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    Subject[PATCH v2 12/18] IB/umad: increase maximum devices supported
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    Date
    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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