netdev - [RESEND PATCH net-next 3/4] net: sched: refactor ct action helpers to require tcf

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Date:   Mon, 17 Feb 2020 12:12:11 +0200
From:   Vlad Buslov <vladbu@...lanox.com>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        pablo@...filter.org, marcelo.leitner@...il.com,
        Vlad Buslov <vladbu@...lanox.com>,
        Jiri Pirko <jiri@...lanox.com>
Subject: [RESEND PATCH net-next 3/4] net: sched: refactor ct action helpers to require tcf_lock

In order to remove rtnl lock dependency from flow_action representation
translator, change rtnl_dereference() to rcu_dereference_protected() in ct
action helpers that provide external access to zone and action values. This
is safe to do because the functions are not called from anywhere else
outside flow_action infrastructure which was modified to obtain tcf_lock
when accessing action data in one of previous patches in the series.

Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
Acked-by: Jiri Pirko <jiri@...lanox.com>
---
 include/net/tc_act/tc_ct.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/net/tc_act/tc_ct.h b/include/net/tc_act/tc_ct.h
index bdc20ab3b88d..a8b156402873 100644
--- a/include/net/tc_act/tc_ct.h
+++ b/include/net/tc_act/tc_ct.h
@@ -33,8 +33,10 @@ struct tcf_ct {
 };
 
 #define to_ct(a) ((struct tcf_ct *)a)
-#define to_ct_params(a) ((struct tcf_ct_params *) \
-			 rtnl_dereference((to_ct(a)->params)))
+#define to_ct_params(a)							\
+	((struct tcf_ct_params *)					\
+	 rcu_dereference_protected(to_ct(a)->params,			\
+				   lockdep_is_held(&a->tcfa_lock)))
 
 static inline uint16_t tcf_ct_zone(const struct tc_action *a)
 {
-- 
2.21.0