As pointed out by Jamal, an action could be shared by
multiple filters, so we can't use list to chain them
any more after we get rid of the original tc_action.
Instead, we could just save pointers to these actions
in tcf_exts, since they are refcount'ed, so convert
the list to an array of pointers.

The "ugly" part is the action API still accepts list
as a parameter, I just introduce a helper function to
convert the array of pointers to a list, instead of
relying on the C99 feature to iterate the array.

Fixes: a85a970af265 ("net_sched: move tc_action into tcf_common")
Reported-by: Jamal Hadi Salim <j...@mojatatu.com>
Cc: Jamal Hadi Salim <j...@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c   |  4 +-
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 12 ++++--
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c  |  4 +-
 include/net/pkt_cls.h                           | 42 +++++++++++++-------
 net/sched/cls_api.c                             | 51 +++++++++++++++++--------
 5 files changed, 79 insertions(+), 34 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 5418c69a..6ac1254 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -8390,12 +8390,14 @@ static int parse_tc_actions(struct ixgbe_adapter 
*adapter,
                            struct tcf_exts *exts, u64 *action, u8 *queue)
 {
        const struct tc_action *a;
+       LIST_HEAD(actions);
        int err;
 
        if (tc_no_actions(exts))
                return -EINVAL;
 
-       tc_for_each_action(a, exts) {
+       tcf_exts_to_list(exts, &actions);
+       list_for_each_entry(a, &actions, list) {
 
                /* Drop action */
                if (is_tcf_gact_shot(a)) {
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c 
b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 0f19b01..dc8b1cb 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -318,6 +318,7 @@ static int parse_tc_nic_actions(struct mlx5e_priv *priv, 
struct tcf_exts *exts,
                                u32 *action, u32 *flow_tag)
 {
        const struct tc_action *a;
+       LIST_HEAD(actions);
 
        if (tc_no_actions(exts))
                return -EINVAL;
@@ -325,7 +326,8 @@ static int parse_tc_nic_actions(struct mlx5e_priv *priv, 
struct tcf_exts *exts,
        *flow_tag = MLX5_FS_DEFAULT_FLOW_TAG;
        *action = 0;
 
-       tc_for_each_action(a, exts) {
+       tcf_exts_to_list(exts, &actions);
+       list_for_each_entry(a, &actions, list) {
                /* Only support a single action per rule */
                if (*action)
                        return -EINVAL;
@@ -362,13 +364,15 @@ static int parse_tc_fdb_actions(struct mlx5e_priv *priv, 
struct tcf_exts *exts,
                                u32 *action, u32 *dest_vport)
 {
        const struct tc_action *a;
+       LIST_HEAD(actions);
 
        if (tc_no_actions(exts))
                return -EINVAL;
 
        *action = 0;
 
-       tc_for_each_action(a, exts) {
+       tcf_exts_to_list(exts, &actions);
+       list_for_each_entry(a, &actions, list) {
                /* Only support a single action per rule */
                if (*action)
                        return -EINVAL;
@@ -503,6 +507,7 @@ int mlx5e_stats_flower(struct mlx5e_priv *priv,
        struct mlx5e_tc_flow *flow;
        struct tc_action *a;
        struct mlx5_fc *counter;
+       LIST_HEAD(actions);
        u64 bytes;
        u64 packets;
        u64 lastuse;
@@ -518,7 +523,8 @@ int mlx5e_stats_flower(struct mlx5e_priv *priv,
 
        mlx5_fc_query_cached(counter, &bytes, &packets, &lastuse);
 
-       tc_for_each_action(a, f->exts)
+       tcf_exts_to_list(f->exts, &actions);
+       list_for_each_entry(a, &actions, list)
                tcf_action_stats_update(a, bytes, packets, lastuse);
 
        return 0;
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c 
b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index e1b8f62..9130cb2 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -1149,6 +1149,7 @@ static int mlxsw_sp_port_add_cls_matchall(struct 
mlxsw_sp_port *mlxsw_sp_port,
                                          bool ingress)
 {
        const struct tc_action *a;
+       LIST_HEAD(actions);
        int err;
 
        if (!tc_single_action(cls->exts)) {
@@ -1156,7 +1157,8 @@ static int mlxsw_sp_port_add_cls_matchall(struct 
mlxsw_sp_port *mlxsw_sp_port,
                return -ENOTSUPP;
        }
 
