From: Vlad Buslov <vladbu@mellanox.com>
To: netdev@vger.kernel.org
Cc: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us,
davem@davemloft.net, sbrivio@redhat.com,
Vlad Buslov <vladbu@mellanox.com>
Subject: [PATCH net-next v3 01/12] net: sched: flower: don't check for rtnl on head dereference
Date: Thu, 21 Mar 2019 15:17:33 +0200 [thread overview]
Message-ID: <20190321131744.19224-2-vladbu@mellanox.com> (raw)
In-Reply-To: <20190321131744.19224-1-vladbu@mellanox.com>
Flower classifier only changes root pointer during init and destroy. Cls
API implements reference counting for tcf_proto, so there is no danger of
concurrent access to tp when it is being destroyed, even without protection
provided by rtnl lock.
Implement new function fl_head_dereference() to dereference tp->root
without checking for rtnl lock. Use it in all flower function that obtain
head pointer instead of rtnl_dereference().
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
---
net/sched/cls_flower.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index c04247b403ed..dcf3aee5697e 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -437,10 +437,20 @@ static void fl_hw_update_stats(struct tcf_proto *tp, struct cls_fl_filter *f)
cls_flower.stats.lastused);
}
+static struct cls_fl_head *fl_head_dereference(struct tcf_proto *tp)
+{
+ /* Flower classifier only changes root pointer during init and destroy.
+ * Users must obtain reference to tcf_proto instance before calling its
+ * API, so tp->root pointer is protected from concurrent call to
+ * fl_destroy() by reference counting.
+ */
+ return rcu_dereference_raw(tp->root);
+}
+
static bool __fl_delete(struct tcf_proto *tp, struct cls_fl_filter *f,
struct netlink_ext_ack *extack)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
bool async = tcf_exts_get_net(&f->exts);
bool last;
@@ -472,7 +482,7 @@ static void fl_destroy_sleepable(struct work_struct *work)
static void fl_destroy(struct tcf_proto *tp, bool rtnl_held,
struct netlink_ext_ack *extack)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
struct fl_flow_mask *mask, *next_mask;
struct cls_fl_filter *f, *next;
@@ -490,7 +500,7 @@ static void fl_destroy(struct tcf_proto *tp, bool rtnl_held,
static void *fl_get(struct tcf_proto *tp, u32 handle)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
return idr_find(&head->handle_idr, handle);
}
@@ -1308,7 +1318,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
void **arg, bool ovr, bool rtnl_held,
struct netlink_ext_ack *extack)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
struct cls_fl_filter *fold = *arg;
struct cls_fl_filter *fnew;
struct fl_flow_mask *mask;
@@ -1446,7 +1456,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
static int fl_delete(struct tcf_proto *tp, void *arg, bool *last,
bool rtnl_held, struct netlink_ext_ack *extack)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
struct cls_fl_filter *f = arg;
rhashtable_remove_fast(&f->mask->ht, &f->ht_node,
@@ -1459,7 +1469,7 @@ static int fl_delete(struct tcf_proto *tp, void *arg, bool *last,
static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg,
bool rtnl_held)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
struct cls_fl_filter *f;
arg->count = arg->skip;
@@ -1478,7 +1488,7 @@ static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg,
static int fl_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
void *cb_priv, struct netlink_ext_ack *extack)
{
- struct cls_fl_head *head = rtnl_dereference(tp->root);
+ struct cls_fl_head *head = fl_head_dereference(tp);
struct tc_cls_flower_offload cls_flower = {};
struct tcf_block *block = tp->chain->block;
struct fl_flow_mask *mask;
--
2.21.0
next prev parent reply other threads:[~2019-03-21 13:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 13:17 [PATCH net-next v3 00/12] Refactor flower classifier to remove dependency on rtnl lock Vlad Buslov
2019-03-21 13:17 ` Vlad Buslov [this message]
2019-03-21 13:51 ` [PATCH net-next v3 01/12] net: sched: flower: don't check for rtnl on head dereference Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 02/12] net: sched: flower: refactor fl_change Vlad Buslov
2019-03-21 13:53 ` Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 03/12] net: sched: flower: introduce reference counting for filters Vlad Buslov
2019-03-21 14:00 ` Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 04/12] net: sched: flower: track filter deletion with flag Vlad Buslov
2019-03-21 14:04 ` Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 05/12] net: sched: flower: add reference counter to flower mask Vlad Buslov
2019-03-21 13:17 ` [PATCH net-next v3 06/12] net: sched: flower: handle concurrent mask insertion Vlad Buslov
2019-03-21 13:17 ` [PATCH net-next v3 07/12] net: sched: flower: protect masks list with spinlock Vlad Buslov
2019-03-21 13:17 ` [PATCH net-next v3 08/12] net: sched: flower: handle concurrent filter insertion in fl_change Vlad Buslov
2019-03-21 13:17 ` [PATCH net-next v3 09/12] net: sched: flower: handle concurrent tcf proto deletion Vlad Buslov
2019-03-21 14:06 ` Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 10/12] net: sched: flower: protect flower classifier state with spinlock Vlad Buslov
2019-03-21 14:09 ` Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 11/12] net: sched: flower: track rtnl lock state Vlad Buslov
2019-03-21 14:11 ` Jiri Pirko
2019-03-21 13:17 ` [PATCH net-next v3 12/12] net: sched: flower: set unlocked flag for flower proto ops Vlad Buslov
2019-03-21 14:13 ` Jiri Pirko
2019-03-21 21:33 ` [PATCH net-next v3 00/12] Refactor flower classifier to remove dependency on rtnl lock David Miller
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