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net: sched: traverse classifiers in chain with tcf_get_next_proto() 

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 <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Buslov 2019-02-11 10:55:40 +02:00 committed by David S. Miller
parent 4dbfa76644
commit fe2923afc1
3 changed files with 64 additions and 12 deletions
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2
include/net/pkt_cls.h
View File

@ -46,6 +46,8 @@ 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,

70
net/sched/cls_api.c
View File

@ -980,6 +980,45 @@ 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();
mutex_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);
mutex_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;
@ -1352,7 +1391,7 @@ 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);
@ -1360,8 +1399,10 @@ 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);
@ -1378,6 +1419,7 @@ 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);
@ -1677,8 +1719,8 @@ 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);
}
@ -2104,11 +2146,15 @@ 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) &&
@ -2125,7 +2171,7 @@ 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;
}
@ -2145,9 +2191,13 @@ 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 */

4
net/sched/sch_api.c
View File

@ -1914,8 +1914,8 @@ 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;