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 <t...@linutronix.de>
---
drivers/net/can/c_can/c_can.c | 9 ++++++++-
drivers/net/can/c_can/c_can.h | 1 +
2 files changed, 9 insertions(+), 1 deletion(-)
Index: linux/drivers/net/can/c_can/c_can.c
===================================================================
--- linux.orig/drivers/net/can/c_can/c_can.c
+++ linux/drivers/net/can/c_can/c_can.c
@@ -549,6 +549,7 @@ static netdev_tx_t c_can_start_xmit(stru
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(stru
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;
}
@@ -778,7 +780,9 @@ static void c_can_do_tx(struct net_devic
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)))) {
@@ -800,6 +804,8 @@ static void c_can_do_tx(struct net_devic
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);
}
/*
@@ -1250,6 +1256,7 @@ 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;
Index: linux/drivers/net/can/c_can/c_can.h
===================================================================
--- linux.orig/drivers/net/can/c_can/c_can.h
+++ linux/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;
--
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