From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx119.postini.com [74.125.245.119]) by kanga.kvack.org (Postfix) with SMTP id 92C4D6B0037 for ; Thu, 21 Mar 2013 18:16:28 -0400 (EDT) Message-ID: <514B86A9.60401@web.de> Date: Thu, 21 Mar 2013 23:16:09 +0100 From: Soeren Moch MIME-Version: 1.0 Subject: Re: [PATCH] USB: EHCI: fix for leaking isochronous data References: <20130321212033.GQ21478@lunn.ch> In-Reply-To: <20130321212033.GQ21478@lunn.ch> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Alan Stern Cc: Andrew Lunn , Arnd Bergmann , USB list , Jason Cooper , Sebastian Hesselbarth , linux-mm@kvack.org, Kernel development list , linux-arm-kernel@lists.infradead.org, michael@amarulasolutions.com On 21.03.2013 22:20, Andrew Lunn wrote: > On Thu, Mar 21, 2013 at 05:12:01PM -0400, Alan Stern wrote: >> 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. > > Hi Alan, Soeren > > Could you word the description a bit better. If Alan did not get it > without a bit of thought, few others are going to understand it > without a better explanation. > > Thanks > Andrew > Alan, can you come up with a better explanation, please? I think your description how it is supposed to work from here http://marc.info/?l=linux-usb&m=136345559432055&w=2 is required to understand the problem and the fix. Thanks, Soeren -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org