From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wang Jian Subject: [PATCH 1/1] tap: comment fix Date: Thu, 16 Aug 2018 21:01:27 +0800 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" To: "David S . Miller" , Jason , girish.moodalbail@oracle.com, mst@redhat.com, Willem de Bruijn , viro@zeniv.linux.org.uk, wexu@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The tap_queue and the "tap_dev" are loosely coupled, not "macvlan_dev". And I also change one rcu_read_lock's place, seems can reduce rcu critical section a little. Signed-off-by: Wang Jian --- drivers/net/tap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index f0f7cd9..e5e5a8e 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -125,7 +125,7 @@ static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev) /* * RCU usage: - * The tap_queue and the macvlan_dev are loosely coupled, the + * The tap_queue and the tap_dev are loosely coupled, the * pointers from one to the other can only be read while rcu_read_lock * or rtnl is held. * @@ -720,8 +720,6 @@ static ssize_t tap_get_user(struct tap_queue *q, struct msghdr *m, __vlan_get_protocol(skb, skb->protocol, &depth) != 0) skb_set_network_header(skb, depth); - rcu_read_lock(); - tap = rcu_dereference(q->tap); /* copy skb_ubuf_info for callback when skb has no error */ if (zerocopy) { skb_shinfo(skb)->destructor_arg = m->msg_control; @@ -732,6 +730,8 @@ static ssize_t tap_get_user(struct tap_queue *q, struct msghdr *m, uarg->callback(uarg, false); } + rcu_read_lock(); + tap = rcu_dereference(q->tap); if (tap) { skb->dev = tap->dev; dev_queue_xmit(skb); -- Regards, Wang Jian