IB/core: Increase number of char device minors

There is a need to increase number of possible char devices to support
large number of SR-IOV instances. The current limit is in the range of
64-128 devices/ports. Increase it to support up to 1024.

The patch performs the following steps to refactor the code:
1. Removes the split bitmap for fixed and overflow dev numbers.
2. Pre-allocates the non-legacy major number range during driver
   initialization, choosen for simplicity.
3. Add new define (RDMA_MAX_PORTS) that is shared between all drivers.
   This is the maximum total number of ports on all struct ib_devices.
4. Set RDMA_MAX_PORTS to 1024.

Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 34 insertions, 56 deletions

diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 9e06f810bbeb..899102ad6bb6 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -62,11 +62,14 @@ MODULE_LICENSE("Dual BSD/GPL");
 enum {
 	IB_UVERBS_MAJOR       = 231,
 	IB_UVERBS_BASE_MINOR  = 192,
-	IB_UVERBS_MAX_DEVICES = 32
+	IB_UVERBS_MAX_DEVICES = RDMA_MAX_PORTS,
+	IB_UVERBS_NUM_FIXED_MINOR = 32,
+	IB_UVERBS_NUM_DYNAMIC_MINOR = IB_UVERBS_MAX_DEVICES - IB_UVERBS_NUM_FIXED_MINOR,
 };
 
 #define IB_UVERBS_BASE_DEV	MKDEV(IB_UVERBS_MAJOR, IB_UVERBS_BASE_MINOR)
 
+static dev_t dynamic_uverbs_dev;
 static struct class *uverbs_class;
 
 static DECLARE_BITMAP(dev_map, IB_UVERBS_MAX_DEVICES);
@@ -1004,34 +1007,6 @@ static DEVICE_ATTR(abi_version, S_IRUGO, show_dev_abi_version, NULL);
 static CLASS_ATTR_STRING(abi_version, S_IRUGO,
 			 __stringify(IB_USER_VERBS_ABI_VERSION));
 
-static dev_t overflow_maj;
-static DECLARE_BITMAP(overflow_map, IB_UVERBS_MAX_DEVICES);
-
-/*
- * If we have more than IB_UVERBS_MAX_DEVICES, dynamically overflow by
- * requesting a new major number and doubling the number of max devices we
- * support. It's stupid, but simple.
- */
-static int find_overflow_devnum(void)
-{
-	int ret;
-
-	if (!overflow_maj) {
-		ret = alloc_chrdev_region(&overflow_maj, 0, IB_UVERBS_MAX_DEVICES,
-					  "infiniband_verbs");
-		if (ret) {
-			pr_err("user_verbs: couldn't register dynamic device number\n");
-			return ret;
-		}
-	}
-
-	ret = find_first_zero_bit(overflow_map, IB_UVERBS_MAX_DEVICES);
-	if (ret >= IB_UVERBS_MAX_DEVICES)
-		return -1;
-
-	return ret;
-}
-
 static void ib_uverbs_add_one(struct ib_device *device)
 {
 	int devnum;
@@ -1062,19 +1037,14 @@ static void ib_uverbs_add_one(struct ib_device *device)
 	INIT_LIST_HEAD(&uverbs_dev->uverbs_events_file_list);
 
 	devnum = find_first_zero_bit(dev_map, IB_UVERBS_MAX_DEVICES);
-	if (devnum >= IB_UVERBS_MAX_DEVICES) {
-		devnum = find_overflow_devnum();
-		if (devnum < 0)
-			goto err;
-
-		uverbs_dev->devnum = devnum + IB_UVERBS_MAX_DEVICES;
-		base = devnum + overflow_maj;
-		set_bit(devnum, overflow_map);
-	} else {
-		uverbs_dev->devnum = devnum;
-		base = devnum + IB_UVERBS_BASE_DEV;
-		set_bit(devnum, dev_map);
-	}
+	if (devnum >= IB_UVERBS_MAX_DEVICES)
+		goto err;
+	uverbs_dev->devnum = devnum;
+	set_bit(devnum, dev_map);
+	if (devnum >= IB_UVERBS_NUM_FIXED_MINOR)
+		base = dynamic_uverbs_dev + devnum - IB_UVERBS_NUM_FIXED_MINOR;
+	else
+		base = IB_UVERBS_BASE_DEV + devnum;
 
