[kbuild] drivers/vdpa/mlx5/core/mr.c:282 map_direct_mr() warn: missing error code 'err'

From: Dan Carpenter
Date: Fri Apr 09 2021 - 04:52:59 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: e49d033bddf5b565044e2abe4241353959bc9120
commit: 94abbccdf2916cb03f9626f2d36c6e9971490c12 vdpa/mlx5: Add shared memory registration code
config: microblaze-randconfig-m031-20210405 (attached as .config)
compiler: microblaze-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

New smatch warnings:
drivers/vdpa/mlx5/core/mr.c:282 map_direct_mr() warn: missing error code 'err'

Old smatch warnings:
drivers/vdpa/mlx5/core/mr.c:350 add_direct_chain() error: uninitialized symbol 'err'.
drivers/vdpa/mlx5/core/mr.c:483 mlx5_vdpa_handle_set_map() error: uninitialized symbol 'err'.

vim +/err +282 drivers/vdpa/mlx5/core/mr.c

94abbccdf2916c Eli Cohen 2020-08-04 226 static int map_direct_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_direct_mr *mr,
94abbccdf2916c Eli Cohen 2020-08-04 227 struct vhost_iotlb *iotlb)
94abbccdf2916c Eli Cohen 2020-08-04 228 {
94abbccdf2916c Eli Cohen 2020-08-04 229 struct vhost_iotlb_map *map;
94abbccdf2916c Eli Cohen 2020-08-04 230 unsigned long lgcd = 0;
94abbccdf2916c Eli Cohen 2020-08-04 231 int log_entity_size;
94abbccdf2916c Eli Cohen 2020-08-04 232 unsigned long size;
94abbccdf2916c Eli Cohen 2020-08-04 233 u64 start = 0;
94abbccdf2916c Eli Cohen 2020-08-04 234 int err;
94abbccdf2916c Eli Cohen 2020-08-04 235 struct page *pg;
94abbccdf2916c Eli Cohen 2020-08-04 236 unsigned int nsg;
94abbccdf2916c Eli Cohen 2020-08-04 237 int sglen;
94abbccdf2916c Eli Cohen 2020-08-04 238 u64 pa;
94abbccdf2916c Eli Cohen 2020-08-04 239 u64 paend;
94abbccdf2916c Eli Cohen 2020-08-04 240 struct scatterlist *sg;
94abbccdf2916c Eli Cohen 2020-08-04 241 struct device *dma = mvdev->mdev->device;
94abbccdf2916c Eli Cohen 2020-08-04 242 int ret;
94abbccdf2916c Eli Cohen 2020-08-04 243
94abbccdf2916c Eli Cohen 2020-08-04 244 for (map = vhost_iotlb_itree_first(iotlb, mr->start, mr->end - 1);
94abbccdf2916c Eli Cohen 2020-08-04 245 map; map = vhost_iotlb_itree_next(map, start, mr->end - 1)) {
94abbccdf2916c Eli Cohen 2020-08-04 246 size = maplen(map, mr);
94abbccdf2916c Eli Cohen 2020-08-04 247 lgcd = gcd(lgcd, size);
94abbccdf2916c Eli Cohen 2020-08-04 248 start += size;
94abbccdf2916c Eli Cohen 2020-08-04 249 }
94abbccdf2916c Eli Cohen 2020-08-04 250 log_entity_size = ilog2(lgcd);
94abbccdf2916c Eli Cohen 2020-08-04 251
94abbccdf2916c Eli Cohen 2020-08-04 252 sglen = 1 << log_entity_size;
94abbccdf2916c Eli Cohen 2020-08-04 253 nsg = MLX5_DIV_ROUND_UP_POW2(mr->end - mr->start, log_entity_size);
94abbccdf2916c Eli Cohen 2020-08-04 254
