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Commit bf88a206 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Marc Kleine-Budde
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 710c5610

drivers/net/can/c_can/c_can.c

+8 −1
Original line number Diff line number Diff line
@@ -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;

drivers/net/can/c_can/c_can.h

+1 −0
Original line number Diff line number Diff line
@@ -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;