linux-kernel - Re: [Fwd: [PATCH v2 0/4] TTY: port hangup and close fixes]

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Date:	Tue, 05 Mar 2013 22:56:57 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Peter Hurley <peter@...leysoftware.com>
CC:	jhovold@...il.com, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	USB list <linux-usb@...r.kernel.org>,
	linux-serial@...r.kernel.org, Alan Cox <alan@...rguk.ukuu.org.uk>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Fwd: [PATCH v2 0/4] TTY: port hangup and close fixes]

On 03/05/2013 06:06 PM, Peter Hurley wrote:
>>> @@ -225,15 +232,13 @@ void tty_port_hangup(struct tty_port *port)
>>         spin_lock_irqsave(&port->lock, flags);
>>         port->count = 0;
>>         port->flags &= ~ASYNC_NORMAL_ACTIVE;
>> -       if (port->tty) {
>> +       if (port->tty)
>>                 set_bit(TTY_IO_ERROR, &port->tty->flags);
>> -               tty_kref_put(port->tty);
>> -       }
>> -       port->tty = NULL;
>>         spin_unlock_irqrestore(&port->lock, flags);
>>> +       tty_port_shutdown(port, port->tty);
>>
>> What prevents port->tty to be NULL here already?
> 
> Nothing. That's why it's tested in tty_port_shutdown() above.

I know :). But the question is rather don't we want to pass the real
refcounted port->tty (take a snapshot inside the lock) instead?

thanks,
-- 
js
suse labs
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