On Fri, May 09, 2014 at 03:55:22PM -0400, Tejun Heo wrote: > Hello, > > On Fri, May 09, 2014 at 12:51:09PM -0700, Kent Overstreet wrote: > > Well not so much deprecated as "bad, avoid" - IMO using tryget() almost > > always > > (I haven't seen a convincing counterexample) means you screwed up your > > refcounting somewhere, if you need to take a ref on something whatever made > > that > > object visible to you should have its own ref. > > > > (I think we had this debate, but that was awhile ago...) > > Oh sure, tryget can definitely be misunderstood but RCU protected > iteration is one valid use case. > > rcu_read_lock(); > locate the object of interest; > tryget[_live]() depending on the use case; > rcu_read_unlock(); > > access the object.
No, it's not needed with RCU... look at the aio code for an example (or don't, save your eyes instead). Conceptually the RCU data structure should own a refcount on the things that are accessible via it; that ref shouldn't be dropped until after it's removed and an RCU barrier has happened. -- 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/
