From af1cc7a2b86ddb8668ac38097866bedd7b849a76 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 30 Nov 2016 13:17:51 +0800 Subject: [PATCH] tun: handle ubuf refcount correctly when meet errors We trigger uarg->callback() immediately after we decide do datacopy even if caller want to do zerocopy. This will cause the callback (vhost_net_zerocopy_callback) decrease the refcount. But when we meet an error afterwards, the error handling in vhost handle_tx() will try to decrease it again. This is wrong and fix this by delay the uarg->callback() until we're sure there's no errors. Reported-by: wangyunjian Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/net/tun.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 8093e39ae263..db6acecabeaa 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1246,13 +1246,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (zerocopy) err = zerocopy_sg_from_iter(skb, from); - else { + else err = skb_copy_datagram_from_iter(skb, 0, from, len); - if (!err && msg_control) { - struct ubuf_info *uarg = msg_control; - uarg->callback(uarg, false); - } - } if (err) { this_cpu_inc(tun->pcpu_stats->rx_dropped); @@ -1298,6 +1293,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, skb_shinfo(skb)->destructor_arg = msg_control; skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; + } else if (msg_control) { + struct ubuf_info *uarg = msg_control; + uarg->callback(uarg, false); } skb_reset_network_header(skb); -- 2.30.2