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SubjectRe: [PATCH 1/2] ttyprintk: Fix wrong tty_unregister_driver() call in the error path
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 <jdelvare@suse.de>
> > Signed-off-by: Takashi Iwai <tiwai@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 <jdelvare@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?


thanks,

Takashi
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