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Date: Wed, 18 May 2011 12:42:12 -0700
From: Greg KH <gregkh@suse.de>
To: Alan Cox <alan@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Kay Sievers <kay.sievers@vrfy.org>, Arnd Bergmann <arnd@arndb.de>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: BUG: NULL pointer deref in tty port / uart
Message-ID: <20110518194212.GA27758@suse.de>
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On Wed, May 18, 2011 at 03:50:33PM +0100, Alan Cox wrote:
> > I think it's the 
> > 
> > uart_update_termios in uart_dtr_rts (drivers/tty/serial/serial_core.c)
> > 
> > called path:
> > 
> > tty_port_block_til_ready
> > 	tty_port_raise_dtr_rts
> > 		uart_dtr_rts
> > 			uart_update_termios
> 
> Ah that would explain why I can't find and dup it - it isn't found in
> the current -next tree.
> 
> 
> c7d7abff40c27f82fe78b1091ab3fad69b2546f9 (and thereafter)
> 
> Jiri Slaby fixed it in sorting out uart_startup
> 
> I guess these should now get tagged for -stable.

So that would be the following patches in the linux-next tree:
	c7d7abff40c27f82fe78b1091ab3fad69b2546f9 serial: core, move termios handling to uart_startup
	303a7a1199c20f7c9452f024a6e17bf348b6b398 serial: core, do not set DTR/RTS twice on startup
	6f5c24ad0f7619502199185a026a228174a27e68 serial: core, remove uart_update_termios

right?

Anything else need to be backported?

Frederic, can you test that these 3 patches solve the problem for you?
If you want, I can send them to you separately if you don't have a copy
of linux-next around anywhere.

thanks,

greg k-h