hv_netvsc: untangle the pointer mess

We have the following structures keeping netvsc adapter state:
- struct net_device
- struct net_device_context
- struct netvsc_device
- struct rndis_device
- struct hv_device
and there are pointers/dependencies between them:
- struct net_device_context is contained in struct net_device
- struct hv_device has driver_data pointer which points to
  'struct net_device' OR 'struct netvsc_device' depending on driver's
  state (!).
- struct net_device_context has a pointer to 'struct hv_device'.
- struct netvsc_device has pointers to 'struct hv_device' and
  'struct net_device_context'.
- struct rndis_device has a pointer to 'struct netvsc_device'.

Different functions get different structures as parameters and use these
pointers for traveling. The problem is (in addition to keeping in mind
this complex graph) that some of these structures (struct netvsc_device
and struct rndis_device) are being removed and re-created on mtu change
(as we implement it as re-creation of hyper-v device) so our travel using
these pointers is dangerous.

Simplify this to a the following:
- add struct netvsc_device pointer to struct net_device_context (which is
  a part of struct net_device and thus never disappears)
- remove struct hv_device and struct net_device_context pointers from
  struct netvsc_device
- replace pointer to 'struct netvsc_device' with pointer to
  'struct net_device'.
- always keep 'struct net_device' in hv_device driver_data.

We'll end up with the following 'circular' structure:

net_device:
 [net_device_context] -> netvsc_device -> rndis_device -> net_device
                      -> hv_device -> net_device

On MTU change we'll be removing the 'netvsc_device -> rndis_device'
branch and re-creating it making the synchronization easier.

There is one additional redundant pointer left, it is struct net_device
link in struct netvsc_device, it is going to be removed in a separate
commit.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 33 insertions, 49 deletions

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 5e2017bb93f1..1cd01ad2194f 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -40,7 +40,9 @@
 void netvsc_switch_datapath(struct netvsc_device *nv_dev, bool vf)
 {
 	struct nvsp_message *init_pkt = &nv_dev->channel_init_pkt;
-	struct hv_device *dev = nv_dev->dev;
+	struct net_device *ndev = nv_dev->ndev;
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct hv_device *dev = net_device_ctx->device_ctx;
 
 	memset(init_pkt, 0, sizeof(struct nvsp_message));
 	init_pkt->hdr.msg_type = NVSP_MSG4_TYPE_SWITCH_DATA_PATH;
@@ -62,6 +64,7 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
 {
 	struct netvsc_device *net_device;
 	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
 
 	net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
 	if (!net_device)
@@ -77,7 +80,6 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
 	net_device->destroy = false;
 	atomic_set(&net_device->open_cnt, 0);
 	atomic_set(&net_device->vf_use_cnt, 0);
-	net_device->dev = device;
 	net_device->ndev = ndev;
 	net_device->max_pkt = RNDIS_MAX_PKT_DEFAULT;
 	net_device->pkt_align = RNDIS_PKT_ALIGN_DEFAULT;
@@ -85,7 +87,8 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
 	net_device->vf_netdev = NULL;
 	net_device->vf_inject = false;
 
-	hv_set_drvdata(device, net_device);
+	net_device_ctx->nvdev = net_device;
+
 	return net_device;
 }
 
@@ -97,9 +100,10 @@ static void free_netvsc_device(struct netvsc_device *nvdev)
 
 static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
 {
-	struct netvsc_device *net_device;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct netvsc_device *net_device = net_device_ctx->nvdev;
 
-	net_device = hv_get_drvdata(device);
 	if (net_device && net_device->destroy)
 		net_device = NULL;
 
@@ -108,9 +112,9 @@ static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
 
 static struct netvsc_device *get_inbound_net_device(struct hv_device *device)
 {
-	struct netvsc_device *net_device;
-
-	net_device = hv_get_drvdata(device);
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct netvsc_device *net_device = net_device_ctx->nvdev;
 
 	if (!net_device)
 		goto get_in_err;
@@ -124,11 +128,13 @@ get_in_err:
 }
 
 
-static int netvsc_destroy_buf(struct netvsc_device *net_device)
+static int netvsc_destroy_buf(struct hv_device *device)
 {
 	struct nvsp_message *revoke_packet;
 	int ret = 0;
-	struct net_device *ndev = net_device->ndev;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct netvsc_device *net_device = net_device_ctx->nvdev;
 
 	/*
 	 * If we got a section count, it means we received a
@@ -146,7 +152,7 @@ static int netvsc_destroy_buf(struct netvsc_device *net_device)
 		revoke_packet->msg.v1_msg.
 		revoke_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;
 
-		ret = vmbus_sendpacket(net_device->dev->channel,
+		ret = vmbus_sendpacket(device->channel,
 				       revoke_packet,
 				       sizeof(struct nvsp_message),
 				       (unsigned long)revoke_packet,
@@ -164,8 +170,8 @@ static int netvsc_destroy_buf(struct netvsc_device *net_device)
 
