From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx180.postini.com [74.125.245.180]) by kanga.kvack.org (Postfix) with SMTP id 7CD3F6B0002 for ; Thu, 21 Mar 2013 17:06:55 -0400 (EDT) Date: Thu, 21 Mar 2013 17:06:54 -0400 (EDT) From: Alan Stern Subject: Re: [PATCH] USB: EHCI: fix for leaking isochronous data In-Reply-To: <514B3DBB.3060302@web.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Soeren Moch Cc: Arnd Bergmann , USB list , Jason Cooper , Andrew Lunn , Sebastian Hesselbarth , linux-mm@kvack.org, Kernel development list , linux-arm-kernel@lists.infradead.org, michael@amarulasolutions.com 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. > The attached patch > invalidates the frame number in each iTD before it is sent to the > scheduler. This fixes the problem without the need to iterate over a iTD > list. The patch looks okay. However I would like to understand why the 0 frame value messes things up so much. Alan Stern -- 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