perusing kobject event code in lib/kobject_uevent.c and something puzzles me. early in kobject_uevent_env(), code guarantees that we find an ancestor kobject that has a valid kset: /* search the kset we belong to */ top_kobj = kobj; while (!top_kobj->kset && top_kobj->parent) top_kobj = top_kobj->parent; if (!top_kobj->kset) { pr_debug("kobject: '%s' (%p): %s: attempted to send uevent " "without kset!\n", kobject_name(kobj), kobj, __func__); return -EINVAL; } kset = top_kobj->kset; uevent_ops = kset->uevent_ops; so, as i read it, at that point, we're *guaranteed* to have found the closest kobject ancestor with a kset, and we save the relevant values in "kset" and "uevent_ops". so far, so good. but is there any guarantee that "uevent_ops" is non-null? a little below that, we read: if (uevent_ops && uevent_ops->filter) if (!uevent_ops->filter(kset, kobj)) { pr_debug("kobject: '%s' (%p): %s: filter function " "caused the event to drop!\n", kobject_name(kobj), kobj, __func__); return 0; } which clearly first tests if "uevent_ops" is non-null. so does that mean it might be? and the same check occurs twice more in that routine: ... /* originating subsystem */ if (uevent_ops && uevent_ops->name) subsystem = uevent_ops->name(kset, kobj); ... /* let the kset specific function add its stuff */ if (uevent_ops && uevent_ops->uevent) { ... is it really necessary to keep making that test? is there no way to simplify the code so that that test is done early, and reduces the subsequent code? just curious. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================