Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422806AbXBALQf (ORCPT ); Thu, 1 Feb 2007 06:16:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422805AbXBALQe (ORCPT ); Thu, 1 Feb 2007 06:16:34 -0500 Received: from caramon.arm.linux.org.uk ([217.147.92.249]:3904 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422808AbXBALQd (ORCPT ); Thu, 1 Feb 2007 06:16:33 -0500 Date: Thu, 1 Feb 2007 11:16:18 +0000 From: Russell King To: Aubrey Li Cc: Alan , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [BUG]: 2.6.19.2: Weird serial core issue Message-ID: <20070201111618.GA3462@flint.arm.linux.org.uk> Mail-Followup-To: Aubrey Li , Alan , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org References: <6d6a94c50701310249o2b2c8024i4d3f28ec1601246a@mail.gmail.com> <20070131162123.67e22e23@localhost.localdomain> <6d6a94c50701311833m5952c6fdn8e1f0db28d674e79@mail.gmail.com> <20070201094522.GA24608@flint.arm.linux.org.uk> <6d6a94c50702010209t94964ew1aebfad2677aa315@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6d6a94c50702010209t94964ew1aebfad2677aa315@mail.gmail.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1886 Lines: 47 On Thu, Feb 01, 2007 at 06:09:24PM +0800, Aubrey Li wrote: > On 2/1/07, Russell King wrote: > >On Thu, Feb 01, 2007 at 10:33:40AM +0800, Aubrey Li wrote: > >> On 2/1/07, Alan wrote: > >> >What code is running on that console at the time. Most likely that user > >> >code is also saving/restoring terminal settings so overwrite yours > >> > > >> > >> I implemented the serial driver by myself, :). See the attachment. > >> I didn't save/restore terminal setting in the my_set_termios(). > >> > >> I trace this back till tty_tioctl(..., unsigned long arg), everytime I > >> type "ENTER" key, > >> the argument "arg" passed into tty_ioctl() is the address of a termios > >> structure, which include wrong c_cflag. > > > >If userspace is issuing an ioctl to re-enable crtscts, and the kernel > >is obliging, how can this be a kernel bug? > > But the fact is not. > 1) kernel boot up and enable crtscts by default > 2) issue an ioctl to disable crtscts. > 3) not do anything but type "ENTER", kernel re-enable crtscts. > > That's wrong. Terminal setting seems not be recorded by the serial core. serial core does not and should not "record" the terminal settings. That's the job of the tty layer. > Is it clear? No. You haven't analysed the call path causing tty_ioctl() to be invoked, so you have no basis to point the finger *anywhere* at the moment. Find out from where tty_ioctl() is called - maybe by adding a call to dump_stack(). I think you'll find it is coming from userspace. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: - 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/