From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keshavamurthy Anil S Date: Wed, 10 Nov 2004 22:39:18 +0000 Subject: Re: [PATCH] kobject: fix double kobject_put in kobject_unregister() Message-Id: <20041110143918.B13668@unix-os.sc.intel.com> List-Id: References: <20041110141923.A13668@unix-os.sc.intel.com> <20041110223016.C26346@flint.arm.linux.org.uk> In-Reply-To: <20041110223016.C26346@flint.arm.linux.org.uk>; from rmk+lkml@arm.linux.org.uk on Wed, Nov 10, 2004 at 10:30:16PM +0000 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Russell King Cc: Keshavamurthy Anil S , Greg KH , Hotplug List , Linux Kernel On Wed, Nov 10, 2004 at 10:30:16PM +0000, Russell King wrote: > On Wed, Nov 10, 2004 at 02:19:23PM -0800, Keshavamurthy Anil S wrote: > > Hi Greg, > > > > This patch fixes the problem where in kobject resources were getting > > freed when those kobject were still in use due to double kobject_put() > > getting called in the kobject_unregister() code path. > > Isn't it intended that, after an sysfs/kobject/device object is > unregistered that the thread doing the unregistering must not > dereference the memory associated with that object? Yes, nobody is touching the resource once it is freed. But because of double kobject_put() getting called in the kobject_unregister() code patch I am seeing successive parent's kobject_unregister() causing panic as that kobject's kobject_cleanup() gets called when childs kobject_unregiser() is getting called. i.e patern's kobject_cleanup() gets called for some reason when clild's kobject_unregister() is called. My patch fixes this issues. > > IOW, the sequence: > > allocate > register (refcount >= 2 after this completes) > unregister > > will automatically free the object once the last user has gone. > > -- > Russell King > Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ > maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ > 2.6 Serial core ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_idU88&alloc_id065&op=click _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel