Consider an skb which doesn't match a ptype_base/ptype_specific handler. If
this skb is delivered to a ptype_all handler, it does not count as a drop.
However, if the skb is also processed by an rx_handler which returns
RX_HANDLER_PASS, the frame is now counted as a drop because pt_prev was
reset. An example of this situation is an LLDP frame received on a bridge
port while lldpd is listening on a packet socket with ETH_P_ALL (ex. by
specifying `lldpd -c`).
Fix by adding an extra condition variable to record if the skb was
delivered to a packet tap before running an rx_handler.
The situation is similar for RX_HANDLER_EXACT frames so their accounting is
also changed. OTOH, the behavior is unchanged for RX_HANDLER_ANOTHER frames
- they are accounted according to what happens with the new skb->dev.
Fixes: caf586e5f23c ("net: add a core netdev->rx_dropped counter")
Message-Id: <20200522011420.263574-1-bpoir...@cumulusnetworks.com>
Signed-off-by: Benjamin Poirier <bpoir...@cumulusnetworks.com>
---
net/core/dev.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index ae37586f6ee8..07957a0f57e6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5061,11 +5061,11 @@ static inline int nf_ingress(struct sk_buff *skb,
struct packet_type **pt_prev,
static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
struct packet_type **ppt_prev)
{
+ bool deliver_exact = false, rx_tapped = false;
struct packet_type *ptype, *pt_prev;
rx_handler_func_t *rx_handler;
struct sk_buff *skb = *pskb;
struct net_device *orig_dev;
- bool deliver_exact = false;
int ret = NET_RX_DROP;
__be16 type;
@@ -5158,12 +5158,14 @@ static int __netif_receive_skb_core(struct sk_buff
**pskb, bool pfmemalloc,
if (pt_prev) {
ret = deliver_skb(skb, pt_prev, orig_dev);
pt_prev = NULL;
+ rx_tapped = true;
}
switch (rx_handler(&skb)) {
case RX_HANDLER_CONSUMED:
ret = NET_RX_SUCCESS;
goto out;
case RX_HANDLER_ANOTHER:
+ rx_tapped = false;
goto another_round;
case RX_HANDLER_EXACT:
deliver_exact = true;
@@ -5234,11 +5236,13 @@ static int __netif_receive_skb_core(struct sk_buff
**pskb, bool pfmemalloc,
goto drop;
*ppt_prev = pt_prev;
} else {
+ if (!rx_tapped) {
drop:
- if (!deliver_exact)
- atomic_long_inc(&skb->dev->rx_dropped);
- else
- atomic_long_inc(&skb->dev->rx_nohandler);
+ if (!deliver_exact)
+ atomic_long_inc(&skb->dev->rx_dropped);
+ else
+ atomic_long_inc(&skb->dev->rx_nohandler);
+ }
kfree_skb(skb);
/* Jamal, now you will not able to escape explaining
* me how you were going to use this. :-)
--
2.26.2