-       tc_for_each_action(a, cls->exts) {
+       tcf_exts_to_list(cls->exts, &actions);
+       list_for_each_entry(a, &actions, list) {
                if (!is_tcf_mirred_mirror(a) || protocol != htons(ETH_P_ALL))
                        return -ENOTSUPP;
 
diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index 00dd5c4..d882b36 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -59,7 +59,8 @@ tcf_unbind_filter(struct tcf_proto *tp, struct tcf_result *r)
 struct tcf_exts {
 #ifdef CONFIG_NET_CLS_ACT
        __u32   type; /* for backward compat(TCA_OLD_COMPAT) */
-       struct list_head actions;
+       int nr_actions;
+       struct tc_action **actions;
 #endif
        /* Map to export classifier specific extension TLV types to the
         * generic extensions API. Unsupported extensions must be set to 0.
@@ -72,7 +73,10 @@ static inline void tcf_exts_init(struct tcf_exts *exts, int 
action, int police)
 {
 #ifdef CONFIG_NET_CLS_ACT
        exts->type = 0;
-       INIT_LIST_HEAD(&exts->actions);
+       exts->nr_actions = 0;
+       exts->actions = kcalloc(TCA_ACT_MAX_PRIO, sizeof(struct tc_action *),
+                               GFP_KERNEL);
+       WARN_ON(!exts->actions); /* TODO: propagate the error to callers */
 #endif
        exts->action = action;
        exts->police = police;
@@ -89,7 +93,7 @@ static inline int
 tcf_exts_is_predicative(struct tcf_exts *exts)
 {
 #ifdef CONFIG_NET_CLS_ACT
-       return !list_empty(&exts->actions);
+       return exts->nr_actions;
 #else
        return 0;
 #endif
@@ -108,6 +112,20 @@ tcf_exts_is_available(struct tcf_exts *exts)
        return tcf_exts_is_predicative(exts);
 }
 
+static inline void
+tcf_exts_to_list(const struct tcf_exts *exts, struct list_head *actions)
+{
+#ifdef CONFIG_NET_CLS_ACT
+       int i;
+
+       for (i = 0; i < exts->nr_actions; i++) {
+               struct tc_action *a = exts->actions[i];
+
+               list_add(&a->list, actions);
+       }
+#endif
+}
+
 /**
  * tcf_exts_exec - execute tc filter extensions
  * @skb: socket buffer
@@ -124,27 +142,23 @@ tcf_exts_exec(struct sk_buff *skb, struct tcf_exts *exts,
               struct tcf_result *res)
 {
 #ifdef CONFIG_NET_CLS_ACT
-       if (!list_empty(&exts->actions))
-               return tcf_action_exec(skb, &exts->actions, res);
+       LIST_HEAD(actions);
+
+       tcf_exts_to_list(exts, &actions);
+       if (exts->nr_actions)
+               return tcf_action_exec(skb, &actions, res);
 #endif
        return 0;
 }
 
 #ifdef CONFIG_NET_CLS_ACT
 
-#define tc_no_actions(_exts) \
-       (list_empty(&(_exts)->actions))
-
-#define tc_for_each_action(_a, _exts) \
-       list_for_each_entry(_a, &(_exts)->actions, list)
-
-#define tc_single_action(_exts) \
-       (list_is_singular(&(_exts)->actions))
+#define tc_no_actions(_exts)  ((_exts)->nr_actions == 0)
+#define tc_single_action(_exts) ((_exts)->nr_actions == 1)
 
 #else /* CONFIG_NET_CLS_ACT */
 
 #define tc_no_actions(_exts) true
-#define tc_for_each_action(_a, _exts) while ((void)(_a), 0)
 #define tc_single_action(_exts) false
 
