Re: [PATCH 2/7] RDMA/hfi1: don't pass bogus GFP_ flags to dma_alloc_coherent

Dean Luick
2022-11-16T14:41:11Z

On 11/13/2022 10:35 AM, Christoph Hellwig wrote:
> dma_alloc_coherent is an opaque allocator that only uses the GFP_ flags
> for allocation context control. Don't pass GFP_USER which doesn't make
> sense for a kernel DMA allocation or __GFP_COMP which makes no sense
> for an allocation that can't in any way be converted to a page pointer.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/infiniband/hw/hfi1/init.c | 21 +++------------------
> 1 file changed, 3 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/infiniband/hw/hfi1/init.c b/drivers/infiniband/hw/hfi1/init.c
> index 436372b314312..24c0f0d257fc9 100644
> --- a/drivers/infiniband/hw/hfi1/init.c
> +++ b/drivers/infiniband/hw/hfi1/init.c
> @@ -1761,17 +1761,11 @@ int hfi1_create_rcvhdrq(struct hfi1_devdata *dd, struct hfi1_ctxtdata *rcd)
> unsigned amt;
>
> if (!rcd->rcvhdrq) {
> - gfp_t gfp_flags;
> -
> amt = rcvhdrq_size(rcd);
>
> - if (rcd->ctxt < dd->first_dyn_alloc_ctxt || rcd->is_vnic)
> - gfp_flags = GFP_KERNEL;
> - else
> - gfp_flags = GFP_USER;
> rcd->rcvhdrq = dma_alloc_coherent(&dd->pcidev->dev, amt,
> &rcd->rcvhdrq_dma,
> - gfp_flags | __GFP_COMP);
> + GFP_KERNEL);

A user context receive header queue may be mapped into user space. Is that not the use case for GFP_USER? The above conditional is what decides.

Why do you think GFP_USER should be removed here?

-Dean
External recipient