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net: sched: introduce reference counting for tcf_proto 

In order to remove dependency on rtnl lock and allow concurrent tcf_proto
modification, extend tcf_proto with reference counter. Implement helper
get/put functions for tcf proto and use them to modify cls API to always
take reference to tcf_proto while using it. Only release reference to
parent chain after releasing last reference to tp.

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 10:55:39 +02:00 committed by David S. Miller
parent ed76f5edcc
commit 4dbfa76644
2 changed files with 44 additions and 10 deletions
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1
include/net/sch_generic.h
View File

@ -322,6 +322,7 @@ struct tcf_proto {
void *data;
const struct tcf_proto_ops *ops;
struct tcf_chain *chain;
refcount_t refcnt;
struct rcu_head rcu;
};

53
net/sched/cls_api.c
View File

@ -180,6 +180,7 @@ static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol,
tp->protocol = protocol;
tp->prio = prio;
tp->chain = chain;
refcount_set(&tp->refcnt, 1);
err = tp->ops->init(tp);
if (err) {
@ -193,14 +194,29 @@ errout:
return ERR_PTR(err);
}
static void tcf_proto_get(struct tcf_proto *tp)
{
refcount_inc(&tp->refcnt);
}
static void tcf_chain_put(struct tcf_chain *chain);
static void tcf_proto_destroy(struct tcf_proto *tp,
struct netlink_ext_ack *extack)
{
tp->ops->destroy(tp, extack);
tcf_chain_put(tp->chain);
module_put(tp->ops->owner);
kfree_rcu(tp, rcu);
}
static void tcf_proto_put(struct tcf_proto *tp,
struct netlink_ext_ack *extack)
{
if (refcount_dec_and_test(&tp->refcnt))
tcf_proto_destroy(tp, extack);
}
#define ASSERT_BLOCK_LOCKED(block) \
lockdep_assert_held(&(block)->lock)
@ -445,18 +461,18 @@ static void tcf_chain_put_explicitly_created(struct tcf_chain *chain)
static void tcf_chain_flush(struct tcf_chain *chain)
{
struct tcf_proto *tp;
struct tcf_proto *tp, *tp_next;
mutex_lock(&chain->filter_chain_lock);
tp = tcf_chain_dereference(chain->filter_chain, chain);
RCU_INIT_POINTER(chain->filter_chain, NULL);
tcf_chain0_head_change(chain, NULL);
mutex_unlock(&chain->filter_chain_lock);
while (tp) {
RCU_INIT_POINTER(chain->filter_chain, tp->next);
tcf_proto_destroy(tp, NULL);
tp = rtnl_dereference(chain->filter_chain);
tcf_chain_put(chain);
tp_next = rcu_dereference_protected(tp->next, 1);
tcf_proto_put(tp, NULL);
tp = tp_next;
}
}
@ -1500,9 +1516,9 @@ static void tcf_chain_tp_insert(struct tcf_chain *chain,
{
if (*chain_info->pprev == chain->filter_chain)
tcf_chain0_head_change(chain, tp);
tcf_proto_get(tp);
RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain, chain_info));
rcu_assign_pointer(*chain_info->pprev, tp);
tcf_chain_hold(chain);
}
static void tcf_chain_tp_remove(struct tcf_chain *chain,
@ -1514,7 +1530,6 @@ static void tcf_chain_tp_remove(struct tcf_chain *chain,
if (tp == chain->filter_chain)
tcf_chain0_head_change(chain, next);
RCU_INIT_POINTER(*chain_info->pprev, next);
tcf_chain_put(chain);
}
static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
@ -1541,7 +1556,12 @@ static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
}
}
chain_info->pprev = pprev;
chain_info->next = tp ? tp->next : NULL;
if (tp) {
chain_info->next = tp->next;
tcf_proto_get(tp);
} else {
chain_info->next = NULL;
}
return tp;
}
@ -1699,6 +1719,7 @@ replay:
prio = TC_H_MAJ(t->tcm_info);
prio_allocate = false;
parent = t->tcm_parent;
tp = NULL;
cl = 0;
if (prio == 0) {
@ -1816,6 +1837,12 @@ replay:
errout:
if (chain)
tcf_chain_put(chain);
if (chain) {
if (tp && !IS_ERR(tp))
tcf_proto_put(tp, NULL);
if (!tp_created)
tcf_chain_put(chain);
}
tcf_block_release(q, block);
if (err == -EAGAIN)
/* Replay the request. */
@ -1946,8 +1973,11 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
}
errout:
if (chain)
if (chain) {
if (tp && !IS_ERR(tp))
tcf_proto_put(tp, NULL);
tcf_chain_put(chain);
}
tcf_block_release(q, block);
return err;
@ -2038,8 +2068,11 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
}
errout:
if (chain)
if (chain) {
if (tp && !IS_ERR(tp))
tcf_proto_put(tp, NULL);
tcf_chain_put(chain);
}
tcf_block_release(q, block);
return err;
}