netdev - [PATCH bpf-next] lwt_bpf: remove unnecessary rcu_read_lock in run_lwt

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Message-Id: <20180730132259.6338-1-ap420073@gmail.com>
Date:   Mon, 30 Jul 2018 22:22:59 +0900
From:   Taehee Yoo <ap420073@...il.com>
To:     daniel@...earbox.net, ast@...nel.org
Cc:     netdev@...r.kernel.org, ap420073@...il.com
Subject: [PATCH bpf-next] lwt_bpf: remove unnecessary rcu_read_lock in run_lwt_bpf

run_lwt_bpf is called by bpf_{input/output/xmit}.
These functions are already protected by rcu_read_lock.
because lwtunnel_{input/output/xmit} holds rcu_read_lock
and then calls bpf_{input/output/xmit}.
So that rcu_read_lock in the run_lwt_bpf is unnecessary.

Signed-off-by: Taehee Yoo <ap420073@...il.com>
---
 net/core/lwt_bpf.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index e7e626f..a49c7ba 100644
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -50,10 +50,8 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
 	 * mixing with BH RCU lock doesn't work.
 	 */
 	preempt_disable();
-	rcu_read_lock();
 	bpf_compute_data_pointers(skb);
 	ret = bpf_prog_run_save_cb(lwt->prog, skb);
-	rcu_read_unlock();
 
 	switch (ret) {
 	case BPF_OK:
-- 
2.9.3