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authorVlad Buslov <vladbu@mellanox.com>2019-03-21 15:17:33 +0200
committerDavid S. Miller <davem@davemloft.net>2019-03-21 14:32:17 -0700
commite474619a2498c57f7f0ed8b4abb29d6c62e2393b (patch)
tree25c34d5703e6a1d5c76f9983e982a8aa5bedd83f
parentnfp: remove defines for unused control bits (diff)
downloadlinux-dev-e474619a2498c57f7f0ed8b4abb29d6c62e2393b.tar.xz
linux-dev-e474619a2498c57f7f0ed8b4abb29d6c62e2393b.zip
net: sched: flower: don't check for rtnl on head dereference
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> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/cls_flower.c24
1 files 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 @@ errout_mask_alloc:
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;