On Thu, Jun 20, 2013 at 05:32:44PM -0700, Tejun Heo wrote: > list_first_or_null() should test whether the list is empty and return > pointer to the first entry if not in a RCU safe manner. It's broken > in two ways. > > * It compares __kernel @__ptr with __rcu @__next triggering the > following sparse warning. > > net/core/dev.c:4331:17: error: incompatible types in comparison expression > (different address spaces) > > * It doesn't perform rcu_dereference*() and computes the entry address > using container_of() directly from the __rcu pointer which is > inconsitent with other rculist interface. As a result, all three > in-kernel users - net/core/dev.c, macvlan, cgroup - are buggy. They > dereference the pointer w/o going through read barrier. > > Fix it by making list_first_or_null_rcu() dereference ->next directly > and then use list_entry_rcu() on it like other rculist accessors. > > Signed-off-by: Tejun Heo <[email protected]> > Reported-by: Fengguang Wu <[email protected]> > Cc: Dipankar Sarma <[email protected]> > Cc: "Paul E. McKenney" <[email protected]> > Cc: "David S. Miller" <[email protected]> > Cc: Li Zefan <[email protected]> > Cc: Patrick McHardy <[email protected]> > Cc: [email protected]
Paul, ping. -- tejun -- 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/
