On 04/03/2014 08:10 AM, Takashi Iwai wrote:
> At Wed, 02 Apr 2014 14:24:33 +0200,
> Jean Delvare wrote:
>>
>> Le Wednesday 02 April 2014 à 12:29 +0200, Takashi Iwai a écrit :
>>> ttyprintk driver calls tty_unregister_driver() wrongly in the error
>>> path of tty_register_driver(). Also, setting ttyprintk_driver to NULL
>>> is utterly superfluous, so let's get rid of it, too.
>>>
>>> Reported-by: Jean Delvare <jdelv...@suse.de>
>>> Signed-off-by: Takashi Iwai <ti...@suse.de>
>>> ---
>>> drivers/char/ttyprintk.c | 2 --
>>> 1 file changed, 2 deletions(-)
>>>
>>> diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
>>> index daea84c41743..2a39c5790364 100644
>>> --- a/drivers/char/ttyprintk.c
>>> +++ b/drivers/char/ttyprintk.c
>>> @@ -210,10 +210,8 @@ static int __init ttyprintk_init(void)
>>> return 0;
>>>
>>> error:
>>> - tty_unregister_driver(ttyprintk_driver);
>>> put_tty_driver(ttyprintk_driver);
>>> tty_port_destroy(&tpk_port.port);
>>> - ttyprintk_driver = NULL;
>>> return ret;
>>> }
>>> device_initcall(ttyprintk_init);
>>
>> Reviewed-by: Jean Delvare <jdelv...@suse.de>
>
> Meanwhile, I found that tty_unregister_driver() was added
> intentionally in the commit f06fb543c1d0,
> TTY: ttyprintk, unregister tty driver on failure
>
> When the tty_printk driver fails to create a node in sysfs, the
> system
> crashes. It is because the driver registers a tty driver and frees
> it
> without deregistering it first. The fix is easy: add a call to
> tty_unregister_driver to the fail path.
>
> But, I failed to see why this is needed in the current code.
>
> Jiri, is your fix still valid at all?
The code was different. There was also device_create after
tty_register_driver. I must admit that I don't know why I didn't change
'goto error' in the tty_register_driver fail path.
ret = tty_register_driver(ttyprintk_driver);
if (ret < 0) {
printk(KERN_ERR "Couldn't register ttyprintk driver\n");
goto error;
}
/* create our unnumbered device */
rp = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 3), NULL,
ttyprintk_driver->name);
if (IS_ERR(rp)) {
printk(KERN_ERR "Couldn't create ttyprintk device\n");
ret = PTR_ERR(rp);
goto error;
}
So yes, there should be no tty_unregister_driver in the fail path when
device_create is gone now.
thanks,
--
js
suse labs
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