From: Willem de Bruijn <willemb@google.com>
Date: Tue, 5 Dec 2017 22:11:17 -0500
Subject: tun: avoid unnecessary READ_ONCE in tun_net_xmit
Patch-mainline: v4.16-rc1
Git-commit: cc166427dcdab39a96140fded18ac23be5f0a1ed
References: bsc#1109837
The statement no longer serves a purpose.
Commit fa35864e0bb7 ("tuntap: Fix for a race in accessing numqueues")
added the ACCESS_ONCE to avoid a race condition with skb_queue_len.
Commit 436accebb530 ("tuntap: remove unnecessary sk_receive_queue
length check during xmit") removed the affected skb_queue_len check.
Commit 96f84061620c ("tun: add eBPF based queue selection method")
split the function, reading the field a second time in the callee.
The temp variable is now only read once, so just remove it.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/net/tun.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -999,14 +999,12 @@ static netdev_tx_t tun_net_xmit(struct s
struct tun_struct *tun = netdev_priv(dev);
int txq = skb->queue_mapping;
struct tun_file *tfile;
- u32 numqueues = 0;
rcu_read_lock();
tfile = rcu_dereference(tun->tfiles[txq]);
- numqueues = READ_ONCE(tun->numqueues);
/* Drop packet if interface is not attached */
- if (txq >= numqueues)
+ if (txq >= tun->numqueues)
goto drop;
if (!rcu_dereference(tun->steering_prog))