[PATCH 0/2] usbip: Implement SG support to vhci

[Suwan Kim <suwan.kim027@gmail.com>]

There are bugs on vhci with usb 3.0 storage device. Originally, vhci
doesn't supported SG. So, USB storage driver on vhci divides SG list
into multiple URBs and it causes buffer overflow on the xhci of the
server. So we need to add SG support to vhci

In this patch series, vhci doesn't map and unmap URB for DMA to use
native SG list (urb->num_sgs). When vhci supports SG, it is useful
to use native SG list instead of mapped SG list because dma mapping
fnuction can adjust the number of SG list that is urb->num_mapped_sgs.

"usbip: Skip DMA mapping and unmapping for urb at vhci" is originally
submitted as separate patch, but I include it in this patch series
because it is needed to implement SG support of vhci.

In this patch, vhci basically support SG and it sends each SG list
entry to the stub driver. Then, the stub driver sees 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 the vhci.
    
If HCD of server doesn't support SG, the stub driver allocates
big buffer using kmalloc() instead of using sgl_alloc() which
allocates SG list and pages.
    
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_rx.c      | 32 +++++++++++++----
 drivers/usb/usbip/stub_tx.c      | 53 +++++++++++++++++++++++-----
 drivers/usb/usbip/usbip_common.c | 60 +++++++++++++++++++++++++++-----
 drivers/usb/usbip/usbip_common.h |  2 ++
 drivers/usb/usbip/vhci_hcd.c     | 23 +++++++++++-
 drivers/usb/usbip/vhci_tx.c      | 49 ++++++++++++++++++++------
 6 files changed, 184 insertions(+), 35 deletions(-)

-- 
2.20.1