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Subject[PATCH v2 12/18] IB/umad: increase maximum devices supported
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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>
---
drivers/infiniband/core/user_mad.c | 50 ++++++++++++++++++++++++++++++++----
1 files changed, 44 insertions(+), 6 deletions(-)
diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 5a66bd0..7fc1e51 100644
--- 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 oflo_maj;
+static DECLARE_BITMAP(oflo_map, IB_UMAD_MAX_PORTS);
+static int find_oflo_devnum(void)
+{
+ int ret;
+
+ if (!oflo_maj) {
+ ret = alloc_chrdev_region(&oflo_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(oflo_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_oflo_devnum();
+ if (devnum < 0)
+ return -1;
+
+ spin_lock(&port_lock);
+ port->dev_num = devnum + IB_UMAD_MAX_PORTS;
+ base = devnum + oflo_maj;
+ set_bit(devnum, oflo_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, oflo_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, oflo_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 (oflo_maj)
+ unregister_chrdev_region(oflo_maj, IB_UMAD_MAX_PORTS * 2);
}

module_init(ib_umad_init);


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