Re: linux-next: build failure after merge of the xarray tree

Matthew Wilcox
2019-02-12T16:15:28Z

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);