From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFD driver-core] Lifetime problems of the current driver model Date: Sun, 01 Apr 2007 01:14:15 +0900 Message-ID: <460E88D7.3010702@gmail.com> References: <460CDBA6.5030608@gmail.com> <20070330151926.18fc12a0@gondolin.boeblingen.de.ibm.com> <460D0E78.3040200@gmail.com> <20070330154042.4c7deb72@gondolin.boeblingen.de.ibm.com> <460D178F.4000500@gmail.com> <20070330165251.7beffc7c@gondolin.boeblingen.de.ibm.com> <460D27E3.2050602@gmail.com> <20070330213101.7aa7babf@gondolin.boeblingen.de.ibm.com> <460DD1B0.4080605@gmail.com> <20070331180806.55d572c8@gondolin.boeblingen.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from nz-out-0506.google.com ([64.233.162.236]:31108 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753312AbXCaQOX (ORCPT ); Sat, 31 Mar 2007 12:14:23 -0400 Received: by nz-out-0506.google.com with SMTP id s1so683581nze for ; Sat, 31 Mar 2007 09:14:22 -0700 (PDT) In-Reply-To: <20070331180806.55d572c8@gondolin.boeblingen.de.ibm.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Cornelia Huck Cc: gregkh@suse.de, hugh@veritas.com, dmitry.torokhov@gmail.com, oneukum@suse.de, maneesh@in.ibm.com, rpurdie@rpsys.net, James.Bottomley@SteelEye.com, Jeff Garzik , lkml , "linux-ide@vger.kernel.org" , SCSI Mailing List Cornelia Huck wrote: > On Sat, 31 Mar 2007 12:12:48 +0900, > Tejun Heo wrote: > >>> Hm, but as long as dk0 is registered, it can be looked up and someone >>> could get a reference on it. >> Yeah, exactly. That's why any getting any kobject reference backed by a >> module must be accompanied by try_module_get(). >> >> int mydrv_get_dk(struct dk *dk) >> { >> rc = try_module_get(mydrv); >> if (rc) >> return rc; >> kobject_get(&dk->kobj); >> return 0; >> } > > This works if the caller always knows which module to grab (I was > thinking about some tree-walking code). Yeah, that's why we have so many ->owner's and getting it wrong results in jumping to non-existent address. -- tejun