[net-next PATCH 3/9] bpf: sockmap add missing rcu_read_(un)lock in smap_data_ready

[John Fastabend]

References to psock must be done inside RCU critical section.

Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
Signed-off-by: John Fastabend <john.fastab...@gmail.com>
---
 kernel/bpf/sockmap.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index a6882e5..266011c8 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -227,11 +227,14 @@ static void smap_data_ready(struct sock *sk)
 {
        struct smap_psock *psock;
 
-       write_lock_bh(&sk->sk_callback_lock);
+       rcu_read_lock();
        psock = smap_psock_sk(sk);
-       if (likely(psock))
+       if (likely(psock)) {
+               write_lock_bh(&sk->sk_callback_lock);
                strp_data_ready(&psock->strp);
-       write_unlock_bh(&sk->sk_callback_lock);
+               write_unlock_bh(&sk->sk_callback_lock);
+       }
+       rcu_read_unlock();
 }
 
 static void smap_tx_work(struct work_struct *w)