Re: [PATCH rdma-next v4 06/16] RDMA/uverbs: Push out CQ buffer umem processing into a helper

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, May 12, 2026 at 08:40:26PM +0200, Jiri Pirko wrote:
> Tue, May 12, 2026 at 08:03:42PM CEST, jgg@ziepe.ca wrote:
> >On Thu, May 07, 2026 at 02:52:21PM +0200, Jiri Pirko wrote:
> >
> >> +static int uverbs_create_cq_get_buffer_desc(struct uverbs_attr_bundle *attrs,
> >> +					    struct ib_uverbs_buffer_desc *desc)
> >> +{
> >> +	struct ib_device *ib_dev = attrs->context->device;
> >> +	int ret;
> >> +
> >> +	if (uverbs_attr_is_valid(attrs,
> >> UVERBS_ATTR_CREATE_CQ_BUFFER_VA)) {
> >
> >I know this is just moving code, but I've always disliked this
> >function. I learned a trick using a case statement for this recently:
> >
> >	u32 present_attrs = 0;
> >	if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_VA))
> >		present_attrs |= BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_VA);
> >	if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH))
> >		present_attrs |= BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH);
> >	if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_FD))
> >		present_attrs |= BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_FD);
> >	if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET))
> >		present_attrs |= BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET);
> >
> >	switch (present_attrs) {
> >	case 0:
> >		return -ENODATA;
> >	case BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_VA) |
> >		BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH):
> >[..]
> >		return 0;
> >	case BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_FD) |
> >		BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET) |
> >		BIT(UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH):
> >[..]
> >		return 0;
> >	default:
> >		return -EINVAL;
> >	}
> >
> >No need to build the complex tests to check in each branch if the
> >other branch attributes are presented.
> 
> As this patch is just moving existing code, could we do this in a
> follow-up? Patchset is already long enough. Will add that to my todo
> list if you are okay with it.

sure, I was just annoyed trying to understand this code again

Jason