Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932724Ab3CQRj5 (ORCPT ); Sun, 17 Mar 2013 13:39:57 -0400 Received: from netrider.rowland.org ([192.131.102.5]:33953 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756324Ab3CQRjy (ORCPT ); Sun, 17 Mar 2013 13:39:54 -0400 Date: Sun, 17 Mar 2013 13:39:53 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.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: 1860 Lines: 40 On Sun, 17 Mar 2013, Alan Stern wrote: > On Sun, 17 Mar 2013, Soeren Moch wrote: > > > For each device only one isochronous endpoint is used (EP IN4, 1x 940 > > Bytes, Interval 1). > > When the ENOMEM error occurs, a huge number of iTDs is in the free_list > > of one stream. This number is much higher than the 2*M entries, which > > should be there according to your description. > > Okay, but how did they get there? With each URB requiring 9 iTDs, and > about 5 URBs active at any time, there should be about 5*9 = 45 iTDs in > use and 2*9 = 18 iTDs on the free list. By the time each URB > completes, it should have released all 9 iTDs back to the free list, > and each time an URB is submitted, it should be able to acquire all 9 > of the iTDs that it needs from the free list -- it shouldn't have to > allocate any from the DMA pool. > > Looks like you'll have to investigate what's going on inside > itd_urb_transaction(). Print out some useful information whenever the > size of stream->free_list is above 50, such as the value of num_itds, > how many of the loop iterations could get an iTD from the free list, > and the value of itd->frame in the case where the "goto alloc_itd" > statement is followed. > > It might be a good idea also to print out the size of the free list in > itd_complete(), where it calls ehci_urb_done(), and include the value > of ehci->now_frame. One thing I forgot to mention: It would help to have millisecond precision for the timestamps in the system log, for comparison of frame number values. Please enable CONFIG_PRINTK_TIME for the next test. 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/