On Tue, Feb 12, 2019 at 04:20:03PM +1100, Stephen Rothwell wrote:
> Caused by commit
> 
>   a3e4d3f97ec8 ("XArray: Redesign xa_alloc API")
> 
> interacting with commits
> 
>   e59178d895af ("RDMA/devices: Use xarray to store the clients")
>   0df91bb67334 ("RDMA/devices: Use xarray to store the client_data")
> 
> from the rdma tree.
> 
> Its a bit of a pain modifying a published API like this :-(

Yes, it is.  I wasn't expecting people to actually start using it ;-)

Seriously, there are several defects in the published API which do
warrant a change.  The most severe one is that it's really easy to
forget to initialise the start index.  And while I'm making that change,
I should fix smaller things like the errno at the same time.

> I have added the following merge fixup patch for today (I assume some
> of the assignments are also now redundant).

I think the first of these should be using the alloc_cyclic API, like this:

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 283ecc2aee89..d0b56c70a553 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -586,20 +586,8 @@ static int assign_name(struct ib_device *device, const 
char *name)
        }
        strlcpy(device->name, dev_name(&device->dev), IB_DEVICE_NAME_MAX);
 
-       /* Cyclically allocate a user visible ID for the device */
-       device->index = last_id;
-       ret = xa_alloc(&devices, &device->index, device,
-                      XA_LIMIT(last_id, INT_MAX), GFP_KERNEL);
-       if (ret == -ENOSPC) {
-               device->index = 0;
-               ret = xa_alloc(&devices, &device->index, device,
-                              XA_LIMIT(0, INT_MAX), GFP_KERNEL);
-       }
-       if (ret)
-               goto out;
-       last_id = device->index + 1;
-
-       ret = 0;
+       ret = xa_alloc_cyclic(&devices, &device->index, device, xa_limit_31b,
+                       &last_id, GFP_KERNEL);
 
 out:
        up_write(&devices_rwsem);
@@ -750,7 +738,7 @@ int ib_register_device(struct ib_device *device, const char 
*name)
        int ret;
 
        ret = assign_name(device, name);
-       if (ret)
+       if (ret < 0)
                return ret;
 
        ret = setup_device(device);


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