1 files changed, 112 insertions, 64 deletions

diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index 2928f7003041..57611fd91229 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -14,6 +14,8 @@
  * Copyright (C) 2015 Valeo S.A.
  */
 
+#include <linux/spinlock.h>
+#include <linux/kernel.h>
 #include <linux/completion.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
@@ -23,7 +25,6 @@
 #include <linux/can/dev.h>
 #include <linux/can/error.h>
 
-#define MAX_TX_URBS                     16
 #define MAX_RX_URBS                     4
 #define START_TIMEOUT                   1000 /* msecs */
 #define STOP_TIMEOUT                    1000 /* msecs */
@@ -441,6 +442,7 @@ struct kvaser_usb_error_summary {
         };
 };
 
+/* Context for an outstanding, not yet ACKed, transmission */
 struct kvaser_usb_tx_urb_context {
         struct kvaser_usb_net_priv *priv;
         u32 echo_index;
@@ -454,8 +456,13 @@ struct kvaser_usb {
         struct usb_endpoint_descriptor *bulk_in, *bulk_out;
         struct usb_anchor rx_submitted;
 
+        /* @max_tx_urbs: Firmware-reported maximum number of oustanding,
+         * not yet ACKed, transmissions on this device. This value is
+         * also used as a sentinel for marking free tx contexts.
+         */
         u32 fw_version;
         unsigned int nchannels;
+        unsigned int max_tx_urbs;
         enum kvaser_usb_family family;
 
         bool rxinitdone;
@@ -465,18 +472,18 @@ struct kvaser_usb {
 
 struct kvaser_usb_net_priv {
         struct can_priv can;
-
-        atomic_t active_tx_urbs;
-        struct usb_anchor tx_submitted;
-        struct kvaser_usb_tx_urb_context tx_contexts[MAX_TX_URBS];
-
-        struct completion start_comp, stop_comp;
+        struct can_berr_counter bec;
 
         struct kvaser_usb *dev;
         struct net_device *netdev;
         int channel;
 
-        struct can_berr_counter bec;
+        struct completion start_comp, stop_comp;
+        struct usb_anchor tx_submitted;
+
+        spinlock_t tx_contexts_lock;
+        int active_tx_contexts;
+        struct kvaser_usb_tx_urb_context tx_contexts[];
 };
 
 static const struct usb_device_id kvaser_usb_table[] = {
@@ -584,8 +591,15 @@ static int kvaser_usb_wait_msg(const struct kvaser_usb *dev, u8 id,
                 while (pos <= actual_len - MSG_HEADER_LEN) {
                         tmp = buf + pos;
 
-                        if (!tmp->len)
-                                break;
+                        /* Handle messages crossing the USB endpoint max packet
+                         * size boundary. Check kvaser_usb_read_bulk_callback()
+                         * for further details.
+                         */
+                        if (tmp->len == 0) {
+                                pos = round_up(pos, le16_to_cpu(dev->bulk_in->
+                                                                wMaxPacketSize));
+                                continue;
+                        }
 
                         if (pos + tmp->len > actual_len) {
                                 dev_err(dev->udev->dev.parent,
@@ -647,9 +661,13 @@ static int kvaser_usb_get_software_info(struct kvaser_usb *dev)
         switch (dev->family) {
         case KVASER_LEAF:
                 dev->fw_version = le32_to_cpu(msg.u.leaf.softinfo.fw_version);
+                dev->max_tx_urbs =
+                        le16_to_cpu(msg.u.leaf.softinfo.max_outstanding_tx);
                 break;
         case KVASER_USBCAN:
                 dev->fw_version = le32_to_cpu(msg.u.usbcan.softinfo.fw_version);
+                dev->max_tx_urbs =
+                        le16_to_cpu(msg.u.usbcan.softinfo.max_outstanding_tx);
                 break;
         }
 
@@ -686,6 +704,7 @@ static void kvaser_usb_tx_acknowledge(const struct kvaser_usb *dev,
         struct kvaser_usb_net_priv *priv;
         struct sk_buff *skb;
         struct can_frame *cf;
+        unsigned long flags;
         u8 channel, tid;
 
         channel = msg->u.tx_acknowledge_header.channel;
@@ -704,7 +723,7 @@ static void kvaser_usb_tx_acknowledge(const struct kvaser_usb *dev,
 
         stats = &priv->netdev->stats;
 
-        context = &priv->tx_contexts[tid % MAX_TX_URBS];
+        context = &priv->tx_contexts[tid % dev->max_tx_urbs];
 
         /* Sometimes the state change doesn't come after a bus-off event */
         if (priv->can.restart_ms &&
@@ -729,12 +748,15 @@ static void kvaser_usb_tx_acknowledge(const struct kvaser_usb *dev,
 
         stats->tx_packets++;
         stats->tx_bytes += context->dlc;
-        can_get_echo_skb(priv->netdev, context->echo_index);
 
