Re: [PATCH] IB/core: Fix two kernel warnings triggered by rxe registration

[Bart Van Assche <Bart.VanAssche@wdc.com>]

On Wed, 2017-12-27 at 15:56 -0700, Jason Gunthorpe wrote:
> I'm a little more worried about the ib_device_register_sysfs - why was
> the WARN_ON ever there?

That WARN_ON() statement was introduced by commit 97a9ea848016 ("IB/core:
Initialize ib_device.dev.parent earlier"):

[ ... ]
diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index c1fb545e8d78..daadf3130c9f 100644
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -1258,7 +1258,7 @@ int ib_device_register_sysfs(struct ib_device *device,
        int ret;
        int i;
  
-       device->dev.parent = device->dma_device;
+       WARN_ON_ONCE(!device->dev.parent);
        ret = dev_set_name(class_dev, "%s", device->name);
        if (ret)
                return ret;
[ ... ]

Since ib_device_register_sysfs() does not use the parent pointer in any way
I think it is sufficient to check the parent pointer in ib_register_device()
and to leave out any parent pointer checks from ib_device_register_sysfs().

> What do you think about this as a clarification Bart?
> [ ... ]

OK, I will add a parent pointer check in the code paths that dereference that
pointer.

Bart.