can: xilinx_can: Fix usage of skb memory

As per linux can framework, driver not allowed to touch the skb memory
after can_put_echo_skb() call.
This patch fixes the same.
https://www.spinics.net/lists/linux-can/msg02199.html

Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
Reviewed-by: Appana Durga Kedareswara Rao <appana.durga.rao@xilinx.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index c5f05b994435df7b1d8cb4a76ef24c3792bfc3ff..464af939cd8af53f8f00ac84268749d1ae056113 100644 (file)
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -542,16 +542,17 @@ static int xcan_do_set_mode(struct net_device *ndev, enum can_mode mode)
 
 /**
  * xcan_write_frame - Write a frame to HW
- * @priv:              Driver private data structure
+ * @ndev:              Pointer to net_device structure
  * @skb:               sk_buff pointer that contains data to be Txed
  * @frame_offset:      Register offset to write the frame to
  */
-static void xcan_write_frame(struct xcan_priv *priv, struct sk_buff *skb,
+static void xcan_write_frame(struct net_device *ndev, struct sk_buff *skb,
                             int frame_offset)
 {
        u32 id, dlc, data[2] = {0, 0};
        struct canfd_frame *cf = (struct canfd_frame *)skb->data;
        u32 ramoff, dwindex = 0, i;
+       struct xcan_priv *priv = netdev_priv(ndev);
 
        /* Watch carefully on the bit sequence */
        if (cf->can_id & CAN_EFF_FLAG) {
@@ -587,6 +588,14 @@ static void xcan_write_frame(struct xcan_priv *priv, struct sk_buff *skb,
                dlc |= XCAN_DLCR_EDL_MASK;
        }
 
+       if (!(priv->devtype.flags & XCAN_FLAG_TX_MAILBOXES) &&
+           (priv->devtype.flags & XCAN_FLAG_TXFEMP))
+               can_put_echo_skb(skb, ndev, priv->tx_head % priv->tx_max);
+       else
+               can_put_echo_skb(skb, ndev, 0);
+
+       priv->tx_head++;
+
        priv->write_reg(priv, XCAN_FRAME_ID_OFFSET(frame_offset), id);
        /* If the CAN frame is RTR frame this write triggers transmission
         * (not on CAN FD)
@@ -638,13 +647,9 @@ static int xcan_start_xmit_fifo(struct sk_buff *skb, struct net_device *ndev)
                        XCAN_SR_TXFLL_MASK))
                return -ENOSPC;
 
-       can_put_echo_skb(skb, ndev, priv->tx_head % priv->tx_max);
-
        spin_lock_irqsave(&priv->tx_lock, flags);
 
-       priv->tx_head++;
-
-       xcan_write_frame(priv, skb, XCAN_TXFIFO_OFFSET);
+       xcan_write_frame(ndev, skb, XCAN_TXFIFO_OFFSET);
 
        /* Clear TX-FIFO-empty interrupt for xcan_tx_interrupt() */
        if (priv->tx_max > 1)
@@ -675,13 +680,9 @@ static int xcan_start_xmit_mailbox(struct sk_buff *skb, struct net_device *ndev)
                     BIT(XCAN_TX_MAILBOX_IDX)))
                return -ENOSPC;
 
-       can_put_echo_skb(skb, ndev, 0);
-
        spin_lock_irqsave(&priv->tx_lock, flags);
 
-       priv->tx_head++;
-
-       xcan_write_frame(priv, skb,
+       xcan_write_frame(ndev, skb,
                         XCAN_TXMSG_FRAME_OFFSET(XCAN_TX_MAILBOX_IDX));
 
        /* Mark buffer as ready for transmit */