can: fix NOHZ local_softirq_pending 08 warning

When using nanosleep() in an userspace application we get a ratelimit warning

NOHZ: local_softirq_pending 08

for 10 times.

The echo of CAN frames is done from process context and softirq context only.
Therefore the usage of netif_rx() was wrong (for years).

This patch replaces netif_rx() with netif_rx_ni() which has to be used from
process/softirq context. It also adds a missing comment that can_send() must
no be used from hardirq context.

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: Urs Thuermann <urs@isnogud.escape.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/can/af_can.c b/net/can/af_can.c
index ef1c43a2ed56..606832115674 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -199,6 +199,8 @@ static int can_create(struct net *net, struct socket *sock, int protocol)
  * @skb: pointer to socket buffer with CAN frame in data section
  * @loop: loopback for listeners on local CAN sockets (recommended default!)
  *
+ * Due to the loopback this routine must not be called from hardirq context.
+ *
  * Return:
  *  0 on success
  *  -ENETDOWN when the selected interface is down
@@ -278,7 +280,7 @@ int can_send(struct sk_buff *skb, int loop)
         }
 
         if (newskb)
-                netif_rx(newskb);
+                netif_rx_ni(newskb);
 
         /* update statistics */
         can_stats.tx_frames++;