Re: [PATCH rdma-next V2 6/6] RDMA/core: Unify style of IOCTL commands

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Tue, Sep 06, 2016 at 05:03:14PM -0400, ira.weiny wrote:

> These defines are _not_ used anywhere in the kernel but rather define a
> device specific command _offset_ within the drm vendor ioctl range.

That is not completely true, the defines are used when setting up the
kernel ioctl #. I have no idea why they did this, to me it is
polluting a uapi header with unneeded defines which is a big no-no.

Userspace should certainly *NEVER* use these constants, removing them
is the best way to achieve that.

> When we agreed that HFI1 would use an 0x80 offset I thought that was the
> idea.[*]  That IB would have an upper range which was device specific and HFI1
> would be the first users of that range.

I'd rather not have non-unique ioctls if we can avoid it......

But even if we do, removing these indirection constants does nothing to
change that - other drivers can still alias 0x80.

That is doable, particularly if the struct is a different size, then
we still have unique ioctl numbers. With some care other vendors can
probably manage...

Jason
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