> From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-owner@xxxxxxxxxxxxxxx] On Behalf Of David Laight > Sent: Wednesday, November 20, 2013 9:16 AM > > > Ok, so the networking layer should be fine. However, with the current > > patch, if the mass storage driver sends down a scatter-gather list > > that's bigger than a ring segment, or needs to be split up so it doesn't > > cross 64K boundaries, then the URB submission will fail. We don't want > > that to happen. > > My suspicion is that long SG lists are unusual - otherwise the > ring expansion code would have been needed much earlier. > > Can anyone remember whether that was needed because of long SG lists > or because of large numbers of outstanding requests? > > I've seen it for network cards - but only because usbnet sends > down far too many tx buffers. usb-storage limits the maximum transfer size to 120K. That is a max of 31 page-size segments if my math is right. That's probably why mass-storage never saw a problem. -- Paul -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
