Le mercredi 18 janvier 2012 à 22:05 -0800, Hugh Dickins a écrit : > 2. Make one small adjustment to idr_get_next(): take the height from > the top layer (stable under RCU) instead of from the root (unprotected > by RCU), as idr_find() does. > > --- 3.2.0+/lib/idr.c 2012-01-04 15:55:44.000000000 -0800 > +++ linux/lib/idr.c 2012-01-18 21:25:36.947963342 -0800 > @@ -605,11 +605,11 @@ void *idr_get_next(struct idr *idp, int > int n, max; > > /* find first ent */ > - n = idp->layers * IDR_BITS; > - max = 1 << n; > p = rcu_dereference_raw(idp->top); > if (!p) > return NULL; > + n = (p->layer + 1) * IDR_BITS; > + max = 1 << n; > > while (id < max) { > while (n > 0 && p) { Interesting, but should be a patch on its own. Maybe other idr users can benefit from your idea as well, if patch is labeled "idr: allow idr_get_next() from rcu_read_lock" or something... I suggest introducing idr_get_next_rcu() helper to make the check about rcu cleaner. idr_get_next_rcu(...) { WARN_ON_ONCE(!rcu_read_lock_held()); return idr_get_next(...); } -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html