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, 21 insertions, 30 deletions

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 01de2dcef170..a33a1c92d489 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -70,7 +70,7 @@ static void do_set_multicast(struct work_struct *w)
 	struct netvsc_device *nvdev;
 	struct rndis_device *rdev;
 
-	nvdev = hv_get_drvdata(ndevctx->device_ctx);
+	nvdev = ndevctx->nvdev;
 	if (nvdev == NULL || nvdev->ndev == NULL)
 		return;
 
@@ -99,7 +99,7 @@ static int netvsc_open(struct net_device *net)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(net);
 	struct hv_device *device_obj = net_device_ctx->device_ctx;
-	struct netvsc_device *nvdev;
+	struct netvsc_device *nvdev = net_device_ctx->nvdev;
 	struct rndis_device *rdev;
 	int ret = 0;
 
@@ -114,7 +114,6 @@ static int netvsc_open(struct net_device *net)
 
 	netif_tx_wake_all_queues(net);
 
-	nvdev = hv_get_drvdata(device_obj);
 	rdev = nvdev->extension;
 	if (!rdev->link_state)
 		netif_carrier_on(net);
@@ -126,7 +125,7 @@ static int netvsc_close(struct net_device *net)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(net);
 	struct hv_device *device_obj = net_device_ctx->device_ctx;
-	struct netvsc_device *nvdev = hv_get_drvdata(device_obj);
+	struct netvsc_device *nvdev = net_device_ctx->nvdev;
 	int ret;
 	u32 aread, awrite, i, msec = 10, retry = 0, retry_max = 20;
 	struct vmbus_channel *chn;
@@ -205,8 +204,7 @@ static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
 			void *accel_priv, select_queue_fallback_t fallback)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(ndev);
-	struct hv_device *hdev =  net_device_ctx->device_ctx;
-	struct netvsc_device *nvsc_dev = hv_get_drvdata(hdev);
+	struct netvsc_device *nvsc_dev = net_device_ctx->nvdev;
 	u32 hash;
 	u16 q_idx = 0;
 
@@ -580,7 +578,6 @@ void netvsc_linkstatus_callback(struct hv_device *device_obj,
 	struct rndis_indicate_status *indicate = &resp->msg.indicate_status;
 	struct net_device *net;
 	struct net_device_context *ndev_ctx;
-	struct netvsc_device *net_device;
 	struct netvsc_reconfig *event;
 	unsigned long flags;
 
@@ -590,8 +587,7 @@ void netvsc_linkstatus_callback(struct hv_device *device_obj,
 	    indicate->status != RNDIS_STATUS_MEDIA_DISCONNECT)
 		return;
 
-	net_device = hv_get_drvdata(device_obj);
-	net = net_device->ndev;
+	net = hv_get_drvdata(device_obj);
 
 	if (!net || net->reg_state != NETREG_REGISTERED)
 		return;
@@ -659,16 +655,15 @@ int netvsc_recv_callback(struct hv_device *device_obj,
 				struct vmbus_channel *channel,
 				u16 vlan_tci)
 {
-	struct net_device *net;
-	struct net_device_context *net_device_ctx;
+	struct net_device *net = hv_get_drvdata(device_obj);
+	struct net_device_context *net_device_ctx = netdev_priv(net);
 	struct sk_buff *skb;
 	struct sk_buff *vf_skb;
 	struct netvsc_stats *rx_stats;
-	struct netvsc_device *netvsc_dev = hv_get_drvdata(device_obj);
+	struct netvsc_device *netvsc_dev = net_device_ctx->nvdev;
 	u32 bytes_recvd = packet->total_data_buflen;
 	int ret = 0;
 
-	net = netvsc_dev->ndev;
 	if (!net || net->reg_state != NETREG_REGISTERED)
 		return NVSP_STAT_FAIL;
 
