[ovs-dev] [ovs-dev v2] ofproto: add refcount to ofproto to fix crash at ofproto_destroy

Ben Pfaff blp at ovn.org
Tue Mar 2 00:07:54 UTC 2021

On Thu, Feb 25, 2021 at 10:31:35AM -0800, William Tu wrote:
> I think refcount and RCU are mutually exclusive. They are two
> different ways of doing synchronization and somehow we mix them
> together by using RCU to optimize refcount.

I think that you are correct in your description of the possibilities.
A data structure can be protected by RCU, or by a refcount, or by a
refcount that is only needed if access to a data structure needs to span
a grace period.  But to me, "mutually exclusive" means two things that
cannot exist together, and I think that the third possibility is in fact
a case where RCU and refcount exist together, so I would not call this
"mutually exclusive".

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