On Tue, Dec 31, 2013 at 12:40:16PM -0800, walt wrote: > On 12/18/2013 01:11 PM, Greg Kroah-Hartman wrote: > > 3.12-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: David Laight <david.lai...@aculab.com> > > > > commit 35773dac5f862cb1c82ea151eba3e2f6de51ec3e upstream. > > > > Section 4.11.7.1 of rev 1.0 of the xhci specification states that a link TRB > > can only occur at a boundary between underlying USB frames (512 bytes for > > high speed devices). > > > > If this isn't done the USB frames aren't formatted correctly and, for > > example, > > the USB3 ethernet ax88179_178a card will stop sending... > > > Unfortunately this patch causes a regression when copying large files to my > outboard USB3 drive. (Nothing at all to do with networking.) > > When I try to copy a large (20GB) file to the USB3 drive, the copy dies after > about 7GB, the ext4 journal aborts and the drive is remounted read-only. > > This bug is 100% reproducible (always pretty close to 7GB) and reverting this > patch completely fixes the problem.
Ok, I had feared that would be a consequence of this patch. I think the problem is that the usb-storage driver submitted an URB with more scatter-gather entries than would fit on the ring segment, the xHCI driver rejected the URB with -ENOMEM, and the SCSI core eventually gave up on the SCSI command. Do you have CONFIG_USB_DEBUG turned on for 3.13? If so, you should see dmesg output from this statement shortly before your drive fails: if (num_trbs >= TRBS_PER_SEGMENT) { xhci_err(xhci, "Too many fragments %d, max %d\n", num_trbs, TRBS_PER_SEGMENT - 1); return -ENOMEM; } > (Note to Sarah: I recently emailed you about this problem, and I *wrongly* > said that reverting the patch doesn't help. That was a mistake, sorry.) > > I'm happy to try any debugging suggestions/tricks. Unfortunately a real fix for this is going to take a bit. I have a couple different solutions to the bug the patch solved, but they're much more invasive than the original patch and will take a couple weeks to implement and thoroughly test. If David's patch is just reverted, USB ethernet on 3.12 and later breaks under xHCI. The networking folks added scatter-gather support in 3.12. Those patches could be reverted, but I suspect David Miller will not be happy with that solution, since the real problem is the xHCI driver itself, and EHCI scatter-gather works fine. I think the short term solution is to simply turn off scatter-gather all together under xHCI until this gets fixed. It could mean a big performance hit for USB storage devices, but that means we get correct behavior for both USB ethernet and USB storage. > BTW, please tell me if I've cc'd too many people. Nope, you're fine. I've Cc'ed the USB and SCSI mailing lists as well. Sarah Sharp -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html