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From: Alex Chiang on 2 Feb 2010 14:20
Some large systems may support more than IB_UCM_MAX_DEVICES
(currently 32).

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

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

Signed-off-by: Alex Chiang <achiang(a)hp.com>
---

drivers/infiniband/core/ucm.c | 53 +++++++++++++++++++++++++++++++++++------
1 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
index 06c50d8..1203ca4 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -1215,7 +1215,10 @@ static void ib_ucm_release_dev(struct device *dev)

ucm_dev = container_of(dev, struct ib_ucm_device, dev);
cdev_del(&ucm_dev->cdev);
- clear_bit(ucm_dev->devnum, dev_map);
+ if (ucm_dev->devnum < IB_UCM_MAX_DEVICES)
+ clear_bit(ucm_dev->devnum, dev_map);
+ else
+ clear_bit(ucm_dev->devnum - IB_UCM_MAX_DEVICES, dev_map);
kfree(ucm_dev);
}

@@ -1237,6 +1240,28 @@ static ssize_t show_ibdev(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR(ibdev, S_IRUGO, show_ibdev, NULL);

+static dev_t oflo_maj;
+static DECLARE_BITMAP(oflo_map, IB_UCM_MAX_DEVICES);
+static int find_oflo_devnum(void)
+{
+ int ret;
+
+ if (!oflo_maj) {
+ ret = alloc_chrdev_region(&oflo_maj, 0, IB_UCM_MAX_DEVICES,
+ "infiniband_cm");
+ if (ret) {
+ printk(KERN_ERR "ucm: couldn't register dynamic device number\n");
+ return ret;
+ }
+ }
+
+ ret = find_first_zero_bit(oflo_map, IB_UCM_MAX_DEVICES);
+ if (ret >= IB_UCM_MAX_DEVICES)
+ return -1;
+
+ return ret;
+}
+
static void ib_ucm_add_one(struct ib_device *device)
{
int devnum;
@@ -1254,12 +1279,19 @@ static void ib_ucm_add_one(struct ib_device *device)
ucm_dev->ib_dev = device;

devnum = find_first_zero_bit(dev_map, IB_UCM_MAX_DEVICES);
- if (devnum >= IB_UCM_MAX_DEVICES)
- goto err;
-
- ucm_dev->devnum = devnum;
- base = devnum + IB_UCM_BASE_DEV;
- set_bit(devnum, dev_map);
+ if (devnum >= IB_UCM_MAX_DEVICES) {
+ devnum = find_oflo_devnum();
+ if (devnum < 0)
+ goto err;
+
+ ucm_dev->devnum = devnum + IB_UCM_MAX_DEVICES;
+ base = devnum + oflo_maj;
+ set_bit(devnum, oflo_map);
+ } else {
+ ucm_dev->devnum = devnum;
+ base = devnum + IB_UCM_BASE_DEV;
+ set_bit(devnum, dev_map);
+ }

cdev_init(&ucm_dev->cdev, &ucm_fops);
ucm_dev->cdev.owner = THIS_MODULE;
@@ -1285,7 +1317,10 @@ err_dev:
device_unregister(&ucm_dev->dev);
err_cdev:
cdev_del(&ucm_dev->cdev);
- clear_bit(devnum, dev_map);
+ if (ucm_dev->devnum < IB_UCM_MAX_DEVICES)
+ clear_bit(devnum, dev_map);
+ else
+ clear_bit(devnum, oflo_map);
err:
kfree(ucm_dev);
return;
@@ -1344,6 +1379,8 @@ static void __exit ib_ucm_cleanup(void)
ib_unregister_client(&ucm_client);
class_remove_file(&cm_class, &class_attr_abi_version);
unregister_chrdev_region(IB_UCM_BASE_DEV, IB_UCM_MAX_DEVICES);
+ if (oflo_maj)
+ unregister_chrdev_region(oflo_maj, IB_UCM_MAX_DEVICES);
idr_destroy(&ctx_id_table);
}


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Prev: [PATCH v2 17/18] IB/ucm: clean whitespace errors
Next: readahead: limit readahead size for small devices