IB/umad: Increase maximum devices supported

Some large systems may support more than IB_UMAD_MAX_PORTS
(currently 64).

This change allows us to support more ports in a backwards-compatible
manner.  The first IB_UMAD_MAX_PORTS keep the same major/minor device
numbers they've always had.

If there are more than IB_UMAD_MAX_PORTS, we then dynamically request
a new major device number (new minors start at 0).

Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 5a66bd062389fe60fb69be6dc32607b7f1818896..57818aea99677e167db34d0fcba0af4fbf863b00 100644 (file)
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -971,6 +971,28 @@ static ssize_t show_abi_version(struct class *class, char *buf)
 }
 static CLASS_ATTR(abi_version, S_IRUGO, show_abi_version, NULL);
 
+static dev_t overflow_maj;
+static DECLARE_BITMAP(overflow_map, IB_UMAD_MAX_PORTS);
+static int find_overflow_devnum(void)
+{
+       int ret;
+
+       if (!overflow_maj) {
+               ret = alloc_chrdev_region(&overflow_maj, 0, IB_UMAD_MAX_PORTS * 2,
+                                         "infiniband_mad");
+               if (ret) {
+                       printk(KERN_ERR "user_mad: couldn't register dynamic device number\n");
+                       return ret;
+               }
+       }
+
+       ret = find_first_zero_bit(overflow_map, IB_UMAD_MAX_PORTS);
+       if (ret >= IB_UMAD_MAX_PORTS)
+               return -1;
+
+       return ret;
+}
+
 static int ib_umad_init_port(struct ib_device *device, int port_num,
                             struct ib_umad_port *port)
 {
@@ -981,11 +1003,19 @@ static int ib_umad_init_port(struct ib_device *device, int port_num,
        devnum = find_first_zero_bit(dev_map, IB_UMAD_MAX_PORTS);
        if (devnum >= IB_UMAD_MAX_PORTS) {
                spin_unlock(&port_lock);
-               return -1;
+               devnum = find_overflow_devnum();
+               if (devnum < 0)
+                       return -1;
+
+               spin_lock(&port_lock);
+               port->dev_num = devnum + IB_UMAD_MAX_PORTS;
+               base = devnum + overflow_maj;
+               set_bit(devnum, overflow_map);
+       } else {
+               port->dev_num = devnum;
+               base = devnum + base_dev;
+               set_bit(devnum, dev_map);
        }
-       port->dev_num = devnum;
-       base = devnum + base_dev;
-       set_bit(devnum, dev_map);
        spin_unlock(&port_lock);
 
        port->ib_dev   = device;
@@ -1042,7 +1072,10 @@ err_dev:
 
 err_cdev:
        cdev_del(&port->cdev);
-       clear_bit(devnum, dev_map);
+       if (port->dev_num < IB_UMAD_MAX_PORTS)
+               clear_bit(devnum, dev_map);
+       else
+               clear_bit(devnum, overflow_map);
 
        return -1;
 }
@@ -1079,7 +1112,10 @@ static void ib_umad_kill_port(struct ib_umad_port *port)
 
        mutex_unlock(&port->file_mutex);
 
-       clear_bit(port->dev_num, dev_map);
+       if (port->dev_num < IB_UMAD_MAX_PORTS)
+               clear_bit(port->dev_num, dev_map);
+       else
+               clear_bit(port->dev_num - IB_UMAD_MAX_PORTS, overflow_map);
 }
 
 static void ib_umad_add_one(struct ib_device *device)
@@ -1187,6 +1223,8 @@ static void __exit ib_umad_cleanup(void)
        ib_unregister_client(&umad_client);
        class_destroy(umad_class);
        unregister_chrdev_region(base_dev, IB_UMAD_MAX_PORTS * 2);
+       if (overflow_maj)
+               unregister_chrdev_region(overflow_maj, IB_UMAD_MAX_PORTS * 2);
 }
 
 module_init(ib_umad_init);