 	/* Teardown the gpadl on the vsp end */
 	if (net_device->recv_buf_gpadl_handle) {
-		ret = vmbus_teardown_gpadl(net_device->dev->channel,
-			   net_device->recv_buf_gpadl_handle);
+		ret = vmbus_teardown_gpadl(device->channel,
+					   net_device->recv_buf_gpadl_handle);
 
 		/* If we failed here, we might as well return and have a leak
 		 * rather than continue and a bugchk
@@ -206,7 +212,7 @@ static int netvsc_destroy_buf(struct netvsc_device *net_device)
 		revoke_packet->msg.v1_msg.revoke_send_buf.id =
 			NETVSC_SEND_BUFFER_ID;
 
-		ret = vmbus_sendpacket(net_device->dev->channel,
+		ret = vmbus_sendpacket(device->channel,
 				       revoke_packet,
 				       sizeof(struct nvsp_message),
 				       (unsigned long)revoke_packet,
@@ -222,7 +228,7 @@ static int netvsc_destroy_buf(struct netvsc_device *net_device)
 	}
 	/* Teardown the gpadl on the vsp end */
 	if (net_device->send_buf_gpadl_handle) {
-		ret = vmbus_teardown_gpadl(net_device->dev->channel,
+		ret = vmbus_teardown_gpadl(device->channel,
 					   net_device->send_buf_gpadl_handle);
 
 		/* If we failed here, we might as well return and have a leak
@@ -434,7 +440,7 @@ static int netvsc_init_buf(struct hv_device *device)
 	goto exit;
 
 cleanup:
-	netvsc_destroy_buf(net_device);
+	netvsc_destroy_buf(device);
 
 exit:
 	return ret;
@@ -565,9 +571,9 @@ cleanup:
 	return ret;
 }
 
-static void netvsc_disconnect_vsp(struct netvsc_device *net_device)
+static void netvsc_disconnect_vsp(struct hv_device *device)
 {
-	netvsc_destroy_buf(net_device);
+	netvsc_destroy_buf(device);
 }
 
 /*
@@ -575,24 +581,13 @@ static void netvsc_disconnect_vsp(struct netvsc_device *net_device)
  */
 int netvsc_device_remove(struct hv_device *device)
 {
-	struct netvsc_device *net_device;
-	unsigned long flags;
-
-	net_device = hv_get_drvdata(device);
-
-	netvsc_disconnect_vsp(net_device);
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
+	struct netvsc_device *net_device = net_device_ctx->nvdev;
 
-	/*
-	 * Since we have already drained, we don't need to busy wait
-	 * as was done in final_release_stor_device()
-	 * Note that we cannot set the ext pointer to NULL until
-	 * we have drained - to drain the outgoing packets, we need to
-	 * allow incoming packets.
-	 */
+	netvsc_disconnect_vsp(device);
 
-	spin_lock_irqsave(&device->channel->inbound_lock, flags);
-	hv_set_drvdata(device, NULL);
-	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
+	net_device_ctx->nvdev = NULL;
 
 	/*
 	 * At this point, no one should be accessing net_device
@@ -640,12 +635,11 @@ static void netvsc_send_completion(struct netvsc_device *net_device,
 {
 	struct nvsp_message *nvsp_packet;
 	struct hv_netvsc_packet *nvsc_packet;
-	struct net_device *ndev;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct net_device_context *net_device_ctx = netdev_priv(ndev);
 	u32 send_index;
 	struct sk_buff *skb;
 
-	ndev = net_device->ndev;
-
 	nvsp_packet = (struct nvsp_message *)((unsigned long)packet +
 			(packet->offset8 << 3));
 
@@ -690,7 +684,7 @@ static void netvsc_send_completion(struct netvsc_device *net_device,
 			wake_up(&net_device->wait_drain);
 
 		if (netif_tx_queue_stopped(netdev_get_tx_queue(ndev, q_idx)) &&
-		    !net_device->nd_ctx->start_remove &&
+		    !net_device_ctx->start_remove &&
 		    (hv_ringbuf_avail_percent(&channel->outbound) >
 		     RING_AVAIL_PERCENT_HIWATER || queue_sends < 1))
 				netif_tx_wake_queue(netdev_get_tx_queue(
@@ -1264,17 +1258,7 @@ int netvsc_device_add(struct hv_device *device, void *additional_info)
 
 	net_device->ring_size = ring_size;
 
-	/*
-	 * Coming into this function, struct net_device * is
-	 * registered as the driver private data.
-	 * In alloc_net_device(), we register struct netvsc_device *
-	 * as the driver private data and stash away struct net_device *
-	 * in struct netvsc_device *.
-	 */
-	ndev = net_device->ndev;
-
-	/* Add netvsc_device context to netvsc_device */
-	net_device->nd_ctx = netdev_priv(ndev);
+	ndev = hv_get_drvdata(device);
 
 	/* Initialize the NetVSC channel extension */
 	init_completion(&net_device->channel_init_wait);