 	rcu_assign_pointer(uverbs_dev->ib_dev, device);
 	uverbs_dev->num_comp_vectors = device->num_comp_vectors;
@@ -1119,10 +1089,7 @@ err_class:
 
 err_cdev:
 	cdev_del(&uverbs_dev->cdev);
-	if (uverbs_dev->devnum < IB_UVERBS_MAX_DEVICES)
-		clear_bit(devnum, dev_map);
-	else
-		clear_bit(devnum, overflow_map);
+	clear_bit(devnum, dev_map);
 
 err:
 	if (atomic_dec_and_test(&uverbs_dev->refcount))
@@ -1214,11 +1181,7 @@ static void ib_uverbs_remove_one(struct ib_device *device, void *client_data)
 	dev_set_drvdata(uverbs_dev->dev, NULL);
 	device_destroy(uverbs_class, uverbs_dev->cdev.dev);
 	cdev_del(&uverbs_dev->cdev);
-
-	if (uverbs_dev->devnum < IB_UVERBS_MAX_DEVICES)
-		clear_bit(uverbs_dev->devnum, dev_map);
-	else
-		clear_bit(uverbs_dev->devnum - IB_UVERBS_MAX_DEVICES, overflow_map);
+	clear_bit(uverbs_dev->devnum, dev_map);
 
 	if (device->disassociate_ucontext) {
 		/* We disassociate HW resources and immediately return.
@@ -1260,13 +1223,22 @@ static int __init ib_uverbs_init(void)
 {
 	int ret;
 
-	ret = register_chrdev_region(IB_UVERBS_BASE_DEV, IB_UVERBS_MAX_DEVICES,
+	ret = register_chrdev_region(IB_UVERBS_BASE_DEV,
+				     IB_UVERBS_NUM_FIXED_MINOR,
 				     "infiniband_verbs");
 	if (ret) {
 		pr_err("user_verbs: couldn't register device number\n");
 		goto out;
 	}
 
+	ret = alloc_chrdev_region(&dynamic_uverbs_dev, 0,
+				  IB_UVERBS_NUM_DYNAMIC_MINOR,
+				  "infiniband_verbs");
+	if (ret) {
+		pr_err("couldn't register dynamic device number\n");
+		goto out_alloc;
+	}
+
 	uverbs_class = class_create(THIS_MODULE, "infiniband_verbs");
 	if (IS_ERR(uverbs_class)) {
 		ret = PTR_ERR(uverbs_class);
@@ -1294,7 +1266,12 @@ out_class:
 	class_destroy(uverbs_class);
 
 out_chrdev:
-	unregister_chrdev_region(IB_UVERBS_BASE_DEV, IB_UVERBS_MAX_DEVICES);
+	unregister_chrdev_region(dynamic_uverbs_dev,
+				 IB_UVERBS_NUM_DYNAMIC_MINOR);
+
+out_alloc:
+	unregister_chrdev_region(IB_UVERBS_BASE_DEV,
+				 IB_UVERBS_NUM_FIXED_MINOR);
 
 out:
 	return ret;
@@ -1304,9 +1281,10 @@ static void __exit ib_uverbs_cleanup(void)
 {
 	ib_unregister_client(&uverbs_client);
 	class_destroy(uverbs_class);
-	unregister_chrdev_region(IB_UVERBS_BASE_DEV, IB_UVERBS_MAX_DEVICES);
-	if (overflow_maj)
-		unregister_chrdev_region(overflow_maj, IB_UVERBS_MAX_DEVICES);
+	unregister_chrdev_region(IB_UVERBS_BASE_DEV,
+				 IB_UVERBS_NUM_FIXED_MINOR);
+	unregister_chrdev_region(dynamic_uverbs_dev,
+				 IB_UVERBS_NUM_DYNAMIC_MINOR);
 }
 
 module_init(ib_uverbs_init);