[PATCH] mpls: defer ttl decrement in mpls_forward()

From: Kangmin Park
Date: Thu Jul 22 2021 - 14:50:39 EST


Defer ttl decrement to optimize in tx_err case. There is no need
to decrease ttl in the case of goto tx_err.

Signed-off-by: Kangmin Park <l4stpr0gr4m@xxxxxxxxx>
---
net/mpls/af_mpls.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 05a21dd072df..ffeb2df8be7a 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -407,7 +407,6 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
/* Verify ttl is valid */
if (dec.ttl <= 1)
goto err;
- dec.ttl -= 1;

/* Find the output device */
out_dev = rcu_dereference(nh->nh_dev);
@@ -431,6 +430,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
skb->dev = out_dev;
skb->protocol = htons(ETH_P_MPLS_UC);

+ dec.ttl -= 1;
if (unlikely(!new_header_size && dec.bos)) {
/* Penultimate hop popping */
if (!mpls_egress(dev_net(out_dev), rt, skb, dec))
--
2.26.2