[ovs-dev] [netlink v3 4/5] vport: Add smp_wmb() to vport_alloc().
blp at nicira.com
Fri Dec 3 13:09:22 PST 2010
On Thu, Dec 02, 2010 at 06:52:26PM -0800, Jesse Gross wrote:
> On Tue, Nov 16, 2010 at 5:11 PM, Ben Pfaff <blp at nicira.com> wrote:
> > I'm not sure whether this is necessary or makes sense. If it does, then
> > it should be folded into the previous commit. If it doesn't, then this
> > commit should be dropped.
> I think it's probably generally unnecessary (it's certainly not needed
> by any of the current vport implementations). In order to receive
> packets on a different CPU, the vport would need to hand off the
> struct vport pointer somehow. To do that without any kind of memory
> barrier seems like a bug to me. Furthermore, the vport implementation
> is required to execute the corresponding read memory barrier, so it's
> better to be symmetrical.
OK, dropped this commit.
> Looking at vport_alloc() further, I would also drop the
> rcu_assign_pointer() in the assignment of params->dp to vport->dp from
> the last commit. We don't use rcu_dereference on read for it, so
> again it would good to be symmetrical.
OK, I made that change too.
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