Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162528AbaDCIAc (ORCPT ); Thu, 3 Apr 2014 04:00:32 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:56381 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162430AbaDCIAa (ORCPT ); Thu, 3 Apr 2014 04:00:30 -0400 Message-ID: <533D151A.9070808@suse.cz> Date: Thu, 03 Apr 2014 10:00:26 +0200 From: Jiri Slaby User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Takashi Iwai CC: Samo Pogacnik , Jean Delvare , Arnd Bergmann , Greg Kroah-Hartman , Struan Bartlett , Andreas Schwab , gnomes@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] ttyprintk: Fix wrong tty_unregister_driver() call in the error path References: <1396434582-30799-1-git-send-email-tiwai@suse.de> <1396441473.10789.23.camel@chaos.site> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >>> Signed-off-by: Takashi Iwai >>> --- >>> 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 > > 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/