All users of chain->filters_chain rely on rtnl lock and assume that no new
classifier instances are added when traversing the list. Use
tcf_get_next_proto() to traverse filters list without relying on rtnl
mutex. This function iterates over classifiers by taking reference to
current iterator classifier only and doesn't assume external
synchronization of filters list.
Signed-off-by: Vlad Buslov <vla...@mellanox.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
---
include/net/pkt_cls.h | 2 ++
net/sched/cls_api.c | 70 +++++++++++++++++++++++++++++++++++++++++++--------
net/sched/sch_api.c | 4 +--
3 files changed, 64 insertions(+), 12 deletions(-)
diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index 8396d51e78a1..727cb99da5d4 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -45,6 +45,8 @@ struct tcf_chain *tcf_chain_get_by_act(struct tcf_block
*block,
void tcf_chain_put_by_act(struct tcf_chain *chain);
struct tcf_chain *tcf_get_next_chain(struct tcf_block *block,
struct tcf_chain *chain);
+struct tcf_proto *tcf_get_next_proto(struct tcf_chain *chain,
+ struct tcf_proto *tp);
void tcf_block_netif_keep_dst(struct tcf_block *block);
int tcf_block_get(struct tcf_block **p_block,
struct tcf_proto __rcu **p_filter_chain, struct Qdisc *q,
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 6cbdb28017d3..02130f8d89e1 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -728,6 +728,45 @@ tcf_get_next_chain(struct tcf_block *block, struct
tcf_chain *chain)
}
EXPORT_SYMBOL(tcf_get_next_chain);
+static struct tcf_proto *
+__tcf_get_next_proto(struct tcf_chain *chain, struct tcf_proto *tp)
+{
+ ASSERT_RTNL();
+ spin_lock(&chain->filter_chain_lock);
+
+ if (!tp)
+ tp = tcf_chain_dereference(chain->filter_chain, chain);
+ else
+ tp = tcf_chain_dereference(tp->next, chain);
+
+ if (tp)
+ tcf_proto_get(tp);
+
+ spin_unlock(&chain->filter_chain_lock);
+
+ return tp;
+}
+
+/* Function to be used by all clients that want to iterate over all tp's on
+ * chain. Users of this function must be tolerant to concurrent tp
+ * insertion/deletion or ensure that no concurrent chain modification is
+ * possible. Note that all netlink dump callbacks cannot guarantee to provide
+ * consistent dump because rtnl lock is released each time skb is filled with
+ * data and sent to user-space.
+ */
+
+struct tcf_proto *
+tcf_get_next_proto(struct tcf_chain *chain, struct tcf_proto *tp)
+{
+ struct tcf_proto *tp_next = __tcf_get_next_proto(chain, tp);
+
+ if (tp)
+ tcf_proto_put(tp, NULL);
+
+ return tp_next;
+}
+EXPORT_SYMBOL(tcf_get_next_proto);
+
static void tcf_block_flush_all_chains(struct tcf_block *block)
{
struct tcf_chain *chain;
@@ -1100,7 +1139,7 @@ tcf_block_playback_offloads(struct tcf_block *block,
tc_setup_cb_t *cb,
struct netlink_ext_ack *extack)
{
struct tcf_chain *chain, *chain_prev;
- struct tcf_proto *tp;
+ struct tcf_proto *tp, *tp_prev;
int err;
for (chain = __tcf_get_next_chain(block, NULL);
@@ -1108,8 +1147,10 @@ tcf_block_playback_offloads(struct tcf_block *block,
tc_setup_cb_t *cb,
chain_prev = chain,
chain = __tcf_get_next_chain(block, chain),
tcf_chain_put(chain_prev)) {
- for (tp = rtnl_dereference(chain->filter_chain); tp;
- tp = rtnl_dereference(tp->next)) {
+ for (tp = __tcf_get_next_proto(chain, NULL); tp;
+ tp_prev = tp,
+ tp = __tcf_get_next_proto(chain, tp),
+ tcf_proto_put(tp_prev, NULL)) {
if (tp->ops->reoffload) {
err = tp->ops->reoffload(tp, add, cb, cb_priv,
extack);
@@ -1126,6 +1167,7 @@ tcf_block_playback_offloads(struct tcf_block *block,
tc_setup_cb_t *cb,
return 0;
err_playback_remove:
+ tcf_proto_put(tp, NULL);
tcf_chain_put(chain);
tcf_block_playback_offloads(block, cb, cb_priv, false, offload_in_use,
extack);
@@ -1449,8 +1491,8 @@ static void tfilter_notify_chain(struct net *net, struct
sk_buff *oskb,
{
struct tcf_proto *tp;
- for (tp = rtnl_dereference(chain->filter_chain);
- tp; tp = rtnl_dereference(tp->next))
+ for (tp = tcf_get_next_proto(chain, NULL);
+ tp; tp = tcf_get_next_proto(chain, tp))
tfilter_notify(net, oskb, n, tp, block,
q, parent, NULL, event, false);
}
@@ -1875,11 +1917,15 @@ static bool tcf_chain_dump(struct tcf_chain *chain,
struct Qdisc *q, u32 parent,
struct net *net = sock_net(skb->sk);
struct tcf_block *block = chain->block;
struct tcmsg *tcm = nlmsg_data(cb->nlh);
+ struct tcf_proto *tp, *tp_prev;
struct tcf_dump_args arg;
- struct tcf_proto *tp;
- for (tp = rtnl_dereference(chain->filter_chain);
- tp; tp = rtnl_dereference(tp->next), (*p_index)++) {
+ for (tp = __tcf_get_next_proto(chain, NULL);
+ tp;
+ tp_prev = tp,
+ tp = __tcf_get_next_proto(chain, tp),
+ tcf_proto_put(tp_prev, NULL),
+ (*p_index)++) {
if (*p_index < index_start)
continue;
if (TC_H_MAJ(tcm->tcm_info) &&
@@ -1896,7 +1942,7 @@ static bool tcf_chain_dump(struct tcf_chain *chain,
struct Qdisc *q, u32 parent,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, NLM_F_MULTI,
RTM_NEWTFILTER) <= 0)
- return false;
+ goto errout;
cb->args[1] = 1;
}
@@ -1916,9 +1962,13 @@ static bool tcf_chain_dump(struct tcf_chain *chain,
struct Qdisc *q, u32 parent,
cb->args[2] = arg.w.cookie;
cb->args[1] = arg.w.count + 1;
if (arg.w.stop)
- return false;
+ goto errout;
}
return true;
+
+errout:
+ tcf_proto_put(tp, NULL);
+ return false;
}
/* called with RTNL */
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 28e9c3d9981f..0605f01a419b 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1850,8 +1850,8 @@ static void tc_bind_tclass(struct Qdisc *q, u32 portid,
u32 clid,
chain = tcf_get_next_chain(block, chain)) {
struct tcf_proto *tp;
- for (tp = rtnl_dereference(chain->filter_chain);
- tp; tp = rtnl_dereference(tp->next)) {
+ for (tp = tcf_get_next_proto(chain, NULL);
+ tp; tp = tcf_get_next_proto(chain, tp)) {
struct tcf_bind_args arg = {};
arg.w.fn = tcf_node_bind;
--
2.7.5
