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>
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@ -122,7 +122,6 @@
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/* IFx message control */
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#define IF_MCONT_NEWDAT BIT(15)
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#define IF_MCONT_MSGLST BIT(14)
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#define IF_MCONT_CLR_MSGLST (0 << 14)
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#define IF_MCONT_INTPND BIT(13)
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#define IF_MCONT_UMASK BIT(12)
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#define IF_MCONT_TXIE BIT(11)
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@ -411,27 +410,22 @@ static inline void c_can_activate_rx_msg_obj(struct net_device *dev,
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c_can_object_put(dev, iface, obj, IF_COMM_CONTROL);
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}
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static void c_can_handle_lost_msg_obj(struct net_device *dev,
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int iface, int objno)
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static int c_can_handle_lost_msg_obj(struct net_device *dev,
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int iface, int objno, u32 ctrl)
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{
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struct c_can_priv *priv = netdev_priv(dev);
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struct net_device_stats *stats = &dev->stats;
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struct sk_buff *skb;
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struct c_can_priv *priv = netdev_priv(dev);
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struct can_frame *frame;
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struct sk_buff *skb;
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netdev_err(dev, "msg lost in buffer %d\n", objno);
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c_can_object_get(dev, iface, objno, IF_COMM_ALL & ~IF_COMM_TXRQST);
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priv->write_reg(priv, C_CAN_IFACE(MSGCTRL_REG, iface),
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IF_MCONT_CLR_MSGLST);
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ctrl &= ~(IF_MCONT_MSGLST | IF_MCONT_INTPND | IF_MCONT_NEWDAT);
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priv->write_reg(priv, C_CAN_IFACE(MSGCTRL_REG, iface), ctrl);
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c_can_object_put(dev, iface, objno, IF_COMM_CONTROL);
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/* create an error msg */
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skb = alloc_can_err_skb(dev, &frame);
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if (unlikely(!skb))
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return;
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return 0;
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frame->can_id |= CAN_ERR_CRTL;
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frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
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@ -439,6 +433,7 @@ static void c_can_handle_lost_msg_obj(struct net_device *dev,
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stats->rx_over_errors++;
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netif_receive_skb(skb);
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return 1;
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}
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static int c_can_read_msg_object(struct net_device *dev, int iface, int ctrl)
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@ -910,9 +905,13 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
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C_CAN_IFACE(MSGCTRL_REG, IF_RX));
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if (msg_ctrl_save & IF_MCONT_MSGLST) {
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c_can_handle_lost_msg_obj(dev, IF_RX, msg_obj);
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num_rx_pkts++;
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quota--;
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int n;
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n = c_can_handle_lost_msg_obj(dev, IF_RX,
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msg_obj,
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msg_ctrl_save);
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num_rx_pkts += n;
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quota -=n;
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continue;
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}
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