Re: [PATCH for-next] RDMA/core: Add writev to uverbs file descriptor

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Mar 11, 2026 at 01:33:37PM -0400, Dennis Dalessandro wrote:
> From: Dean Luick <dean.luick@cornelisnetworks.com>
> 
> Add a writev pass-through between the uverbs file descriptor and
> infiniband devices.  Interested devices may subscribe to this
> functionality.
> 
> The goal is to keep all the semantics of the user interface the same so
> it's an easy migration to the uverbs cdev from the private cdev. The idea
> is that all the command and control is still ioctl, but the "data path" is
> still using the writev() to pass in the iovecs.

So the main issue was the cdev, not necessary that there was another
file descriptor.

Another options you could have a ioctl to create a compatability
anonymous fd that just does this writev flow. IIRC this was a
performance path in hfi1 so it would be better to remove some layers
of indirection.

The slower control path can run on the normal ioctl mechanism and just
run your write over this addition FD

I'm not adverse to this patch, but something to thinkg about.

Jason