10e232c597
USB spec stats that short packet can only appear at the end of transfer. Because lost of HC(EHCI/UHCI/OHCI/...) can't build a full packet from discontinuous buffers, we introduce the limit in usb_submit_urb() to avoid such kind of bad sg buffers coming from driver. The limit might be a bit strict: - platform has iommu to do sg list mapping - some host controllers may support to build full packet from discontinuous buffers. But considered that most of HCs don't support that, and driver need work well or keep consistent on different HCs and ARCHs, we have to introduce the limit. Currently, only usbtest is reported to pass such sg buffers to HC, and other users(mass storage, usbfs) don't have the problem. We don't check it on USB wireless device, because: - wireless devices can't be attached to common USB bus(EHCI/UHCI/OHCI/...) - the max packet size of endpoint may be odd, and often can't devide 4KB which is a typical usage in usb mass storage application Reported-by: Konstantin Filatov <kfilatov@parallels.com> Reported-by: Denis V. Lunev <den@openvz.org> Cc: Felipe Balbi <balbi@ti.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|---|---|---|
| .. | ||
| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
| dt-bindings | ||
| keys | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| rxrpc | ||
| scsi | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| video | ||
| xen | ||
| Kbuild | ||