[PATCH net-next V2 04/11] tuntap: simplify error handling in tun_build_skb()

Jason Wang
2018-09-12T03:17:02Z

There's no need to duplicate page get logic in each action. So this
patch tries to get page and calculate the offset before processing XDP
actions (except for XDP_DROP), and undo them when meet errors (we
don't care the performance on errors). This will be used for factoring
out XDP logic.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/net/tun.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 372caf7d67d9..257cf7342d54 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1701,17 +1701,13 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
xdp_do_flush_map();
if (err)
goto err_redirect;
- rcu_read_unlock();
- local_bh_enable();
- return NULL;
+ goto out;
case XDP_TX:
get_page(alloc_frag->page);
alloc_frag->offset += buflen;
if (tun_xdp_tx(tun->dev, &xdp) < 0)
goto err_redirect;
- rcu_read_unlock();
- local_bh_enable();
- return NULL;
+ goto out;
case XDP_PASS:
delta = orig_data - xdp.data;
len = xdp.data_end - xdp.data;
@@ -1742,7 +1738,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,

err_redirect:
put_page(alloc_frag->page);
-err_xdp:
+out:
rcu_read_unlock();
local_bh_enable();
this_cpu_inc(tun->pcpu_stats->rx_dropped);
--
2.17.1