Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753408Ab3CUVMF (ORCPT ); Thu, 21 Mar 2013 17:12:05 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:38390 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753256Ab3CUVMC (ORCPT ); Thu, 21 Mar 2013 17:12:02 -0400 Date: Thu, 21 Mar 2013 17:12:01 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Soeren Moch cc: Arnd Bergmann , USB list , Jason Cooper , Andrew Lunn , Sebastian Hesselbarth , , Kernel development list , , Subject: Re: [PATCH] USB: EHCI: fix for leaking isochronous data In-Reply-To: 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: 1264 Lines: 31 On Thu, 21 Mar 2013, Alan Stern wrote: > On Thu, 21 Mar 2013, Soeren Moch wrote: > > > Now I found out what is going on here: > > > > In itd_urb_transaction() we allocate 9 iTDs for each URB with > > number_of_packets == 64 in my case. The iTDs are added to > > sched->td_list. For a frame-aligned scheduling we need 8 iTDs, the 9th > > one is released back to the front of the streams free_list in > > iso_sched_free(). This iTD was cleared after allocation and has a frame > > number of 0 now. So for each allocation when now_frame == 0 we allocate > > from the dma_pool, not from the free_list. > > Okay, that is a problem. But it shouldn't be such a big problem, > because now_frame should not be equal to 0 very often. Oh, wait, now I get it. We never reach a steady state, because the free list never shrinks, but occasionally it does increase when now_frame is equal to 0. Even though that doesn't happen very often, the effects add up. Very good; tomorrow I will send your patch in. 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/