can: provide library functions for skb allocation

This patch makes the private functions alloc_can_skb() and
alloc_can_err_skb() of the at91_can driver public and adapts all
drivers to use these. While making the patch I realized, that
the skb's are *not* setup consistently. It's now done as shown
below:

  skb->protocol = htons(ETH_P_CAN);
  skb->pkt_type = PACKET_BROADCAST;
  skb->ip_summed = CHECKSUM_UNNECESSARY;
  *cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
  memset(*cf, 0, sizeof(struct can_frame));

The frame is zeroed out to avoid uninitialized data to be passed to
user space. Some drivers or library code did not set "pkt_type" or
"ip_summed". Also,  "__constant_htons()" should not be used for
runtime invocations, as pointed out by David Miller.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 10 deletions

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 96d8be4253f8..1a9c5958bbd7 100644
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -296,11 +296,9 @@ static void sja1000_rx(struct net_device *dev)
         uint8_t dlc;
         int i;
 
-        skb = dev_alloc_skb(sizeof(struct can_frame));
+        skb = alloc_can_skb(dev, &cf);
         if (skb == NULL)
                 return;
-        skb->dev = dev;
-        skb->protocol = htons(ETH_P_CAN);
 
         fi = priv->read_reg(priv, REG_FI);
         dlc = fi & 0x0F;
@@ -351,15 +349,9 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
         enum can_state state = priv->can.state;
         uint8_t ecc, alc;
 
-        skb = dev_alloc_skb(sizeof(struct can_frame));
+        skb = alloc_can_err_skb(dev, &cf);
         if (skb == NULL)
                 return -ENOMEM;
-        skb->dev = dev;
-        skb->protocol = htons(ETH_P_CAN);
-        cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
-        memset(cf, 0, sizeof(struct can_frame));
-        cf->can_id = CAN_ERR_FLAG;
-        cf->can_dlc = CAN_ERR_DLC;
 
         if (isrc & IRQ_DOI) {
                 /* data overrun interrupt */