Re: [PATCH v5 for-next 7/7] RDMA/bnxt_re: Enable low latency push

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Jun 12, 2023 at 02:49:02AM -0700, Selvin Xavier wrote:

> +static int UVERBS_HANDLER(BNXT_RE_METHOD_ALLOC_PAGE)(struct uverbs_attr_bundle *attrs)
> +{
> +	struct ib_uobject *uobj = uverbs_attr_get_uobject(attrs, BNXT_RE_ALLOC_PAGE_HANDLE);
> +	enum bnxt_re_alloc_page_type alloc_type;
> +	struct bnxt_re_user_mmap_entry *entry;
> +	enum bnxt_re_mmap_flag mmap_flag;
> +	struct bnxt_qplib_chip_ctx *cctx;
> +	struct bnxt_re_ucontext *uctx;
> +	struct bnxt_re_dev *rdev;
> +	u64 mmap_offset;
> +	u32 length;
> +	u32 dpi;
> +	u64 dbr;
> +	int err;
> +
> +	uctx = container_of(ib_uverbs_get_ucontext(attrs), struct bnxt_re_ucontext, ib_uctx);
> +	if (IS_ERR(uctx))
> +		return PTR_ERR(uctx);
> +
> +	err = uverbs_get_const(&alloc_type, attrs, BNXT_RE_ALLOC_PAGE_TYPE);
> +	if (err)
> +		return err;
> +
> +	rdev = uctx->rdev;
> +	cctx = rdev->chip_ctx;
> +
> +	switch (alloc_type) {
> +	case BNXT_RE_ALLOC_WC_PAGE:
> +		if (cctx->modes.db_push)  {
> +			if (bnxt_qplib_alloc_dpi(&rdev->qplib_res, &uctx->wcdpi,
> +						 uctx, BNXT_QPLIB_DPI_TYPE_WC))
> +				return -ENOMEM;
> +			length = PAGE_SIZE;
> +			dpi = uctx->wcdpi.dpi;
> +			dbr = (u64)uctx->wcdpi.umdbr;
> +			mmap_flag = BNXT_RE_MMAP_WC_DB;
> +		} else {
> +			return -EINVAL;
> +		}
> +
> +		break;
> +
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	entry = bnxt_re_mmap_entry_insert(uctx, dbr, mmap_flag, &mmap_offset);
> +	if (IS_ERR(entry))
> +		return PTR_ERR(entry);
> +
> +	uobj->object = entry;
> +	uverbs_finalize_uobj_create(attrs, BNXT_RE_ALLOC_PAGE_HANDLE);

uverbs_finalize_uobj_create() is supposed to be called once the
function cannot fail anymore

> +	err = uverbs_copy_to(attrs, BNXT_RE_ALLOC_PAGE_MMAP_OFFSET,
> +			     &mmap_offset, sizeof(mmap_offset));
> +	if (err)
> +		return err;

Because there is no way to undo it on error.

So the error handling here needs adjusting

Jason