[NETNS][DST] dst: pass the dst_ops as parameter to the gc functions

The garbage collection function receive the dst_ops structure as
parameter. This is useful for the next incoming patchset because it
will need the dst_ops (there will be several instances) and the
network namespace pointer (contained in the dst_ops).

The protocols which do not take care of the namespaces will not be
impacted by this change (expect for the function signature), they do
just ignore the parameter.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/dst.h b/include/net/dst.h
index e03ea0c..e24a416 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -89,7 +89,7 @@
 	__be16			protocol;
 	unsigned		gc_thresh;
 
-	int			(*gc)(void);
+	int			(*gc)(struct dst_ops *ops);
 	struct dst_entry *	(*check)(struct dst_entry *, __u32 cookie);
 	void			(*destroy)(struct dst_entry *);
 	void			(*ifdown)(struct dst_entry *,