Re: [PATCH rdma-next v4 4/4] RDMA/umem: Move to allocate SG table from pages

On Tue, Sep 29, 2020 at 04:59:29PM -0300, Jason Gunthorpe wrote:

On Sun, Sep 27, 2020 at 09:46:47AM +0300, Leon Romanovsky wrote:

...

@@ -296,11 +223,17 @@ static struct ib_umem *__ib_umem_get(struct ib_device *device, goto umem_release;

cur_base += ret * PAGE_SIZE;

• npages   -= ret;
  

• sg = ib_umem_add_sg_table(sg, page_list, ret,
  

• 	dma_get_max_seg_size(device->dma_device),
  

• 	&umem->sg_nents);
  

• npages -= ret;
  

• sg = __sg_alloc_table_from_pages(
  

• 	&umem->sg_head, page_list, ret, 0, ret << PAGE_SHIFT,
  

• 	dma_get_max_seg_size(device->dma_device), sg, npages,
  

• 	GFP_KERNEL);
  

• umem->sg_nents = umem->sg_head.nents;
  

• if (IS_ERR(sg)) {
  

• 	unpin_user_pages_dirty_lock(page_list, ret, 0);
  

• 	ret = PTR_ERR(sg);
  

• 	goto umem_release;
  

• }
  

  }

  sg_mark_end(sg);

Does it still need the sg_mark_end?

It is preserved here for correctness, the release logic doesn't rely on this marker, but it is better to leave it.

Thanks

Jason