Subject: [PATCH v6 5/7] can: kvaser_usb: Update interface state before exiting on OOM

From: "Ahmed S. Darwish" <[email-masked]>
Date: Mon, 26 Jan 2015 07:27:19 +0200

From: Ahmed S. Darwish <[email-masked]>

Update all of the can interface's state and error counters before
trying any skb allocation that can actually fail with -ENOMEM.

Suggested-by: Marc Kleine-Budde <[email-masked]>
Signed-off-by: Ahmed S. Darwish <[email-masked]>
---
 drivers/net/can/usb/kvaser_usb.c |  181 ++++++++++++++++++++++----------------
 1 files changed, 105 insertions(+), 76 deletions(-)

diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index 7af379c..f57ce55 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -273,6 +273,10 @@ struct kvaser_msg {
 	} u;
 } __packed;
 
+struct kvaser_usb_error_summary {
+	u8 channel, status, txerr, rxerr, error_factor;
+};
+
 struct kvaser_usb_tx_urb_context {
 	struct kvaser_usb_net_priv *priv;
 	u32 echo_index;
@@ -615,6 +619,54 @@ static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
 		priv->tx_contexts[i].echo_index = MAX_TX_URBS;
 }
 
+static void kvaser_usb_rx_error_update_can_state(struct kvaser_usb_net_priv *priv,
+						 const struct kvaser_usb_error_summary *es)
+{
+	struct net_device_stats *stats;
+	enum can_state new_state;
+
+	stats = &priv->netdev->stats;
+	new_state = priv->can.state;
+
+	netdev_dbg(priv->netdev, "Error status: 0x%02x\n", es->status);
+
+	if (es->status & (M16C_STATE_BUS_OFF | M16C_STATE_BUS_RESET)) {
+		priv->can.can_stats.bus_off++;
+		new_state = CAN_STATE_BUS_OFF;
+	} else if (es->status & M16C_STATE_BUS_PASSIVE) {
+		if (priv->can.state != CAN_STATE_ERROR_PASSIVE)
+			priv->can.can_stats.error_passive++;
+		new_state = CAN_STATE_ERROR_PASSIVE;
+	} else if (es->status & M16C_STATE_BUS_ERROR) {
+		if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
+		    ((es->txerr >= 96) || (es->rxerr >= 96))) {
+			priv->can.can_stats.error_warning++;
+			new_state = CAN_STATE_ERROR_WARNING;
+		} else if ((priv->can.state > CAN_STATE_ERROR_ACTIVE) &&
+			   ((es->txerr < 96) && (es->rxerr < 96))) {
+			new_state = CAN_STATE_ERROR_ACTIVE;
+		}
+	}
+
+	if (!es->status)
+		new_state = CAN_STATE_ERROR_ACTIVE;
+
+	if (priv->can.restart_ms &&
+	    (priv->can.state >= CAN_STATE_BUS_OFF) &&
+	    (new_state < CAN_STATE_BUS_OFF)) {
+		priv->can.can_stats.restarts++;
+	}
+
+	if (es->error_factor) {
+		priv->can.can_stats.bus_error++;
+		stats->rx_errors++;
+	}
+
+	priv->bec.txerr = es->txerr;
+	priv->bec.rxerr = es->rxerr;
+	priv->can.state = new_state;
+}
+
 static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
 				const struct kvaser_msg *msg)
 {
@@ -622,30 +674,30 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
 	struct sk_buff *skb;
 	struct net_device_stats *stats;
 	struct kvaser_usb_net_priv *priv;
-	unsigned int new_state;
-	u8 channel, status, txerr, rxerr, error_factor;
+	struct kvaser_usb_error_summary es = { };
+	enum can_state old_state;
 
