RDMA/mlx5: Fix returned type from _mlx5r_umr_zap_mkey()

As Colin reported:
 "The variable zapped_blocks is a size_t type and is being assigned a int
  return value from the call to _mlx5r_umr_zap_mkey. Since zapped_blocks is an
  unsigned type, the error check for zapped_blocks < 0 will never be true."

So separate return error and nblocks assignment.

Fixes: e73242aa14d2 ("RDMA/mlx5: Optimize DMABUF mkey page size")
Reported-by: Colin King (gmail) <colin.i.king@gmail.com>
Closes: https://lore.kernel.org/all/79166fb1-3b73-4d37-af02-a17b22eb8e64@gmail.com
Link: https://patch.msgid.link/71d8ea208ac7eaa4438af683b9afaed78625e419.1753003467.git.leon@kernel.org
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

diff --git a/drivers/infiniband/hw/mlx5/umr.c b/drivers/infiniband/hw/mlx5/umr.c
index fa5c4ea685b9d058850bbeefccf18330c224e772..054f6dae241513bf9ae0aec63faabcae20519e3e 100644 (file)
--- a/drivers/infiniband/hw/mlx5/umr.c
+++ b/drivers/infiniband/hw/mlx5/umr.c
@@ -992,6 +992,7 @@ _mlx5r_dmabuf_umr_update_pas(struct mlx5_ib_mr *mr, unsigned int flags,
 static int _mlx5r_umr_zap_mkey(struct mlx5_ib_mr *mr,
                               unsigned int flags,
                               unsigned int page_shift,
+                              size_t *nblocks,
                               bool dd)
 {
        unsigned int old_page_shift = mr->page_shift;
@@ -1000,7 +1001,6 @@ static int _mlx5r_umr_zap_mkey(struct mlx5_ib_mr *mr,
        size_t page_shift_nblocks;
        unsigned int max_log_size;
        int access_mode;
-       size_t nblocks;
        int err;
 
        access_mode = dd ? MLX5_MKC_ACCESS_MODE_KSM : MLX5_MKC_ACCESS_MODE_MTT;
@@ -1014,26 +1014,26 @@ static int _mlx5r_umr_zap_mkey(struct mlx5_ib_mr *mr,
         * Block size must be aligned to MLX5_UMR_FLEX_ALIGNMENT since it may
         * be used as offset into the XLT later on.
         */
-       nblocks = ib_umem_num_dma_blocks(mr->umem, 1UL << max_page_shift);
+       *nblocks = ib_umem_num_dma_blocks(mr->umem, 1UL << max_page_shift);
        if (dd)
-               nblocks = ALIGN(nblocks, MLX5_UMR_KSM_NUM_ENTRIES_ALIGNMENT);
+               *nblocks = ALIGN(*nblocks, MLX5_UMR_KSM_NUM_ENTRIES_ALIGNMENT);
        else
-               nblocks = ALIGN(nblocks, MLX5_UMR_MTT_NUM_ENTRIES_ALIGNMENT);
+               *nblocks = ALIGN(*nblocks, MLX5_UMR_MTT_NUM_ENTRIES_ALIGNMENT);
        page_shift_nblocks = ib_umem_num_dma_blocks(mr->umem,
                                                    1UL << page_shift);
        /* If the number of blocks at max possible page shift is greater than
         * the number of blocks at the new page size, we should just go over the
         * whole mkey entries.
         */
-       if (nblocks >= page_shift_nblocks)
-               nblocks = 0;
+       if (*nblocks >= page_shift_nblocks)
+               *nblocks = 0;
 
        /* Make the first nblocks entries non-present without changing
         * page size yet.
         */
-       if (nblocks)
+       if (*nblocks)
                mr->page_shift = max_page_shift;
-       err = _mlx5r_dmabuf_umr_update_pas(mr, flags, 0, nblocks, dd);
+       err = _mlx5r_dmabuf_umr_update_pas(mr, flags, 0, *nblocks, dd);
        if (err) {
                mr->page_shift = old_page_shift;
                return err;
@@ -1042,7 +1042,7 @@ static int _mlx5r_umr_zap_mkey(struct mlx5_ib_mr *mr,
        /* Change page size to the max page size now that the MR is completely
         * non-present.
         */
-       if (nblocks) {
+       if (*nblocks) {
                err = mlx5r_umr_update_mr_page_shift(mr, max_page_shift, dd);
                if (err) {
                        mr->page_shift = old_page_shift;
@@ -1050,7 +1050,7 @@ static int _mlx5r_umr_zap_mkey(struct mlx5_ib_mr *mr,
                }
        }
 
-       return nblocks;
+       return 0;
 }
 
 /**
@@ -1085,10 +1085,10 @@ int mlx5r_umr_dmabuf_update_pgsz(struct mlx5_ib_mr *mr, u32 xlt_flags,
        size_t total_blocks;
        int err;
 
-       zapped_blocks = _mlx5r_umr_zap_mkey(mr, xlt_flags, page_shift,
-                                           mr->data_direct);
-       if (zapped_blocks < 0)
-               return zapped_blocks;
+       err = _mlx5r_umr_zap_mkey(mr, xlt_flags, page_shift, &zapped_blocks,
+                                 mr->data_direct);
+       if (err)
+               return err;
 
        /* _mlx5r_umr_zap_mkey already enables the mkey */
        xlt_flags &= ~MLX5_IB_UPD_XLT_ENABLE;