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.
It's not different from why we use atomic_inc_not_zero() in some
places. The only difference is that percpu_ref distinguishes live
vs. dying states. It's true that this can be used in pretty stupid
ways but I think the comments are pretty clear on that. Do you think
we need more warning there?
Thanks.
--
tejun
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