-        context->echo_index = MAX_TX_URBS;
-        atomic_dec(&priv->active_tx_urbs);
+        spin_lock_irqsave(&priv->tx_contexts_lock, flags);
 
+        can_get_echo_skb(priv->netdev, context->echo_index);
+        context->echo_index = dev->max_tx_urbs;
+        --priv->active_tx_contexts;
         netif_wake_queue(priv->netdev);
+
+        spin_unlock_irqrestore(&priv->tx_contexts_lock, flags);
 }
 
 static void kvaser_usb_simple_msg_callback(struct urb *urb)
@@ -787,7 +809,6 @@ static int kvaser_usb_simple_msg_async(struct kvaser_usb_net_priv *priv,
                 netdev_err(netdev, "Error transmitting URB\n");
                 usb_unanchor_urb(urb);
                 usb_free_urb(urb);
-                kfree(buf);
                 return err;
         }
 
@@ -796,17 +817,6 @@ static int kvaser_usb_simple_msg_async(struct kvaser_usb_net_priv *priv,
         return 0;
 }
 
-static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
-{
-        int i;
-
-        usb_kill_anchored_urbs(&priv->tx_submitted);
-        atomic_set(&priv->active_tx_urbs, 0);
-
-        for (i = 0; i < MAX_TX_URBS; i++)
-                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 can_frame *cf)
@@ -1317,8 +1327,20 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb)
         while (pos <= urb->actual_length - MSG_HEADER_LEN) {
                 msg = urb->transfer_buffer + pos;
 
-                if (!msg->len)
-                        break;
+                /* The Kvaser firmware can only read and write messages that
+                 * does not cross the USB's endpoint wMaxPacketSize boundary.
+                 * If a follow-up command crosses such boundary, firmware puts
+                 * a placeholder zero-length command in its place then aligns
+                 * the real command to the next max packet size.
+                 *
+                 * Handle such cases or we're going to miss a significant
+                 * number of events in case of a heavy rx load on the bus.
+                 */
+                if (msg->len == 0) {
+                        pos = round_up(pos, le16_to_cpu(dev->bulk_in->
+                                                        wMaxPacketSize));
+                        continue;
+                }
 
                 if (pos + msg->len > urb->actual_length) {
                         dev_err(dev->udev->dev.parent, "Format error\n");
@@ -1326,7 +1348,6 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb)
                 }
 
                 kvaser_usb_handle_message(dev, msg);
-
                 pos += msg->len;
         }
 
@@ -1498,6 +1519,26 @@ error:
         return err;
 }
 
+static void kvaser_usb_reset_tx_urb_contexts(struct kvaser_usb_net_priv *priv)
+{
+        int i, max_tx_urbs;
+
+        max_tx_urbs = priv->dev->max_tx_urbs;
+
+        priv->active_tx_contexts = 0;
+        for (i = 0; i < max_tx_urbs; i++)
+                priv->tx_contexts[i].echo_index = max_tx_urbs;
+}
+
+/* This method might sleep. Do not call it in the atomic context
+ * of URB completions.
+ */
+static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
+{
+        usb_kill_anchored_urbs(&priv->tx_submitted);
+        kvaser_usb_reset_tx_urb_contexts(priv);
+}
+
 static void kvaser_usb_unlink_all_urbs(struct kvaser_usb *dev)
 {
         int i;
@@ -1615,9 +1656,9 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
         struct urb *urb;
         void *buf;
         struct kvaser_msg *msg;
-        int i, err;
-        int ret = NETDEV_TX_OK;
+        int i, err, ret = NETDEV_TX_OK;
         u8 *msg_tx_can_flags = NULL;            /* GCC */
+        unsigned long flags;
 
         if (can_dropped_invalid_skb(netdev, skb))
                 return NETDEV_TX_OK;
@@ -1634,7 +1675,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
         if (!buf) {
                 stats->tx_dropped++;
                 dev_kfree_skb(skb);
-                goto nobufmem;
+                goto freeurb;
         }
 
         msg = buf;
@@ -1671,22 +1712,32 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
         if (cf->can_id & CAN_RTR_FLAG)
                 *msg_tx_can_flags |= MSG_FLAG_REMOTE_FRAME;
 
-        for (i = 0; i < ARRAY_SIZE(priv->tx_contexts); i++) {
-                if (priv->tx_contexts[i].echo_index == MAX_TX_URBS) {
+        spin_lock_irqsave(&priv->tx_contexts_lock, flags);
+        for (i = 0; i < dev->max_tx_urbs; i++) {
+                if (priv->tx_contexts[i].echo_index == dev->max_tx_urbs) {
                         context = &priv->tx_contexts[i];
+
+                        context->echo_index = i;
+                        can_put_echo_skb(skb, netdev, context->echo_index);
+                        ++priv->active_tx_contexts;
+                        if (priv->active_tx_contexts >= dev->max_tx_urbs)
+                                netif_stop_queue(netdev);
+
                         break;
                 }
         }
+        spin_unlock_irqrestore(&priv->tx_contexts_lock, flags);
 