 	switch (msg->id) {
 	case CMD_CAN_ERROR_EVENT:
-		channel = msg->u.error_event.channel;
-		status =  msg->u.error_event.status;
-		txerr = msg->u.error_event.tx_errors_count;
-		rxerr = msg->u.error_event.rx_errors_count;
-		error_factor = msg->u.error_event.error_factor;
+		es.channel = msg->u.error_event.channel;
+		es.status =  msg->u.error_event.status;
+		es.txerr = msg->u.error_event.tx_errors_count;
+		es.rxerr = msg->u.error_event.rx_errors_count;
+		es.error_factor = msg->u.error_event.error_factor;
 		break;
 	case CMD_LOG_MESSAGE:
-		channel = msg->u.log_message.channel;
-		status = msg->u.log_message.data[0];
-		txerr = msg->u.log_message.data[2];
-		rxerr = msg->u.log_message.data[3];
-		error_factor = msg->u.log_message.data[1];
+		es.channel = msg->u.log_message.channel;
+		es.status = msg->u.log_message.data[0];
+		es.txerr = msg->u.log_message.data[2];
+		es.rxerr = msg->u.log_message.data[3];
+		es.error_factor = msg->u.log_message.data[1];
 		break;
 	case CMD_CHIP_STATE_EVENT:
-		channel = msg->u.chip_state_event.channel;
-		status =  msg->u.chip_state_event.status;
-		txerr = msg->u.chip_state_event.tx_errors_count;
-		rxerr = msg->u.chip_state_event.rx_errors_count;
-		error_factor = 0;
+		es.channel = msg->u.chip_state_event.channel;
+		es.status =  msg->u.chip_state_event.status;
+		es.txerr = msg->u.chip_state_event.tx_errors_count;
+		es.rxerr = msg->u.chip_state_event.rx_errors_count;
+		es.error_factor = 0;
 		break;
 	default:
 		dev_err(dev->udev->dev.parent, "Invalid msg id (%d)\n",
@@ -653,116 +705,93 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
 		return;
 	}
 
-	if (channel >= dev->nchannels) {
+	if (es.channel >= dev->nchannels) {
 		dev_err(dev->udev->dev.parent,
-			"Invalid channel number (%d)\n", channel);
+			"Invalid channel number (%d)\n", es.channel);
 		return;
 	}
 
-	priv = dev->nets[channel];
+	priv = dev->nets[es.channel];
 	stats = &priv->netdev->stats;
 
+	/* Update all of the can interface's state and error counters before
+	 * trying any skb allocation that can actually fail with -ENOMEM.
+	 */
+	old_state = priv->can.state;
+	kvaser_usb_rx_error_update_can_state(priv, &es);
+
 	skb = alloc_can_err_skb(priv->netdev, &cf);
 	if (!skb) {
 		stats->rx_dropped++;
 		return;
 	}
 
-	new_state = priv->can.state;
-
-	netdev_dbg(priv->netdev, "Error status: 0x%02x\n", status);
-
-	if (status & (M16C_STATE_BUS_OFF | M16C_STATE_BUS_RESET)) {
+	if (es.status & (M16C_STATE_BUS_OFF | M16C_STATE_BUS_RESET)) {
 		cf->can_id |= CAN_ERR_BUSOFF;
 
-		priv->can.can_stats.bus_off++;
 		if (!priv->can.restart_ms)
 			kvaser_usb_simple_msg_async(priv, CMD_STOP_CHIP);
-
 		netif_carrier_off(priv->netdev);
-
-		new_state = CAN_STATE_BUS_OFF;
-	} else if (status & M16C_STATE_BUS_PASSIVE) {
-		if (priv->can.state != CAN_STATE_ERROR_PASSIVE) {
+	} else if (es.status & M16C_STATE_BUS_PASSIVE) {
+		if (old_state != CAN_STATE_ERROR_PASSIVE) {
 			cf->can_id |= CAN_ERR_CRTL;
 
-			if (txerr || rxerr)
-				cf->data[1] = (txerr > rxerr)
+			if (es.txerr || es.rxerr)
+				cf->data[1] = (es.txerr > es.rxerr)
 						? CAN_ERR_CRTL_TX_PASSIVE
 						: CAN_ERR_CRTL_RX_PASSIVE;
 			else
 				cf->data[1] = CAN_ERR_CRTL_TX_PASSIVE |
 					      CAN_ERR_CRTL_RX_PASSIVE;
-
-			priv->can.can_stats.error_passive++;
 		}
-
-		new_state = CAN_STATE_ERROR_PASSIVE;
-	} else if (status & M16C_STATE_BUS_ERROR) {
-		if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
-		    ((txerr >= 96) || (rxerr >= 96))) {
+	} else if (es.status & M16C_STATE_BUS_ERROR) {
+		if ((old_state < CAN_STATE_ERROR_WARNING) &&
+		    ((es.txerr >= 96) || (es.rxerr >= 96))) {
 			cf->can_id |= CAN_ERR_CRTL;
-			cf->data[1] = (txerr > rxerr)
+			cf->data[1] = (es.txerr > es.rxerr)
 					? CAN_ERR_CRTL_TX_WARNING
 					: CAN_ERR_CRTL_RX_WARNING;
-
-			priv->can.can_stats.error_warning++;
-			new_state = CAN_STATE_ERROR_WARNING;
-		} else if ((priv->can.state > CAN_STATE_ERROR_ACTIVE) &&
-			   ((txerr < 96) && (rxerr < 96))) {
+		} else if ((old_state > CAN_STATE_ERROR_ACTIVE) &&
+			   ((es.txerr < 96) && (es.rxerr < 96))) {
 			cf->can_id |= CAN_ERR_PROT;
 			cf->data[2] = CAN_ERR_PROT_ACTIVE;
-
-			new_state = CAN_STATE_ERROR_ACTIVE;
 		}
 	}
 
