From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [RFC] Suspicious bug in module refcounting Date: Wed, 4 Feb 2009 21:25:47 +1030 Message-ID: <200902042125.48723.rusty@rustcorp.com.au> References: <20090203134721.GA11069@pingi.kke.suse.de> <200902041418.09630.rusty@rustcorp.com.au> <20090204101130.GB19498@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Karsten Keil , linux-kernel@vger.kernel.org, Michal Hocko , richard kennedy , Dan Williams , Dmitry Torokhov , dwmw2@infradead.org, Scott Wood , netdev@vger.kernel.org, Al Viro To: Russell King Return-path: Received: from ozlabs.org ([203.10.76.45]:57072 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751771AbZBDK4A (ORCPT ); Wed, 4 Feb 2009 05:56:00 -0500 In-Reply-To: <20090204101130.GB19498@flint.arm.linux.org.uk> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: On Wednesday 04 February 2009 20:41:30 Russell King wrote: > On Wed, Feb 04, 2009 at 02:18:08PM +1030, Rusty Russell wrote: > > gameport.c, serio.c and input.c increment their own refcount, but to get > > into those init functions someone must be holding a refcount already (ie. a > > module depends on this module). Ditto cyber2000fb.c, and MTD. > > Err, wrong. cyber2000fb.c does it in its module initialization function > to prevent the module (when built for Shark) from being unloaded. It > does this because it's from the days of 2.2 kernels and no one bothered > writing the module unload support for Shark. I'm certainly not in a > position to do that. Thanks, here's the patch then: Subject: cyber2000fb.c: use proper method for stopping unload if CONFIG_ARCH_SHARK Russell explains the __module_get(): > cyber2000fb.c does it in its module initialization function > to prevent the module (when built for Shark) from being unloaded. It > does this because it's from the days of 2.2 kernels and no one bothered > writing the module unload support for Shark. Since 2.4, the correct answer has been to not define an unload fn. Cc: Russell King Signed-off-by: Rusty Russell diff --git a/drivers/video/cyber2000fb.c b/drivers/video/cyber2000fb.c --- a/drivers/video/cyber2000fb.c +++ b/drivers/video/cyber2000fb.c @@ -1736,10 +1736,8 @@ static int __init cyber2000fb_init(void) #ifdef CONFIG_ARCH_SHARK err = cyberpro_vl_probe(); - if (!err) { + if (!err) ret = 0; - __module_get(THIS_MODULE); - } #endif #ifdef CONFIG_PCI err = pci_register_driver(&cyberpro_driver); @@ -1749,14 +1747,15 @@ static int __init cyber2000fb_init(void) return ret ? err : 0; } +module_init(cyber2000fb_init); +#ifndef CONFIG_ARCH_SHARK static void __exit cyberpro_exit(void) { pci_unregister_driver(&cyberpro_driver); } - -module_init(cyber2000fb_init); module_exit(cyberpro_exit); +#endif MODULE_AUTHOR("Russell King"); MODULE_DESCRIPTION("CyberPro 2000, 2010 and 5000 framebuffer driver");