         /* This should never happen; it implies a flow control bug */
         if (!context) {
                 netdev_warn(netdev, "cannot find free context\n");
+
+                kfree(buf);
                 ret =  NETDEV_TX_BUSY;
-                goto releasebuf;
+                goto freeurb;
         }
 
         context->priv = priv;
-        context->echo_index = i;
         context->dlc = cf->can_dlc;
 
         msg->u.tx_can.tid = context->echo_index;
@@ -1698,18 +1749,17 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
                           kvaser_usb_write_bulk_callback, context);
         usb_anchor_urb(urb, &priv->tx_submitted);
 
-        can_put_echo_skb(skb, netdev, context->echo_index);
-
-        atomic_inc(&priv->active_tx_urbs);
-
-        if (atomic_read(&priv->active_tx_urbs) >= MAX_TX_URBS)
-                netif_stop_queue(netdev);
-
         err = usb_submit_urb(urb, GFP_ATOMIC);
         if (unlikely(err)) {
+                spin_lock_irqsave(&priv->tx_contexts_lock, flags);
+
                 can_free_echo_skb(netdev, context->echo_index);
+                context->echo_index = dev->max_tx_urbs;
+                --priv->active_tx_contexts;
+                netif_wake_queue(netdev);
+
+                spin_unlock_irqrestore(&priv->tx_contexts_lock, flags);
 
-                atomic_dec(&priv->active_tx_urbs);
                 usb_unanchor_urb(urb);
 
                 stats->tx_dropped++;
@@ -1719,16 +1769,12 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
                 else
                         netdev_warn(netdev, "Failed tx_urb %d\n", err);
 
-                goto releasebuf;
+                goto freeurb;
         }
 
-        usb_free_urb(urb);
-
-        return NETDEV_TX_OK;
+        ret = NETDEV_TX_OK;
 
-releasebuf:
-        kfree(buf);
-nobufmem:
+freeurb:
         usb_free_urb(urb);
         return ret;
 }
@@ -1840,13 +1886,15 @@ static int kvaser_usb_init_one(struct usb_interface *intf,
         struct kvaser_usb *dev = usb_get_intfdata(intf);
         struct net_device *netdev;
         struct kvaser_usb_net_priv *priv;
-        int i, err;
+        int err;
 
         err = kvaser_usb_send_simple_msg(dev, CMD_RESET_CHIP, channel);
         if (err)
                 return err;
 
-        netdev = alloc_candev(sizeof(*priv), MAX_TX_URBS);
+        netdev = alloc_candev(sizeof(*priv) +
+                              dev->max_tx_urbs * sizeof(*priv->tx_contexts),
+                              dev->max_tx_urbs);
         if (!netdev) {
                 dev_err(&intf->dev, "Cannot alloc candev\n");
                 return -ENOMEM;
@@ -1854,19 +1902,17 @@ static int kvaser_usb_init_one(struct usb_interface *intf,
 
         priv = netdev_priv(netdev);
 
+        init_usb_anchor(&priv->tx_submitted);
         init_completion(&priv->start_comp);
         init_completion(&priv->stop_comp);
 
-        init_usb_anchor(&priv->tx_submitted);
-        atomic_set(&priv->active_tx_urbs, 0);
-
-        for (i = 0; i < ARRAY_SIZE(priv->tx_contexts); i++)
-                priv->tx_contexts[i].echo_index = MAX_TX_URBS;
-
         priv->dev = dev;
         priv->netdev = netdev;
         priv->channel = channel;
 
+        spin_lock_init(&priv->tx_contexts_lock);
+        kvaser_usb_reset_tx_urb_contexts(priv);
+
         priv->can.state = CAN_STATE_STOPPED;
         priv->can.clock.freq = CAN_USB_CLOCK;
         priv->can.bittiming_const = &kvaser_usb_bittiming_const;
@@ -1976,6 +2022,13 @@ static int kvaser_usb_probe(struct usb_interface *intf,
                 return err;
         }
 
+        dev_dbg(&intf->dev, "Firmware version: %d.%d.%d\n",
+                ((dev->fw_version >> 24) & 0xff),
+                ((dev->fw_version >> 16) & 0xff),
+                (dev->fw_version & 0xffff));
+
+        dev_dbg(&intf->dev, "Max oustanding tx = %d URBs\n", dev->max_tx_urbs);
+
         err = kvaser_usb_get_card_info(dev);
         if (err) {
                 dev_err(&intf->dev,
@@ -1983,11 +2036,6 @@ static int kvaser_usb_probe(struct usb_interface *intf,
                 return err;
         }
 
-        dev_dbg(&intf->dev, "Firmware version: %d.%d.%d\n",
-                ((dev->fw_version >> 24) & 0xff),
-                ((dev->fw_version >> 16) & 0xff),
-                (dev->fw_version & 0xffff));
-
         for (i = 0; i < dev->nchannels; i++) {
                 err = kvaser_usb_init_one(intf, id, i);
                 if (err) {