@@ -743,8 +738,7 @@ static void netvsc_get_channels(struct net_device *net,
 				struct ethtool_channels *channel)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(net);
-	struct hv_device *dev = net_device_ctx->device_ctx;
-	struct netvsc_device *nvdev = hv_get_drvdata(dev);
+	struct netvsc_device *nvdev = net_device_ctx->nvdev;
 
 	if (nvdev) {
 		channel->max_combined	= nvdev->max_chn;
@@ -757,7 +751,7 @@ static int netvsc_set_channels(struct net_device *net,
 {
 	struct net_device_context *net_device_ctx = netdev_priv(net);
 	struct hv_device *dev = net_device_ctx->device_ctx;
-	struct netvsc_device *nvdev = hv_get_drvdata(dev);
+	struct netvsc_device *nvdev = net_device_ctx->nvdev;
 	struct netvsc_device_info device_info;
 	u32 num_chn;
 	u32 max_chn;
@@ -798,9 +792,6 @@ static int netvsc_set_channels(struct net_device *net,
 
 	nvdev->num_chn = channels->combined_count;
 
-	net_device_ctx->device_ctx = dev;
-	hv_set_drvdata(dev, net);
-
 	memset(&device_info, 0, sizeof(device_info));
 	device_info.num_chn = nvdev->num_chn; /* passed to RNDIS */
 	device_info.ring_size = ring_size;
@@ -815,7 +806,7 @@ static int netvsc_set_channels(struct net_device *net,
 		goto recover;
 	}
 
-	nvdev = hv_get_drvdata(dev);
+	nvdev = net_device_ctx->nvdev;
 
 	ret = netif_set_real_num_tx_queues(net, nvdev->num_chn);
 	if (ret) {
@@ -908,8 +899,8 @@ static int netvsc_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
 static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 {
 	struct net_device_context *ndevctx = netdev_priv(ndev);
-	struct hv_device *hdev =  ndevctx->device_ctx;
-	struct netvsc_device *nvdev = hv_get_drvdata(hdev);
+	struct netvsc_device *nvdev = ndevctx->nvdev;
+	struct hv_device *hdev = ndevctx->device_ctx;
 	struct netvsc_device_info device_info;
 	int limit = ETH_DATA_LEN;
 	u32 num_chn;
@@ -935,9 +926,6 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 
 	ndev->mtu = mtu;
 
-	ndevctx->device_ctx = hdev;
-	hv_set_drvdata(hdev, ndev);
-
 	memset(&device_info, 0, sizeof(device_info));
 	device_info.ring_size = ring_size;
 	device_info.num_chn = num_chn;
@@ -1076,7 +1064,7 @@ static void netvsc_link_change(struct work_struct *w)
 	if (ndev_ctx->start_remove)
 		goto out_unlock;
 
-	net_device = hv_get_drvdata(ndev_ctx->device_ctx);
+	net_device = ndev_ctx->nvdev;
 	rdev = net_device->extension;
 	net = net_device->ndev;
 
@@ -1201,7 +1189,7 @@ static struct netvsc_device *get_netvsc_device(char *mac)
 	if (netvsc_ctx == NULL)
 		return NULL;
 
-	return hv_get_drvdata(netvsc_ctx->device_ctx);
+	return netvsc_ctx->nvdev;
 }
 
 static int netvsc_register_vf(struct net_device *vf_netdev)
@@ -1407,7 +1395,7 @@ static int netvsc_probe(struct hv_device *dev,
 	}
 	memcpy(net->dev_addr, device_info.mac_adr, ETH_ALEN);
 
-	nvdev = hv_get_drvdata(dev);
+	nvdev = net_device_ctx->nvdev;
 	netif_set_real_num_tx_queues(net, nvdev->num_chn);
 	netif_set_real_num_rx_queues(net, nvdev->num_chn);
 
@@ -1429,8 +1417,7 @@ static int netvsc_remove(struct hv_device *dev)
 	struct net_device_context *ndev_ctx;
 	struct netvsc_device *net_device;
 
-	net_device = hv_get_drvdata(dev);
-	net = net_device->ndev;
+	net = hv_get_drvdata(dev);
 
 	if (net == NULL) {
 		dev_err(&dev->device, "No net device to remove\n");
@@ -1439,6 +1426,8 @@ static int netvsc_remove(struct hv_device *dev)
 
 
 	ndev_ctx = netdev_priv(net);
+	net_device = ndev_ctx->nvdev;
+
 	ndev_ctx->start_remove = true;
 
 	cancel_delayed_work_sync(&ndev_ctx->dwork);
@@ -1455,6 +1444,8 @@ static int netvsc_remove(struct hv_device *dev)
 	 */
 	rndis_filter_device_remove(dev);
 
+	hv_set_drvdata(dev, NULL);
+
 	netvsc_free_netdev(net);
 	return 0;
 }