[PATCH net-next v4] packet: uses kfree_skb() for errors.

[PATCH net-next v4] packet: uses kfree_skb() for errors.

[Weongyo Jeong]

consume_skb() isn't for error cases that kfree_skb() is more proper
one.  At this patch, it fixed tpacket_rcv() and packet_rcv() to be
consistent for error or non-error cases letting perf trace its event
properly.

Signed-off-by: Weongyo Jeong <weongyo.linux@gmail.com>
---
 net/packet/af_packet.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 1ecfa71..3df29df 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2042,6 +2042,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 	u8 *skb_head = skb->data;
 	int skb_len = skb->len;
 	unsigned int snaplen, res;
+	bool is_drop_n_account = false;
 
 	if (skb->pkt_type == PACKET_LOOPBACK)
 		goto drop;
@@ -2130,6 +2131,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 	return 0;
 
 drop_n_acct:
+	is_drop_n_account = true;
 	spin_lock(&sk->sk_receive_queue.lock);
 	po->stats.stats1.tp_drops++;
 	atomic_inc(&sk->sk_drops);
@@ -2141,7 +2143,10 @@ drop_n_restore:
 		skb->len = skb_len;
 	}
 drop:
-	consume_skb(skb);
+	if (!is_drop_n_account)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
 	return 0;
 }
 
@@ -2160,6 +2165,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	struct sk_buff *copy_skb = NULL;
 	struct timespec ts;
 	__u32 ts_status;
+	bool is_drop_n_account = false;
 
 	/* struct tpacket{2,3}_hdr is aligned to a multiple of TPACKET_ALIGNMENT.
 	 * We may add members to them until current aligned size without forcing
@@ -2367,10 +2373,14 @@ drop_n_restore:
 		skb->len = skb_len;
 	}
 drop:
-	kfree_skb(skb);
+	if (!is_drop_n_account)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
 	return 0;
 
 drop_n_account:
+	is_drop_n_account = true;
 	po->stats.stats1.tp_drops++;
 	spin_unlock(&sk->sk_receive_queue.lock);
 
-- 
2.1.3

Re: [PATCH net-next v4] packet: uses kfree_skb() for errors.

[David Miller]

From: Weongyo Jeong <weongyo.linux@gmail.com>
Date: Thu, 14 Apr 2016 14:10:04 -0700

> consume_skb() isn't for error cases that kfree_skb() is more proper
> one.  At this patch, it fixed tpacket_rcv() and packet_rcv() to be
> consistent for error or non-error cases letting perf trace its event
> properly.
> 
> Signed-off-by: Weongyo Jeong <weongyo.linux@gmail.com>

Applied, thanks.