[ovs-dev] classifier versioning and rule_dpif_try_ref()

Jarno Rajahalme jrajahalme at nicira.com
Sat Aug 1 18:03:49 UTC 2015


> On Jul 31, 2015, at 21:54, Ben Pfaff <blp at nicira.com> wrote:
> 
> Now that the classifier is versioned, is it still possible for
> rule_dpif_try_ref() to return false?  Specifically, can we change the
> loop in rule_dpif_lookup_in_table() to do an ordinary ref instead of a
> try_ref?
> 
> My motive is that, if we could change it, then we could drop the
> 'take_ref' parameter from rule_dpif_lookup_from_table(), instead letting
> the caller take the ref if it wants it, which seems like a cleaner
> interface.  But, of course, correctness is more important.
> 

Right, now rule removal is rcu postponed after a version bump, so the rule is not removed while the lookup on the old version is in progress, so it is safe to make this change.

  Jarno

> Thanks,
> 
> Ben.



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