On Wed, Aug 10, 2005 at 03:36:36PM +0530, Maneesh Soni wrote: > On Wed, Aug 10, 2005 at 04:26:51PM +1000, Keith Owens wrote: > > FYI, the intermittent free after use in sysfs is still there in > > 2.6.13-rc6. > > > > The race condition is known here. It is some thing in the upper layer. > In this case "driver/base/class.c" which frees the kobject's attributes > even if there are live references to kobject. > > > open sysfs file unregister class device > sysfs_open_file() class_device_del() > -> takes a ref on kobject -> kfree attribute struct > -> accesses attributes -> kobject_del() > -> kref_put() > close sysfs file > sysfs_release() > -> acesses attributes using s_element > -> drops ref to kobject > > Solution could be either we have reference counting for attributes also > or keep attributes alive till the last reference to the kobject. Both these > needs changes in the driver core. > > Greg, will the following patch make sense? This postpones the kfree() of > devt_attr till class_dev_release() is called.
Yes, that patch looks good, if you fix up the space vs. tabs issue :) But will that really fix this race? I was under the impression the oops didn't come from trying to access the devt_attr, but the sysfs s_element pointer? > Please check this patch out, if this helps or not. I'd be interested in seeing if this fixes it. thanks, greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
