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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
* Copyright (C) 2006 Andrey Volkov, Varma Electronics
* Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
*/
#include <linux/can/dev.h>
/* Local echo of CAN messages
*
* CAN network devices *should* support a local echo functionality
* (see Documentation/networking/can.rst). To test the handling of CAN
* interfaces that do not support the local echo both driver types are
* implemented. In the case that the driver does not support the echo
* the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
* to perform the echo as a fallback solution.
*/
void can_flush_echo_skb(struct net_device *dev)
{
struct can_priv *priv = netdev_priv(dev);
struct net_device_stats *stats = &dev->stats;
int i;
for (i = 0; i < priv->echo_skb_max; i++) {
if (priv->echo_skb[i]) {
kfree_skb(priv->echo_skb[i]);
priv->echo_skb[i] = NULL;
stats->tx_dropped++;
stats->tx_aborted_errors++;
}
}
}
/* Put the skb on the stack to be looped backed locally lateron
*
* The function is typically called in the start_xmit function
* of the device driver. The driver must protect access to
* priv->echo_skb, if necessary.
*/
int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
unsigned int idx, unsigned int frame_len)
{
struct can_priv *priv = netdev_priv(dev);
BUG_ON(idx >= priv->echo_skb_max);
/* check flag whether this packet has to be looped back */
if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK ||
(skb->protocol != htons(ETH_P_CAN) &&
skb->protocol != htons(ETH_P_CANFD))) {
kfree_skb(skb);
return 0;
}
if (!priv->echo_skb[idx]) {
skb = can_create_echo_skb(skb);
if (!skb)
return -ENOMEM;
/* make settings for echo to reduce code in irq context */
skb->pkt_type = PACKET_BROADCAST;
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb->dev = dev;
/* save frame_len to reuse it when transmission is completed */
can_skb_prv(skb)->frame_len = frame_len;
/* save this skb for tx interrupt echo handling */
priv->echo_skb[idx] = skb;
} else {
/* locking problem with netif_stop_queue() ?? */
netdev_err(dev, "%s: BUG! echo_skb %d is occupied!\n", __func__, idx);
kfree_skb(skb);
return -EBUSY;
}
return 0;
}
EXPORT_SYMBOL_GPL(can_put_echo_skb);
struct sk_buff *
__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr,
unsigned int *frame_len_ptr)
{
struct can_priv *priv = netdev_priv(dev);
if (idx >= priv->echo_skb_max) {
netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
__func__, idx, priv->echo_skb_max);
return NULL;
}
if (priv->echo_skb[idx]) {
/* Using "struct canfd_frame::len" for the frame
* length is supported on both CAN and CANFD frames.
*/
struct sk_buff *skb = priv->echo_skb[idx];
struct can_skb_priv *can_skb_priv = can_skb_prv(skb);
struct canfd_frame *cf = (struct canfd_frame *)skb->data;
/* get the real payload length for netdev statistics */
if (cf->can_id & CAN_RTR_FLAG)
*len_ptr = 0;
else
*len_ptr = cf->len;
if (frame_len_ptr)
*frame_len_ptr = can_skb_priv->frame_len;
priv->echo_skb[idx] = NULL;
return skb;
}
return NULL;
}
/* Get the skb from the stack and loop it back locally
*
* The function is typically called when the TX done interrupt
* is handled in the device driver. The driver must protect
* access to priv->echo_skb, if necessary.
*/
unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx)
{
struct sk_buff *skb;
u8 len;
skb = __can_get_echo_skb(dev, idx, &len, NULL);
if (!skb)
return 0;
skb_get(skb);
if (netif_rx(skb) == NET_RX_SUCCESS)
dev_consume_skb_any(skb);
else
dev_kfree_skb_any(skb);
return len;
}
EXPORT_SYMBOL_GPL(can_get_echo_skb);
/* Remove the skb from the stack and free it.
*
* The function is typically called when TX failed.
*/
void can_free_echo_skb(struct net_device *dev, unsigned int idx)
{
struct can_priv *priv = netdev_priv(dev);
BUG_ON(idx >= priv->echo_skb_max);
if (priv->echo_skb[idx]) {
dev_kfree_skb_any(priv->echo_skb[idx]);
priv->echo_skb[idx] = NULL;
}
}
EXPORT_SYMBOL_GPL(can_free_echo_skb);
struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
{
struct sk_buff *skb;
skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
sizeof(struct can_frame));
if (unlikely(!skb))
return NULL;
skb->protocol = htons(ETH_P_CAN);
skb->pkt_type = PACKET_BROADCAST;
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb_reset_mac_header(skb);
skb_reset_network_header(skb);
skb_reset_transport_header(skb);
can_skb_reserve(skb);
can_skb_prv(skb)->ifindex = dev->ifindex;
can_skb_prv(skb)->skbcnt = 0;
*cf = skb_put_zero(skb, sizeof(struct can_frame));
return skb;
}
EXPORT_SYMBOL_GPL(alloc_can_skb);
struct sk_buff *alloc_canfd_skb(struct net_device *dev,
struct canfd_frame **cfd)
{
struct sk_buff *skb;
skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
sizeof(struct canfd_frame));
if (unlikely(!skb))
return NULL;
skb->protocol = htons(ETH_P_CANFD);
skb->pkt_type = PACKET_BROADCAST;
skb->ip_summed = CHECKSUM_UNNECESSARY;
skb_reset_mac_header(skb);
skb_reset_network_header(skb);
skb_reset_transport_header(skb);
can_skb_reserve(skb);
can_skb_prv(skb)->ifindex = dev->ifindex;
can_skb_prv(skb)->skbcnt = 0;
*cfd = skb_put_zero(skb, sizeof(struct canfd_frame));
return skb;
}
EXPORT_SYMBOL_GPL(alloc_canfd_skb);
struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
{
struct sk_buff *skb;
skb = alloc_can_skb(dev, cf);
if (unlikely(!skb))
return NULL;
(*cf)->can_id = CAN_ERR_FLAG;
(*cf)->len = CAN_ERR_DLC;
return skb;
}
EXPORT_SYMBOL_GPL(alloc_can_err_skb);
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