error that a transfer got terminated
> > too early because the transfer length for one of the URBs was not
> > divisible by the maxpacket size.
> >
> > To support SG, vhci doesn't map and unmap URB for DMA to use native
> > SG list (urb->num_sgs). In DMA mapping function of vhci, it sets
> > URB_DMA_MAP_SG flag in urb->transfer_flags if URB has SG list and
> > this flag will tell the stub driver to use SG list.
> >
> > In this patch, vhci basically support SG and it sends each SG list
> > entry to the stub driver. Then, the stub driver sees the total length
> > of the buffer and allocates SG table and pages according to the total
> > buffer length calling sgl_alloc(). After the stub driver receives
> > completed URB, it again sends each SG list entry to vhci.
> >
> > If HCD of the server doesn't support SG, the stub driver breaks a
> > single SG reqeust into several URBs and submit them to the server's
> > HCD. When all the split URBs are completed, the stub driver
> > reassembles the URBs into a single return command and sends it to
> > vhci.
> >
> > Alan fixed vhci bug with the USB 3.0 storage device by modifying
> > USB storage driver.
> > ("usb-storage: Set virt_boundary_mask to avoid SG overflows")
> > But the fundamental solution of it is to add SG support to vhci.
> >
> > This patch works well with the USB 3.0 storage devices without Alan's
> > patch, and we can revert Alan's patch if it causes some troubles.
> >
> > Suwan Kim (2):
> > usbip: Skip DMA mapping and unmapping for urb at vhci
> > usbip: Implement SG support to vhci
> >
> > drivers/usb/usbip/stub.h | 7 +-
> > drivers/usb/usbip/stub_main.c | 52 +++++---
> > drivers/usb/usbip/stub_rx.c | 207 ++++++++++++++++++++++---------
> > drivers/usb/usbip/stub_tx.c | 108 +++++++++++-----
> > drivers/usb/usbip/usbip_common.c | 60 +++++++--
> > drivers/usb/usbip/vhci_hcd.c | 29 ++++-
> > drivers/usb/usbip/vhci_tx.c | 49 ++++++--
> > 7 files changed, 391 insertions(+), 121 deletions(-)
> >
>
> Hi Suwan,
>
> I have been traveling and would like to test this series before I ask
> Greg to pick it up.
>
> Just a quick note that I will get to this early next week.

Ok. Thank you for reviewing the patch, Shuah.
Please let me know if you have any problems reviewing the patch :)

Regards

Suwan Kim

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