sfc: suppress duplicate nvmem partition types in efx_ef10_mtd_probe

Use a bitmap to keep track of which partition types we've already seen;
 for duplicates, return -EEXIST from efx_ef10_mtd_probe_partition() and
 thus skip adding that partition.
Duplicate partitions occur because of the A/B backup scheme used by newer
 sfc NICs.  Prior to this patch they cause sysfs_warn_dup errors because
 they have the same name, causing us not to expose any MTDs at all.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/ef10.c

@@ -6046,22 +6046,25 @@ static const struct efx_ef10_nvram_type_info efx_ef10_nvram_types[] = {
 	{ NVRAM_PARTITION_TYPE_EXPANSION_UEFI,	   0,    0, "sfc_uefi" },
 	{ NVRAM_PARTITION_TYPE_STATUS,		   0,    0, "sfc_status" }
 };
+#define EF10_NVRAM_PARTITION_COUNT	ARRAY_SIZE(efx_ef10_nvram_types)
 
 static int efx_ef10_mtd_probe_partition(struct efx_nic *efx,
 					struct efx_mcdi_mtd_partition *part,
-					unsigned int type)
+					unsigned int type,
+					unsigned long *found)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_NVRAM_METADATA_IN_LEN);
 	MCDI_DECLARE_BUF(outbuf, MC_CMD_NVRAM_METADATA_OUT_LENMAX);
 	const struct efx_ef10_nvram_type_info *info;
 	size_t size, erase_size, outlen;
+	int type_idx = 0;
 	bool protected;
 	int rc;
 
-	for (info = efx_ef10_nvram_types; ; info++) {
-		if (info ==
-		    efx_ef10_nvram_types + ARRAY_SIZE(efx_ef10_nvram_types))
+	for (type_idx = 0; ; type_idx++) {
+		if (type_idx == EF10_NVRAM_PARTITION_COUNT)
 			return -ENODEV;
+		info = efx_ef10_nvram_types + type_idx;
 		if ((type & ~info->type_mask) == info->type)
 			break;
 	}
@@ -6074,6 +6077,13 @@ static int efx_ef10_mtd_probe_partition(struct efx_nic *efx,
 	if (protected)
 		return -ENODEV; /* hide it */
 
+	/* If we've already exposed a partition of this type, hide this
+	 * duplicate.  All operations on MTDs are keyed by the type anyway,
+	 * so we can't act on the duplicate.
+	 */
+	if (__test_and_set_bit(type_idx, found))
+		return -EEXIST;
+
 	part->nvram_type = type;
 
 	MCDI_SET_DWORD(inbuf, NVRAM_METADATA_IN_TYPE, type);
@@ -6105,6 +6115,7 @@ static int efx_ef10_mtd_probe_partition(struct efx_nic *efx,
 static int efx_ef10_mtd_probe(struct efx_nic *efx)
 {
 	MCDI_DECLARE_BUF(outbuf, MC_CMD_NVRAM_PARTITIONS_OUT_LENMAX);
+	DECLARE_BITMAP(found, EF10_NVRAM_PARTITION_COUNT);
 	struct efx_mcdi_mtd_partition *parts;
 	size_t outlen, n_parts_total, i, n_parts;
 	unsigned int type;
@@ -6133,11 +6144,13 @@ static int efx_ef10_mtd_probe(struct efx_nic *efx)
 	for (i = 0; i < n_parts_total; i++) {
 		type = MCDI_ARRAY_DWORD(outbuf, NVRAM_PARTITIONS_OUT_TYPE_ID,
 					i);
-		rc = efx_ef10_mtd_probe_partition(efx, &parts[n_parts], type);
-		if (rc == 0)
-			n_parts++;
-		else if (rc != -ENODEV)
+		rc = efx_ef10_mtd_probe_partition(efx, &parts[n_parts], type,
+						  found);
+		if (rc == -EEXIST || rc == -ENODEV)
+			continue;
+		if (rc)
 			goto fail;
+		n_parts++;
 	}
 
 	rc = efx_mtd_add(efx, &parts[0].common, n_parts, sizeof(*parts));