[bug report] mtd: parsers: add support for Sercomm partitions

[Dan Carpenter]

Hello Mikhail Zhilkin,

The patch 4213e556fe2a: "mtd: parsers: add support for Sercomm
partitions" from May 3, 2022, leads to the following Smatch static
checker warning:

	drivers/mtd/parsers/scpart.c:155 scpart_parse()
	warn: missing error code here? 'mtd_get_of_node()' failed. 'res' = '0'

drivers/mtd/parsers/scpart.c
    138 static int scpart_parse(struct mtd_info *master,
    139                         const struct mtd_partition **pparts,
    140                         struct mtd_part_parser_data *data)
    141 {
    142         struct sc_part_desc *scpart_map = NULL;
    143         struct mtd_partition *parts = NULL;
    144         struct device_node *mtd_node;
    145         struct device_node *ofpart_node;
    146         struct device_node *pp;
    147         const char *partname;
    148         int nr_scparts;
    149         int nr_parts = 0;
    150         int n;
    151         int res = 0;
    152 
    153         mtd_node = mtd_get_of_node(master);
    154         if (!mtd_node)
--> 155                 goto out;
                        ^^^^^^^^

    156 
    157         ofpart_node = of_get_child_by_name(mtd_node, "partitions");
    158         if (!ofpart_node)
    159                 goto out;
                        ^^^^^^^^
Are these supposed to be success paths?

    160 
    161         nr_scparts = scpart_find_partmap(master, &scpart_map);
    162         if (nr_scparts <= 0) {

Is nr_scparts == 0 a success path?

    163                 res = nr_scparts;
    164                 goto free;
    165         }
    166 
    167         parts = kcalloc(of_get_child_count(ofpart_node), sizeof(*parts),
    168                 GFP_KERNEL);
    169         if (!parts) {
    170                 res = -ENOMEM;
    171                 goto out;
    172         }
    173 
    174         for_each_child_of_node(ofpart_node, pp) {
    175                 u32 scpart_id;
    176 
    177                 if (of_property_read_u32(pp, "sercomm,scpart-id", &scpart_id))
    178                         continue;
    179 
    180                 for (n = 0 ; n < nr_scparts ; n++)
    181                         if ((scpart_map[n].part_id != ID_ALREADY_FOUND) &&
    182                                         (scpart_id == scpart_map[n].part_id))
    183                                 break;
    184                 if (n >= nr_scparts)
    185                         /* not match */
    186                         continue;
    187 
    188                 /* add the partition found in OF into MTD partition array */
    189                 parts[nr_parts].offset = scpart_map[n].part_offs;
    190                 parts[nr_parts].size = scpart_map[n].part_bytes;
    191                 parts[nr_parts].of_node = pp;
    192 
    193                 if (!of_property_read_string(pp, "label", &partname))
    194                         parts[nr_parts].name = partname;
    195                 if (of_property_read_bool(pp, "read-only"))
    196                         parts[nr_parts].mask_flags |= MTD_WRITEABLE;
    197                 if (of_property_read_bool(pp, "lock"))
    198                         parts[nr_parts].mask_flags |= MTD_POWERUP_LOCK;
    199 
    200                 /* mark as 'done' */
    201                 scpart_map[n].part_id = ID_ALREADY_FOUND;
    202 
    203                 nr_parts++;
    204         }
    205 
    206         if (nr_parts > 0) {
    207                 *pparts = parts;
    208                 res = nr_parts;
    209         } else
    210                 pr_info("No partition in OF matches partition ID with 'SC PART MAP'.\n");
    211 
    212         of_node_put(pp);
    213 
    214 free:
    215         kfree(scpart_map);
    216         if (res <= 0)
    217                 kfree(parts);
    218 
    219 out:
    220         return res;
    221 }

regards,
dan carpenter