Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755504AbbDGPaU (ORCPT ); Tue, 7 Apr 2015 11:30:20 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:33939 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754878AbbDGPaR (ORCPT ); Tue, 7 Apr 2015 11:30:17 -0400 Date: Tue, 7 Apr 2015 11:30:15 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Johan Hovold cc: Greg Kroah-Hartman , Felipe Balbi , , , Stephen Warren , Thierry Reding , Alexandre Courbot , , stable Subject: Re: [PATCH 2/2] USB: ehci-tegra: fix inefficient copy of unaligned buffers In-Reply-To: <1428400012-7563-3-git-send-email-johan@kernel.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 956 Lines: 23 On Tue, 7 Apr 2015, Johan Hovold wrote: > Make sure only to copy any actual data rather than the whole buffer, > when releasing the temporary buffer used for unaligned transfer buffers. > > Note that the corresponding fix of musb also fixes a lockup on > disconnect, where repeated failed transfers would starve the hub > workqueue from processing the disconnect, which would have prevented the > urbs from being resubmitted. In this case there is no data to forward, > but the full buffer length was being copied nonetheless. This is wrong for isochronous transfers, because the transfer data generally isn't contiguous in memory. It would be okay to do this for other transfer types, though. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/