netdevsim: Add multi-queue support

Currently netdevsim only supports a single queue per port, which is
insufficient for testing multi-queue TC schedulers e.g. sch_mq.  Extend
the current sysfs interface so that users can create ports with multiple
queues:

$ echo "[ID] [PORT_COUNT] [NUM_QUEUES]" > /sys/bus/netdevsim/new_device

As an example, echoing "2 4 8" creates 4 ports, with 8 queues per port.
Note, this is compatible with the current interface, with default number
of queues set to 1.  For example, echoing "2 4" creates 4 ports with 1
queue per port; echoing "2" simply creates 1 port with 1 queue.
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netdevsim/bus.c

@@ -262,29 +262,31 @@ static struct device_type nsim_bus_dev_type = {
 };
 
 static struct nsim_bus_dev *
-nsim_bus_dev_new(unsigned int id, unsigned int port_count);
+nsim_bus_dev_new(unsigned int id, unsigned int port_count, unsigned int num_queues);
 
 static ssize_t
 new_device_store(struct bus_type *bus, const char *buf, size_t count)
 {
+	unsigned int id, port_count, num_queues;
 	struct nsim_bus_dev *nsim_bus_dev;
-	unsigned int port_count;
-	unsigned int id;
 	int err;
 
-	err = sscanf(buf, "%u %u", &id, &port_count);
+	err = sscanf(buf, "%u %u %u", &id, &port_count, &num_queues);
 	switch (err) {
 	case 1:
 		port_count = 1;
 		fallthrough;
 	case 2:
+		num_queues = 1;
+		fallthrough;
+	case 3:
 		if (id > INT_MAX) {
 			pr_err("Value of \"id\" is too big.\n");
 			return -EINVAL;
 		}
 		break;
 	default:
-		pr_err("Format for adding new device is \"id port_count\" (uint uint).\n");
+		pr_err("Format for adding new device is \"id port_count num_queues\" (uint uint unit).\n");
 		return -EINVAL;
 	}
 
@@ -295,7 +297,7 @@ new_device_store(struct bus_type *bus, const char *buf, size_t count)
 		goto err;
 	}
 
-	nsim_bus_dev = nsim_bus_dev_new(id, port_count);
+	nsim_bus_dev = nsim_bus_dev_new(id, port_count, num_queues);
 	if (IS_ERR(nsim_bus_dev)) {
 		err = PTR_ERR(nsim_bus_dev);
 		goto err;
@@ -397,7 +399,7 @@ static struct bus_type nsim_bus = {
 #define NSIM_BUS_DEV_MAX_VFS 4
 
 static struct nsim_bus_dev *
-nsim_bus_dev_new(unsigned int id, unsigned int port_count)
+nsim_bus_dev_new(unsigned int id, unsigned int port_count, unsigned int num_queues)
 {
 	struct nsim_bus_dev *nsim_bus_dev;
 	int err;
@@ -413,6 +415,7 @@ nsim_bus_dev_new(unsigned int id, unsigned int port_count)
 	nsim_bus_dev->dev.bus = &nsim_bus;
 	nsim_bus_dev->dev.type = &nsim_bus_dev_type;
 	nsim_bus_dev->port_count = port_count;
+	nsim_bus_dev->num_queues = num_queues;
 	nsim_bus_dev->initial_net = current->nsproxy->net_ns;
 	nsim_bus_dev->max_vfs = NSIM_BUS_DEV_MAX_VFS;
 	mutex_init(&nsim_bus_dev->nsim_bus_reload_lock);

drivers/net/netdevsim/netdev.c

@@ -347,7 +347,8 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
 	struct netdevsim *ns;
 	int err;
 
-	dev = alloc_netdev(sizeof(*ns), "eth%d", NET_NAME_UNKNOWN, nsim_setup);
+	dev = alloc_netdev_mq(sizeof(*ns), "eth%d", NET_NAME_UNKNOWN, nsim_setup,
+			      nsim_dev->nsim_bus_dev->num_queues);
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
@@ -392,7 +393,8 @@ void nsim_destroy(struct netdevsim *ns)
 static int nsim_validate(struct nlattr *tb[], struct nlattr *data[],
 			 struct netlink_ext_ack *extack)
 {
-	NL_SET_ERR_MSG_MOD(extack, "Please use: echo \"[ID] [PORT_COUNT]\" > /sys/bus/netdevsim/new_device");
+	NL_SET_ERR_MSG_MOD(extack,
+			   "Please use: echo \"[ID] [PORT_COUNT] [NUM_QUEUES]\" > /sys/bus/netdevsim/new_device");
 	return -EOPNOTSUPP;
 }
 

drivers/net/netdevsim/netdevsim.h

@@ -352,6 +352,7 @@ struct nsim_bus_dev {
 	struct device dev;
 	struct list_head list;
 	unsigned int port_count;
+	unsigned int num_queues; /* Number of queues for each port on this bus */
 	struct net *initial_net; /* Purpose of this is to carry net pointer
 				  * during the probe time only.
 				  */