When a CAN node reaches BUS-OFF state, its netdev state
is set to __LINK_STATE_NOCARRIER and qdisc ->enqueue() starts
dropping frames and returning NET_XMIT_CN that is turned to 0
by net_xmit_errno(). So can_send() returns success to a sender
even if his frame is lost.
As this behavior is inappropriate for a node in BUS-OFF state,
this patch adds a check for no-carrier condition and returns
-ENETUNREACH in such case.
Signed-off-by: Jaroslav Beran <jara.beran@xxxxxxxxx>
---
net/can/af_can.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 5518a7d9eed9..68c56241733b 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -189,6 +189,7 @@ static int can_create(struct net *net, struct socket *sock, int protocol,
* Return:
* 0 on success
* -ENETDOWN when the selected interface is down
+ * -ENETUNREACH when the node is in BUS-OFF state
* -ENOBUFS on full driver queue (see net_xmit_errno())
* -ENOMEM when local loopback failed at calling skb_clone()
* -EPERM when trying to send on a non-CAN interface
@@ -233,6 +234,11 @@ int can_send(struct sk_buff *skb, int loop)
goto inval_skb;
}
+ if (unlikely(!netif_carrier_ok(skb->dev))) {
+ err = -ENETUNREACH;
+ goto inval_skb;
+ }
+
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb_reset_mac_header(skb);
--
2.23.0
