net: rcu-ify tcf_proto
rcu'ify tcf_proto this allows calling tc_classify() without holding
any locks. Updaters are protected by RTNL.
This patch prepares the core net_sched infrastracture for running
the classifier/action chains without holding the qdisc lock however
it does nothing to ensure cls_xxx and act_xxx types also work without
locking. Additional patches are required to address the fall out.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 58bed75..ca62483 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1781,7 +1781,7 @@
__be16 protocol = skb->protocol;
int err;
- for (; tp; tp = tp->next) {
+ for (; tp; tp = rcu_dereference_bh(tp->next)) {
if (tp->protocol != protocol &&
tp->protocol != htons(ETH_P_ALL))
continue;
@@ -1833,15 +1833,15 @@
{
tp->ops->destroy(tp);
module_put(tp->ops->owner);
- kfree(tp);
+ kfree_rcu(tp, rcu);
}
-void tcf_destroy_chain(struct tcf_proto **fl)
+void tcf_destroy_chain(struct tcf_proto __rcu **fl)
{
struct tcf_proto *tp;
- while ((tp = *fl) != NULL) {
- *fl = tp->next;
+ while ((tp = rtnl_dereference(*fl)) != NULL) {
+ RCU_INIT_POINTER(*fl, tp->next);
tcf_destroy(tp);
}
}