94abbccdf2916c Eli Cohen 2020-08-04 255 err = sg_alloc_table(&mr->sg_head, nsg, GFP_KERNEL);
94abbccdf2916c Eli Cohen 2020-08-04 256 if (err)
94abbccdf2916c Eli Cohen 2020-08-04 257 return err;
94abbccdf2916c Eli Cohen 2020-08-04 258
94abbccdf2916c Eli Cohen 2020-08-04 259 sg = mr->sg_head.sgl;
94abbccdf2916c Eli Cohen 2020-08-04 260 for (map = vhost_iotlb_itree_first(iotlb, mr->start, mr->end - 1);
94abbccdf2916c Eli Cohen 2020-08-04 261 map; map = vhost_iotlb_itree_next(map, mr->start, mr->end - 1)) {
94abbccdf2916c Eli Cohen 2020-08-04 262 paend = map->addr + maplen(map, mr);
94abbccdf2916c Eli Cohen 2020-08-04 263 for (pa = map->addr; pa < paend; pa += sglen) {
94abbccdf2916c Eli Cohen 2020-08-04 264 pg = pfn_to_page(__phys_to_pfn(pa));
94abbccdf2916c Eli Cohen 2020-08-04 265 if (!sg) {
94abbccdf2916c Eli Cohen 2020-08-04 266 mlx5_vdpa_warn(mvdev, "sg null. start 0x%llx, end 0x%llx\n",
94abbccdf2916c Eli Cohen 2020-08-04 267 map->start, map->last + 1);
94abbccdf2916c Eli Cohen 2020-08-04 268 err = -ENOMEM;
94abbccdf2916c Eli Cohen 2020-08-04 269 goto err_map;
94abbccdf2916c Eli Cohen 2020-08-04 270 }
94abbccdf2916c Eli Cohen 2020-08-04 271 sg_set_page(sg, pg, sglen, 0);
94abbccdf2916c Eli Cohen 2020-08-04 272 sg = sg_next(sg);
94abbccdf2916c Eli Cohen 2020-08-04 273 if (!sg)
94abbccdf2916c Eli Cohen 2020-08-04 274 goto done;
94abbccdf2916c Eli Cohen 2020-08-04 275 }
94abbccdf2916c Eli Cohen 2020-08-04 276 }
94abbccdf2916c Eli Cohen 2020-08-04 277 done:
94abbccdf2916c Eli Cohen 2020-08-04 278 mr->log_size = log_entity_size;
94abbccdf2916c Eli Cohen 2020-08-04 279 mr->nsg = nsg;
94abbccdf2916c Eli Cohen 2020-08-04 280 ret = dma_map_sg_attrs(dma, mr->sg_head.sgl, mr->nsg, DMA_BIDIRECTIONAL, 0);
94abbccdf2916c Eli Cohen 2020-08-04 281 if (!ret)
94abbccdf2916c Eli Cohen 2020-08-04 @282 goto err_map;
^^^^^^^^^^^^^
This feels deliberate but it's an error path so that's sort of
confusing... Not sure.

94abbccdf2916c Eli Cohen 2020-08-04 283
94abbccdf2916c Eli Cohen 2020-08-04 284 err = create_direct_mr(mvdev, mr);
94abbccdf2916c Eli Cohen 2020-08-04 285 if (err)
94abbccdf2916c Eli Cohen 2020-08-04 286 goto err_direct;
94abbccdf2916c Eli Cohen 2020-08-04 287
94abbccdf2916c Eli Cohen 2020-08-04 288 return 0;
94abbccdf2916c Eli Cohen 2020-08-04 289
94abbccdf2916c Eli Cohen 2020-08-04 290 err_direct:
94abbccdf2916c Eli Cohen 2020-08-04 291 dma_unmap_sg_attrs(dma, mr->sg_head.sgl, mr->nsg, DMA_BIDIRECTIONAL, 0);
94abbccdf2916c Eli Cohen 2020-08-04 292 err_map:
94abbccdf2916c Eli Cohen 2020-08-04 293 sg_free_table(&mr->sg_head);
94abbccdf2916c Eli Cohen 2020-08-04 294 return err;
94abbccdf2916c Eli Cohen 2020-08-04 295 }

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