can: fix NOHZ local_softirq_pending 08 warning

commit 481a8199142c050b72bff8a1956a49fd0a75bbe0 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/net/can/vcan.c b/drivers/net/can/vcan.c
index a10c1d7b3b0a6383a0fd255d1132dfabe49cbeca..460bb886fbdfb8509d1afa2c3f12a638d9e170cf 100644 (file)
--- a/drivers/net/can/vcan.c
+++ b/drivers/net/can/vcan.c
@@ -80,7 +80,7 @@ static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
        skb->dev       = dev;
        skb->ip_summed = CHECKSUM_UNNECESSARY;
 
-       netif_rx(skb);
+       netif_rx_ni(skb);
 }
 
 static int vcan_tx(struct sk_buff *skb, struct net_device *dev)

diff --git a/net/can/af_can.c b/net/can/af_can.c
index e733725b11d4cdbc1010e65bc441fa2723bdb132..264c96883db073225aaf96a8cec5d0518f253b25 100644 (file)
--- 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++;