net/sched: act_csum: don't use spinlock in the fast path

use RCU instead of spin_{,unlock}_bh() to protect concurrent read/write on
act_csum configuration, to reduce the effects of contention in the data
path when multiple readers are present.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 2 deletions

diff --git a/include/net/tc_act/tc_csum.h b/include/net/tc_act/tc_csum.h
index 781f3433a0be..9470fd7e4350 100644
--- a/include/net/tc_act/tc_csum.h
+++ b/include/net/tc_act/tc_csum.h
@@ -6,10 +6,16 @@
 #include <net/act_api.h>
 #include <linux/tc_act/tc_csum.h>
 
+struct tcf_csum_params {
+	int action;
+	u32 update_flags;
+	struct rcu_head rcu;
+};
+
 struct tcf_csum {
 	struct tc_action common;
 
-	u32 update_flags;
+	struct tcf_csum_params __rcu *params;
 };
 #define to_tcf_csum(a) ((struct tcf_csum *)a)
 
@@ -24,7 +30,13 @@ static inline bool is_tcf_csum(const struct tc_action *a)
 
 static inline u32 tcf_csum_update_flags(const struct tc_action *a)
 {
-	return to_tcf_csum(a)->update_flags;
+	u32 update_flags;
+
+	rcu_read_lock();
+	update_flags = rcu_dereference(to_tcf_csum(a)->params)->update_flags;
+	rcu_read_unlock();
+
+	return update_flags;
 }
 
 #endif /* __NET_TC_CSUM_H */