From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754188Ab0ASPPj (ORCPT ); Tue, 19 Jan 2010 10:15:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753834Ab0ASPPe (ORCPT ); Tue, 19 Jan 2010 10:15:34 -0500 Received: from smtp-out003.kontent.com ([81.88.40.217]:42729 "EHLO smtp-out003.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752167Ab0ASPPI (ORCPT ); Tue, 19 Jan 2010 10:15:08 -0500 From: Oliver Neukum To: Alan Cox Subject: Re: [REGRESSION] "USB: use kfifo to buffer usb-generic serial writes" causes gobi_loader to hang Date: Tue, 19 Jan 2010 16:15:47 +0100 User-Agent: KMail/1.12.2 (Linux/2.6.33-rc3-0.1-default; KDE/4.3.1; x86_64; ; ) Cc: Matthew Garrett , dvomlehn@cisco.com, gregkh@suse.de, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <20100117025535.GB7045@srcf.ucam.org> <201001191457.00504.oliver@neukum.org> <20100119142124.6f2a7034@lxorguk.ukuu.org.uk> In-Reply-To: <20100119142124.6f2a7034@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201001191615.47589.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, 19. Januar 2010 15:21:24 schrieb Alan Cox: > > > > If the FIFO is full we can do nothing. Please try the attached patch. > > > > > > If the FIFO is full how are we getting called - we should have throttled > > > earlier if there is any flow control (including 'look no URBs' cases) ? > > > > The log shows no call to usb_serial_generic_write_room() > > Do you consider this a bug in the tty layer? > > Some of the line disciplines just throw data at the board but not n_tty > (the normal one) - so for PPP you wouldn't see checks on room but the > loader I assume is using the normal tty layer - if so something is up > because the ldisc shouldn't have written more than there is room for. I don't know which line discipline is used. Matthew? But anyway, if this can happen buglessly, the generic function must handle it. Regards Oliver