can: fix NOHZ local_softirq_pending 08 warning

Oliver Hartkopp · davem330 · commit 481a8199142c · 2009-09-15T01:31:34.000-07:00
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 &lt;oliver@hartkopp.net&gt;
Signed-off-by: Urs Thuermann &lt;urs@isnogud.escape.de&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git 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 netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
diff --git 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++;

Original file line number	Diff line number	Diff line change
`@@ -80,7 +80,7 @@ static void vcan_rx(struct sk_buff skb, struct net_device dev)`
`80`	`80`	`skb->dev = dev;`
`81`	`81`	`skb->ip_summed = CHECKSUM_UNNECESSARY;`
`82`	`82`
`83`		`- netif_rx(skb);`
	`83`	`+ netif_rx_ni(skb);`
`84`	`84`	`}`
`85`	`85`
`86`	`86`	`static netdev_tx_t vcan_tx(struct sk_buff skb, struct net_device dev)`