From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Aubrey Li <aubreylee@gmail.com>
Cc: Alan <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [BUG]: 2.6.19.2: Weird serial core issue
Date: Thu, 1 Feb 2007 11:16:18 +0000 [thread overview]
Message-ID: <20070201111618.GA3462@flint.arm.linux.org.uk> (raw)
In-Reply-To: <6d6a94c50702010209t94964ew1aebfad2677aa315@mail.gmail.com>
On Thu, Feb 01, 2007 at 06:09:24PM +0800, Aubrey Li wrote:
> On 2/1/07, Russell King <rmk+lkml@arm.linux.org.uk> wrote:
> >On Thu, Feb 01, 2007 at 10:33:40AM +0800, Aubrey Li wrote:
> >> On 2/1/07, Alan <alan@lxorguk.ukuu.org.uk> 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:
next prev parent reply other threads:[~2007-02-01 11:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-31 10:49 [BUG]: 2.6.19.2: Weird serial core issue Aubrey Li
2007-01-31 16:21 ` Alan
2007-02-01 2:33 ` Aubrey Li
2007-02-01 9:45 ` Russell King
2007-02-01 10:09 ` Aubrey Li
2007-02-01 11:16 ` Russell King [this message]
2007-02-01 17:54 ` Aubrey Li
2007-02-01 19:09 ` Russell King
2007-02-02 3:34 ` Christopher Curtis
[not found] ` <000201c745d9$4577fe20$2e01a8c0@acksys.local>
2007-02-01 10:38 ` Aubrey Li
2007-02-01 15:19 ` Paul Fulghum
2007-02-01 12:02 ` Alan
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