-	if (!status) {
+	if (!es.status) {
 		cf->can_id |= CAN_ERR_PROT;
 		cf->data[2] = CAN_ERR_PROT_ACTIVE;
-
-		new_state = CAN_STATE_ERROR_ACTIVE;
 	}
 
 	if (priv->can.restart_ms &&
-	    (priv->can.state >= CAN_STATE_BUS_OFF) &&
-	    (new_state < CAN_STATE_BUS_OFF)) {
+	    (old_state >= CAN_STATE_BUS_OFF) &&
+	    (priv->can.state < CAN_STATE_BUS_OFF)) {
 		cf->can_id |= CAN_ERR_RESTARTED;
 		netif_carrier_on(priv->netdev);
-
-		priv->can.can_stats.restarts++;
 	}
 
-	if (error_factor) {
-		priv->can.can_stats.bus_error++;
-		stats->rx_errors++;
-
+	if (es.error_factor) {
 		cf->can_id |= CAN_ERR_BUSERROR | CAN_ERR_PROT;
 
-		if (error_factor & M16C_EF_ACKE)
+		if (es.error_factor & M16C_EF_ACKE)
 			cf->data[3] |= (CAN_ERR_PROT_LOC_ACK);
-		if (error_factor & M16C_EF_CRCE)
+		if (es.error_factor & M16C_EF_CRCE)
 			cf->data[3] |= (CAN_ERR_PROT_LOC_CRC_SEQ |
 					CAN_ERR_PROT_LOC_CRC_DEL);
-		if (error_factor & M16C_EF_FORME)
+		if (es.error_factor & M16C_EF_FORME)
 			cf->data[2] |= CAN_ERR_PROT_FORM;
-		if (error_factor & M16C_EF_STFE)
+		if (es.error_factor & M16C_EF_STFE)
 			cf->data[2] |= CAN_ERR_PROT_STUFF;
-		if (error_factor & M16C_EF_BITE0)
+		if (es.error_factor & M16C_EF_BITE0)
 			cf->data[2] |= CAN_ERR_PROT_BIT0;
-		if (error_factor & M16C_EF_BITE1)
+		if (es.error_factor & M16C_EF_BITE1)
 			cf->data[2] |= CAN_ERR_PROT_BIT1;
-		if (error_factor & M16C_EF_TRE)
+		if (es.error_factor & M16C_EF_TRE)
 			cf->data[2] |= CAN_ERR_PROT_TX;
 	}
 
-	cf->data[6] = txerr;
-	cf->data[7] = rxerr;
-
-	priv->bec.txerr = txerr;
-	priv->bec.rxerr = rxerr;
-
-	priv->can.state = new_state;
+	cf->data[6] = es.txerr;
+	cf->data[7] = es.rxerr;
 
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
@@ -786,6 +815,9 @@ static void kvaser_usb_rx_can_err(const struct kvaser_usb_net_priv *priv,
 	}
 
 	if (msg->u.rx_can.flag & MSG_FLAG_OVERRUN) {
+		stats->rx_over_errors++;
+		stats->rx_errors++;
+
 		skb = alloc_can_err_skb(priv->netdev, &cf);
 		if (!skb) {
 			stats->rx_dropped++;
@@ -795,9 +827,6 @@ static void kvaser_usb_rx_can_err(const struct kvaser_usb_net_priv *priv,
 		cf->can_id |= CAN_ERR_CRTL;
 		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
 
-		stats->rx_over_errors++;
-		stats->rx_errors++;
-
 		stats->rx_packets++;
 		stats->rx_bytes += cf->can_dlc;
 		netif_rx(skb);
-- 
1.7.7.6