[PATCH net-next] Name NICs based on vmbus offer and enable async probe by default

[Haiyang Zhang]

Previously the async probing caused NIC naming in random order.

The patch adds a dev_num field in vmbus channel structure. Itâs assigned
to the first available number when the channel is offered. So netvsc can
use it for NIC naming based on channel offer sequence. Now we re-enable
the async probing mode by default for faster probing.

Also added a modules parameter, probe_type, to set sync probing mode if
a user wants to.

Fixes: af0a5646cb8d ("use the new async probing feature for the hyperv drivers")
Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
---
 drivers/hv/channel_mgmt.c       | 46 +++++++++++++++++++++++++++++++++++++++--
 drivers/net/hyperv/netvsc_drv.c | 33 ++++++++++++++++++++++++++---
 include/linux/hyperv.h          |  4 ++++
 3 files changed, 78 insertions(+), 5 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index addcef5..ab7c05b 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -304,6 +304,8 @@ bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
 
 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
 
+#define HV_DEV_NUM_INVALID (-1)
+
 /*
  * alloc_channel - Allocate and initialize a vmbus channel object
  */
@@ -315,6 +317,8 @@ static struct vmbus_channel *alloc_channel(void)
 	if (!channel)
 		return NULL;
 
+	channel->dev_num = HV_DEV_NUM_INVALID;
+
 	spin_lock_init(&channel->lock);
 	init_completion(&channel->rescind_event);
 
@@ -533,6 +537,42 @@ static void vmbus_add_channel_work(struct work_struct *work)
 }
 
 /*
+ * Get the first available device number of its type, then
+ * record it in the channel structure.
+ */
+static void hv_set_devnum(struct vmbus_channel *newchannel)
+{
+	struct vmbus_channel *channel;
+	unsigned int i = 0;
+	bool found;
+
+	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
+
+	/* Only HV_NIC uses this number for now */
+	if (hv_get_dev_type(newchannel) != HV_NIC)
+		return;
+
+next:
+	found = false;
+
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (i == channel->dev_num &&
+		    guid_equal(&channel->offermsg.offer.if_type,
+			       &newchannel->offermsg.offer.if_type)) {
+			found = true;
+			break;
+		}
+	}
+
+	if (found) {
+		i++;
+		goto next;
+	}
+
+	newchannel->dev_num = i;
+}
+
+/*
  * vmbus_process_offer - Process the offer by creating a channel/device
  * associated with this offer
  */
@@ -561,10 +601,12 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 		}
 	}
 
-	if (fnew)
+	if (fnew) {
+		hv_set_devnum(newchannel);
+
 		list_add_tail(&newchannel->listentry,
 			      &vmbus_connection.chn_list);
-	else {
+	} else {
 		/*
 		 * Check to see if this is a valid sub-channel.
 		 */
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index afdcc56..af53690 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -57,6 +57,10 @@
 module_param(debug, int, 0444);
 MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
 
+static unsigned int probe_type __ro_after_init = PROBE_PREFER_ASYNCHRONOUS;
+module_param(probe_type, uint, 0444);
+MODULE_PARM_DESC(probe_type, "Probe type: 1=async(default), 2=sync");
+
 static LIST_HEAD(netvsc_dev_list);
 
 static void netvsc_change_rx_flags(struct net_device *net, int change)
@@ -2233,10 +2237,19 @@ static int netvsc_probe(struct hv_device *dev,
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device_info *device_info = NULL;
 	struct netvsc_device *nvdev;
+	char name[IFNAMSIZ];
 	int ret = -ENOMEM;
 
-	net = alloc_etherdev_mq(sizeof(struct net_device_context),
-				VRSS_CHANNEL_MAX);
+	if (probe_type == PROBE_PREFER_ASYNCHRONOUS) {
+		snprintf(name, IFNAMSIZ, "eth%d", dev->channel->dev_num);
+		net = alloc_netdev_mqs(sizeof(struct net_device_context), name,
+				       NET_NAME_ENUM, ether_setup,
+				       VRSS_CHANNEL_MAX, VRSS_CHANNEL_MAX);
+	} else {
+		net = alloc_etherdev_mq(sizeof(struct net_device_context),
+					VRSS_CHANNEL_MAX);
+	}
+
 	if (!net)
 		goto no_net;
 
@@ -2323,6 +2336,14 @@ static int netvsc_probe(struct hv_device *dev,
 		net->max_mtu = ETH_DATA_LEN;
 
 	ret = register_netdevice(net);
+
+	if (ret == -EEXIST) {
+		pr_info("NIC name %s exists, request another name.\n",
+			net->name);
+		strlcpy(net->name, "eth%d", IFNAMSIZ);
+		ret = register_netdevice(net);
+	}
+
 	if (ret != 0) {
 		pr_err("Unable to register netdev.\n");
 		goto register_failed;
@@ -2407,7 +2428,7 @@ static int netvsc_remove(struct hv_device *dev)
 	.probe = netvsc_probe,
 	.remove = netvsc_remove,
 	.driver = {
-		.probe_type = PROBE_FORCE_SYNCHRONOUS,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
 };
 
@@ -2473,6 +2494,12 @@ static int __init netvsc_drv_init(void)
 	}
 	netvsc_ring_bytes = ring_size * PAGE_SIZE;
 
+	if (probe_type != PROBE_PREFER_ASYNCHRONOUS)
+		probe_type = PROBE_FORCE_SYNCHRONOUS;
+
+	netvsc_drv.driver.probe_type = probe_type;
+	pr_info("probe_type: %u\n", probe_type);
+
 	ret = vmbus_driver_register(&netvsc_drv);
 	if (ret)
 		return ret;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 6256cc3..12fc5ea 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -841,6 +841,10 @@ struct vmbus_channel {
 	 */
 	struct vmbus_channel *primary_channel;
 	/*
+	 * Used for device naming based on channel offer sequence.
+	 */
+	int dev_num;
+	/*
 	 * Support per-channel state for use by vmbus drivers.
 	 */
 	void *per_channel_state;
-- 
1.8.3.1