 #endif /* CONFIG_NET_CLS_ACT */
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 843a716..a7c5645 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -541,8 +541,12 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct 
netlink_callback *cb)
 void tcf_exts_destroy(struct tcf_exts *exts)
 {
 #ifdef CONFIG_NET_CLS_ACT
-       tcf_action_destroy(&exts->actions, TCA_ACT_UNBIND);
-       INIT_LIST_HEAD(&exts->actions);
+       LIST_HEAD(actions);
+
+       tcf_exts_to_list(exts, &actions);
+       tcf_action_destroy(&actions, TCA_ACT_UNBIND);
+       kfree(exts->actions);
+       exts->nr_actions = 0;
 #endif
 }
 EXPORT_SYMBOL(tcf_exts_destroy);
@@ -554,7 +558,6 @@ int tcf_exts_validate(struct net *net, struct tcf_proto 
*tp, struct nlattr **tb,
        {
                struct tc_action *act;
 
-               INIT_LIST_HEAD(&exts->actions);
                if (exts->police && tb[exts->police]) {
                        act = tcf_action_init_1(net, tb[exts->police], rate_tlv,
                                                "police", ovr,
@@ -563,14 +566,20 @@ int tcf_exts_validate(struct net *net, struct tcf_proto 
*tp, struct nlattr **tb,
                                return PTR_ERR(act);
 
                        act->type = exts->type = TCA_OLD_COMPAT;
-                       list_add(&act->list, &exts->actions);
+                       exts->actions[0] = act;
+                       exts->nr_actions = 1;
                } else if (exts->action && tb[exts->action]) {
-                       int err;
+                       LIST_HEAD(actions);
+                       int err, i = 0;
+
                        err = tcf_action_init(net, tb[exts->action], rate_tlv,
                                              NULL, ovr,
-                                             TCA_ACT_BIND, &exts->actions);
+                                             TCA_ACT_BIND, &actions);
                        if (err)
                                return err;
+                       list_for_each_entry(act, &actions, list)
+                               exts->actions[i++] = act;
+                       exts->nr_actions = i;
                }
        }
 #else
@@ -587,37 +596,49 @@ void tcf_exts_change(struct tcf_proto *tp, struct 
tcf_exts *dst,
                     struct tcf_exts *src)
 {
 #ifdef CONFIG_NET_CLS_ACT
-       LIST_HEAD(tmp);
+       struct tcf_exts old = *dst;
+
        tcf_tree_lock(tp);
-       list_splice_init(&dst->actions, &tmp);
-       list_splice(&src->actions, &dst->actions);
+       dst->nr_actions = src->nr_actions;
+       dst->actions = src->actions;
        dst->type = src->type;
        tcf_tree_unlock(tp);
-       tcf_action_destroy(&tmp, TCA_ACT_UNBIND);
+
+       tcf_exts_destroy(&old);
 #endif
 }
 EXPORT_SYMBOL(tcf_exts_change);
 
-#define tcf_exts_first_act(ext)                                        \
-       list_first_entry_or_null(&(exts)->actions,              \
-                                struct tc_action, list)
+#ifdef CONFIG_NET_CLS_ACT
+static struct tc_action *tcf_exts_first_act(struct tcf_exts *exts)
+{
+       if (exts->nr_actions == 0)
+               return NULL;
+       else
+               return exts->actions[0];
+}
+#endif
 
 int tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts)
 {
 #ifdef CONFIG_NET_CLS_ACT
        struct nlattr *nest;
 
-       if (exts->action && !list_empty(&exts->actions)) {
+       if (exts->action && exts->nr_actions) {
                /*
                 * again for backward compatible mode - we want
                 * to work with both old and new modes of entering
                 * tc data even if iproute2  was newer - jhs
                 */
                if (exts->type != TCA_OLD_COMPAT) {
+                       LIST_HEAD(actions);
+
                        nest = nla_nest_start(skb, exts->action);
                        if (nest == NULL)
                                goto nla_put_failure;
-                       if (tcf_action_dump(skb, &exts->actions, 0, 0) < 0)
+
+                       tcf_exts_to_list(exts, &actions);
+                       if (tcf_action_dump(skb, &actions, 0, 0) < 0)
                                goto nla_put_failure;
                        nla_nest_end(skb, nest);
                } else if (exts->police) {
-- 
2.1.0

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