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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/