From: Taehee Yoo <ap420073@gmail.com>
Date: Mon, 30 Jul 2018 13:22:59 +0000 (+0900)
Subject: lwt_bpf: remove unnecessary rcu_read_lock in run_lwt_bpf
X-Git-Tag: for-linus-20180825~89^2~108^2~10
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=1f821611f49a89d2258d256efedd618eda6344be;p=linux-block.git

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@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---

diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index e7e626fb87bb..a49c7baf62f8 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: