Re: [kbuild] [leon-rdma:rdma-next 67/71] drivers/infiniband/hw/mlx5/qp.c:861:42: sparse: sparse: subtraction of Share your drugs

[Jason Gunthorpe <jgg@nvidia.com>]

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On Tue, Sep 29, 2020 at 10:24:41PM +0300, Dan Carpenter wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git  rdma-next
> head:   41142fada89c77281000029c8f4ce28ea8ed95ac
> commit: b287f59569b5ddead80547afb3fbe54ba19d71a2 [67/71] RDMA/mlx5: Use mlx5_umem_find_best_quantized_pgoff() for WQ
> config: i386-randconfig-s002-20200929 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
> reproduce:
>         # apt-get install sparse
>         # sparse version: v0.6.2-201-g24bdaac6-dirty
>         # https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/commit/?id=b287f59569b5ddead80547afb3fbe54ba19d71a2 
>         git remote add leon-rdma https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git 
>         git fetch --no-tags leon-rdma rdma-next
>         git checkout b287f59569b5ddead80547afb3fbe54ba19d71a2
>         # save the attached .config to linux build tree
>         make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> 	echo
> 	echo "sparse warnings: (new ones prefixed by >>)"
> 	echo
> >> drivers/infiniband/hw/mlx5/qp.c:861:42: sparse: sparse: subtraction of functions? Share your drugs
> 
> vim +861 drivers/infiniband/hw/mlx5/qp.c
> 
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  830  static int create_user_rq(struct mlx5_ib_dev *dev, struct ib_pd *pd,
> b0ea0fa5435f9d Jason Gunthorpe    2019-01-09  831  			  struct ib_udata *udata, struct mlx5_ib_rwq *rwq,
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  832  			  struct mlx5_ib_create_wq *ucmd)
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  833  {
> 89944450547334 Shamir Rabinovitch 2019-02-07  834  	struct mlx5_ib_ucontext *ucontext = rdma_udata_to_drv_context(
> 89944450547334 Shamir Rabinovitch 2019-02-07  835  		udata, struct mlx5_ib_ucontext, ibucontext);
> b287f59569b5dd Jason Gunthorpe    2020-08-21  836  	unsigned long page_size = 0;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  837  	u32 offset = 0;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  838  	int err;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  839  
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  840  	if (!ucmd->buf_addr)
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  841  		return -EINVAL;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  842  
> c320e527e15483 Moni Shoua         2020-01-15  843  	rwq->umem = ib_umem_get(&dev->ib_dev, ucmd->buf_addr, rwq->buf_size, 0);
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  844  	if (IS_ERR(rwq->umem)) {
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  845  		mlx5_ib_dbg(dev, "umem_get failed\n");
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  846  		err = PTR_ERR(rwq->umem);
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  847  		return err;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  848  	}
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  849  
> b287f59569b5dd Jason Gunthorpe    2020-08-21  850  	page_size = mlx5_umem_find_best_quantized_pgoff(
> b287f59569b5dd Jason Gunthorpe    2020-08-21  851  		rwq->umem, wq, log_wq_pg_sz, MLX5_ADAPTER_PAGE_SHIFT,
> b287f59569b5dd Jason Gunthorpe    2020-08-21  852  		page_offset, 64, &rwq->rq_page_offset);
> b287f59569b5dd Jason Gunthorpe    2020-08-21  853  	if (!page_size) {
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  854  		mlx5_ib_warn(dev, "bad offset\n");
> b287f59569b5dd Jason Gunthorpe    2020-08-21  855  		err = -EINVAL;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  856  		goto err_umem;
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  857  	}
> 79b20a6c3014c7 Yishai Hadas       2016-05-23  858  
> b287f59569b5dd Jason Gunthorpe    2020-08-21  859  	rwq->rq_num_pas = ib_umem_num_dma_blocks(rwq->umem, page_size);
> b287f59569b5dd Jason Gunthorpe    2020-08-21  860  	rwq->page_shift = order_base_2(page_size);
> b287f59569b5dd Jason Gunthorpe    2020-08-21 @861  	rwq->log_page_size =  page_shift - page_shift;
>                                                                               ^^^^^^^^^^^^^^^^^^^^^^^^
> Sharing is caring.  #Drugs #NancyReagan

Oh neat

Should be
	rwq->log_page_size =  rwq->page_shift - MLX5_ADAPTER_PAGE_SHIFT;

Thanks,
Jason