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_atm.c b/net/sched/sch_atm.c
index 8449b33..c398f9c 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -41,7 +41,7 @@
struct atm_flow_data {
struct Qdisc *q; /* FIFO, TBF, etc. */
- struct tcf_proto *filter_list;
+ struct tcf_proto __rcu *filter_list;
struct atm_vcc *vcc; /* VCC; NULL if VCC is closed */
void (*old_pop)(struct atm_vcc *vcc,
struct sk_buff *skb); /* chaining */
@@ -273,7 +273,7 @@
error = -ENOBUFS;
goto err_out;
}
- flow->filter_list = NULL;
+ RCU_INIT_POINTER(flow->filter_list, NULL);
flow->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid);
if (!flow->q)
flow->q = &noop_qdisc;
@@ -311,7 +311,7 @@
pr_debug("atm_tc_delete(sch %p,[qdisc %p],flow %p)\n", sch, p, flow);
if (list_empty(&flow->list))
return -EINVAL;
- if (flow->filter_list || flow == &p->link)
+ if (rcu_access_pointer(flow->filter_list) || flow == &p->link)
return -EBUSY;
/*
* Reference count must be 2: one for "keepalive" (set at class
@@ -345,7 +345,8 @@
}
}
-static struct tcf_proto **atm_tc_find_tcf(struct Qdisc *sch, unsigned long cl)
+static struct tcf_proto __rcu **atm_tc_find_tcf(struct Qdisc *sch,
+ unsigned long cl)
{
struct atm_qdisc_data *p = qdisc_priv(sch);
struct atm_flow_data *flow = (struct atm_flow_data *)cl;
@@ -369,11 +370,12 @@
flow = NULL;
if (TC_H_MAJ(skb->priority) != sch->handle ||
!(flow = (struct atm_flow_data *)atm_tc_get(sch, skb->priority))) {
+ struct tcf_proto *fl;
+
list_for_each_entry(flow, &p->flows, list) {
- if (flow->filter_list) {
- result = tc_classify_compat(skb,
- flow->filter_list,
- &res);
+ fl = rcu_dereference_bh(flow->filter_list);
+ if (fl) {
+ result = tc_classify_compat(skb, fl, &res);
if (result < 0)
continue;
flow = (struct atm_flow_data *)res.class;
@@ -544,7 +546,7 @@
if (!p->link.q)
p->link.q = &noop_qdisc;
pr_debug("atm_tc_init: link (%p) qdisc %p\n", &p->link, p->link.q);
- p->link.filter_list = NULL;
+ RCU_INIT_POINTER(p->link.filter_list, NULL);
p->link.vcc = NULL;
p->link.sock = NULL;
p->link.classid = sch->handle;