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SubjectRe: [PATCH v2 0/2] usbip: Implement SG support
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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.

thanks,
-- Shuah

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