can: c_can: Provide protection in the xmit path

The network core does not serialize the access to the hardware. The
xmit related code lets the following happen:

CPU0 	     	       CPU1
interrupt()
 do_poll()
   c_can_do_tx()
    Fiddle with HW and	xmit()
    internal data	  Fiddle with HW and
    	     		  internal data

due the complete lack of serialization.

Add proper locking.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 30a85aa81d456292a9e48cabd4d17763caccf9d7..1fe79ce50c5a35d2801dc9572ad9e0803a5d7d7a 100644 (file)
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -549,6 +549,7 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
        if (can_dropped_invalid_skb(dev, skb))
                return NETDEV_TX_OK;
 
+       spin_lock_bh(&priv->xmit_lock);
        msg_obj_no = get_tx_next_msg_obj(priv);
 
        /* prepare message object for transmission */
@@ -563,6 +564,7 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
        if (c_can_is_next_tx_obj_busy(priv, get_tx_next_msg_obj(priv)) ||
                        (priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) == 0)
                netif_stop_queue(dev);
+       spin_unlock_bh(&priv->xmit_lock);
 
        return NETDEV_TX_OK;
 }
@@ -787,7 +789,9 @@ static void c_can_do_tx(struct net_device *dev)
        struct c_can_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
 
-       for (/* nix */; (priv->tx_next - priv->tx_echo) > 0; priv->tx_echo++) {
+       spin_lock_bh(&priv->xmit_lock);
+
+       for (; (priv->tx_next - priv->tx_echo) > 0; priv->tx_echo++) {
                msg_obj_no = get_tx_echo_msg_obj(priv);
                val = c_can_read_reg32(priv, C_CAN_TXRQST1_REG);
                if (!(val & (1 << (msg_obj_no - 1)))) {
@@ -809,6 +813,8 @@ static void c_can_do_tx(struct net_device *dev)
        if (((priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) != 0) ||
                        ((priv->tx_echo & C_CAN_NEXT_MSG_OBJ_MASK) == 0))
                netif_wake_queue(dev);
+
+       spin_unlock_bh(&priv->xmit_lock);
 }
 
 /*
@@ -1262,6 +1268,7 @@ struct net_device *alloc_c_can_dev(void)
                return NULL;
 
        priv = netdev_priv(dev);
+       spin_lock_init(&priv->xmit_lock);
        netif_napi_add(dev, &priv->napi, c_can_poll, C_CAN_NAPI_WEIGHT);
 
        priv->dev = dev;

diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
index d2e1c21b143f4ae729edd45312de1db0a804f438..5097c802a61eb1f65fca1abe3ece9b4742f7daaf 100644 (file)
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
@@ -156,6 +156,7 @@ struct c_can_priv {
        struct napi_struct napi;
        struct net_device *dev;
        struct device *device;
+       spinlock_t xmit_lock;
        int tx_object;
        int current_status;
        int last_status;