can: make use of preallocated can_ml_priv for per device struct can_dev_rcv_lists

This patch removes the old method of allocating the per device protocol
specific memory via a netdevice_notifier. This had the drawback, that
the allocation can fail, leading to a lot of null pointer checks in the
code. This also makes the live cycle management of this memory quite
complicated.

This patch switches from the allocating the struct can_dev_rcv_lists in
a NETDEV_REGISTER call to using the dev->ml_priv, which is allocated by
the driver since the previous patch.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

6 files changed, 12 insertions, 39 deletions

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 9e688dc29521..b429550c4cc2 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -746,6 +746,8 @@ struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
         priv = netdev_priv(dev);
         priv->dev = dev;
 
+        dev->ml_priv = (void *)priv + ALIGN(sizeof_priv, NETDEV_ALIGN);
+
         if (echo_skb_max) {
                 priv->echo_skb_max = echo_skb_max;
                 priv->echo_skb = (void *)priv +
diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index 5b2e95425e69..bb6032211043 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -536,6 +536,7 @@ static struct slcan *slc_alloc(void)
 
         dev->base_addr  = i;
         sl = netdev_priv(dev);
+        dev->ml_priv = (void *)sl + ALIGN(sizeof(*sl), NETDEV_ALIGN);
 
         /* Initialize channel control data */
         sl->magic = SLCAN_MAGIC;
diff --git a/drivers/net/can/vcan.c b/drivers/net/can/vcan.c
index 6973ae09a37a..39ca14b0585d 100644
--- a/drivers/net/can/vcan.c
+++ b/drivers/net/can/vcan.c
@@ -153,6 +153,7 @@ static void vcan_setup(struct net_device *dev)
         dev->addr_len           = 0;
         dev->tx_queue_len       = 0;
         dev->flags              = IFF_NOARP;
+        dev->ml_priv            = netdev_priv(dev);
 
         /* set flags according to driver capabilities */
         if (echo)
diff --git a/drivers/net/can/vxcan.c b/drivers/net/can/vxcan.c
index 4c3eed796432..d6ba9426be4d 100644
--- a/drivers/net/can/vxcan.c
+++ b/drivers/net/can/vxcan.c
@@ -147,6 +147,7 @@ static void vxcan_setup(struct net_device *dev)
         dev->flags              = (IFF_NOARP|IFF_ECHO);
         dev->netdev_ops         = &vxcan_netdev_ops;
         dev->needs_free_netdev  = true;
+        dev->ml_priv            = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN);
 }
 
 /* forward declaration for rtnl_create_link() */
diff --git a/include/linux/can/can-ml.h b/include/linux/can/can-ml.h
index 0a9d778de8af..79ccf6bfa232 100644
--- a/include/linux/can/can-ml.h
+++ b/include/linux/can/can-ml.h
@@ -55,7 +55,6 @@ struct can_dev_rcv_lists {
         struct hlist_head rx[RX_MAX];
         struct hlist_head rx_sff[CAN_SFF_RCV_ARRAY_SZ];
         struct hlist_head rx_eff[CAN_EFF_RCV_ARRAY_SZ];
-        int remove_on_zero_entries;
         int entries;
 };
 
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 723299daa04e..6ed85e2f72f0 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -302,10 +302,12 @@ EXPORT_SYMBOL(can_send);
 static struct can_dev_rcv_lists *can_dev_rcv_lists_find(struct net *net,
                                                         struct net_device *dev)
 {
-        if (!dev)
+        if (dev) {
+                struct can_ml_priv *ml_priv = dev->ml_priv;
+                return &ml_priv->dev_rcv_lists;
+        } else {
                 return net->can.rx_alldev_list;
-        else
-                return (struct can_dev_rcv_lists *)dev->ml_priv;
+        }
 }
 
 /**
@@ -561,12 +563,6 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
         if (rcv_lists_stats->rcv_entries > 0)
                 rcv_lists_stats->rcv_entries--;
 
-        /* remove device structure requested by NETDEV_UNREGISTER */
-        if (dev_rcv_lists->remove_on_zero_entries && !dev_rcv_lists->entries) {
-                kfree(dev_rcv_lists);
-                dev->ml_priv = NULL;
-        }
-
  out:
         spin_unlock(&net->can.rcvlists_lock);
 
@@ -788,41 +784,14 @@ static int can_notifier(struct notifier_block *nb, unsigned long msg,
                         void *ptr)
 {
         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
-        struct can_dev_rcv_lists *dev_rcv_lists;
 
         if (dev->type != ARPHRD_CAN)
                 return NOTIFY_DONE;
 
         switch (msg) {
         case NETDEV_REGISTER:
-
-                /* create new dev_rcv_lists for this device */
-                dev_rcv_lists = kzalloc(sizeof(*dev_rcv_lists), GFP_KERNEL);
-                if (!dev_rcv_lists)
-                        return NOTIFY_DONE;
-                BUG_ON(dev->ml_priv);
-                dev->ml_priv = dev_rcv_lists;
-
-                break;
-
-        case NETDEV_UNREGISTER:
-                spin_lock(&dev_net(dev)->can.rcvlists_lock);
-
-                dev_rcv_lists = dev->ml_priv;
-                if (dev_rcv_lists) {
-                        if (dev_rcv_lists->entries)
-                                dev_rcv_lists->remove_on_zero_entries = 1;
-                        else {
-                                kfree(dev_rcv_lists);
-                                dev->ml_priv = NULL;
-                        }
-                } else {
-                        pr_err("can: notifier: receive list not found for dev %s\n",
-                               dev->name);
-                }
-
-                spin_unlock(&dev_net(dev)->can.rcvlists_lock);
-
+                WARN(!dev->ml_priv,
+                     "No CAN mid layer private allocated, please fix your driver and use alloc_candev()!\n");
                 break;
         }