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authorThomas Gleixner <tglx@linutronix.de>2014-03-18 17:19:10 +0000
committerMarc Kleine-Budde <mkl@pengutronix.de>2014-04-01 11:54:59 +0200
commit07c7b6f6161be52b8ab6bca70ed6a7140708c94e (patch)
tree66410feb92de31d004ec2dfbf3cf69d307145cb0
parent64f08f2f3544eb8b6b14fd35e6087d7d3ede77cd (diff)
downloadop-kernel-dev-07c7b6f6161be52b8ab6bca70ed6a7140708c94e.zip
op-kernel-dev-07c7b6f6161be52b8ab6bca70ed6a7140708c94e.tar.gz
can: c_can: Fix the lost message handling
The lost message handling is broken in several ways. 1) Clearing the message lost flag is done by writing 0 to the message control register of the object. #define IF_MCONT_CLR_MSGLST (0 << 14) That clears the object buffer configuration in the worst case, which results in a loss of the EOB flag. That leaves the FIFO chain without a limit and causes a complete lockup of the HW 2) In case that the error skb allocation fails, the code happily claims that it handed down a packet. Just an accounting bug, but .... 3) The code adds a lot of pointless overhead to that error case, where we need to get stuff done as fast as possible to avoid more packet loss. - printk an annoying error message - reread the object buffer for nothing Fix is simple again: - Use the already known MSGCTRL content and only clear the MSGLST bit - Fix the buffer accounting by adding a proper return code - Remove the pointless operations Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
-rw-r--r--drivers/net/can/c_can/c_can.c31
1 files changed, 15 insertions, 16 deletions
diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index cef9967..ef5f3b8 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -122,7 +122,6 @@
/* IFx message control */
#define IF_MCONT_NEWDAT BIT(15)
#define IF_MCONT_MSGLST BIT(14)
-#define IF_MCONT_CLR_MSGLST (0 << 14)
#define IF_MCONT_INTPND BIT(13)
#define IF_MCONT_UMASK BIT(12)
#define IF_MCONT_TXIE BIT(11)
@@ -411,27 +410,22 @@ static inline void c_can_activate_rx_msg_obj(struct net_device *dev,
c_can_object_put(dev, iface, obj, IF_COMM_CONTROL);
}
-static void c_can_handle_lost_msg_obj(struct net_device *dev,
- int iface, int objno)
+static int c_can_handle_lost_msg_obj(struct net_device *dev,
+ int iface, int objno, u32 ctrl)
{
- struct c_can_priv *priv = netdev_priv(dev);
struct net_device_stats *stats = &dev->stats;
- struct sk_buff *skb;
+ struct c_can_priv *priv = netdev_priv(dev);
struct can_frame *frame;
+ struct sk_buff *skb;
- netdev_err(dev, "msg lost in buffer %d\n", objno);
-
- c_can_object_get(dev, iface, objno, IF_COMM_ALL & ~IF_COMM_TXRQST);
-
- priv->write_reg(priv, C_CAN_IFACE(MSGCTRL_REG, iface),
- IF_MCONT_CLR_MSGLST);
-
+ ctrl &= ~(IF_MCONT_MSGLST | IF_MCONT_INTPND | IF_MCONT_NEWDAT);
+ priv->write_reg(priv, C_CAN_IFACE(MSGCTRL_REG, iface), ctrl);
c_can_object_put(dev, iface, objno, IF_COMM_CONTROL);
/* create an error msg */
skb = alloc_can_err_skb(dev, &frame);
if (unlikely(!skb))
- return;
+ return 0;
frame->can_id |= CAN_ERR_CRTL;
frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
@@ -439,6 +433,7 @@ static void c_can_handle_lost_msg_obj(struct net_device *dev,
stats->rx_over_errors++;
netif_receive_skb(skb);
+ return 1;
}
static int c_can_read_msg_object(struct net_device *dev, int iface, int ctrl)
@@ -910,9 +905,13 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
C_CAN_IFACE(MSGCTRL_REG, IF_RX));
if (msg_ctrl_save & IF_MCONT_MSGLST) {
- c_can_handle_lost_msg_obj(dev, IF_RX, msg_obj);
- num_rx_pkts++;
- quota--;
+ int n;
+
+ n = c_can_handle_lost_msg_obj(dev, IF_RX,
+ msg_obj,
+ msg_ctrl_save);
+ num_rx_pkts += n;
+ quota -=n;
continue;
}
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