Re: [PATCH AUTOSEL 3.18 12/16] sfc: suppress duplicate nvmem partition types in efx_ef10_mtd_probe

[Bert Kenward <bkenward@solarflare.com>]

On 15/02/2019 02:15, Sasha Levin wrote:
> From: Edward Cree <ecree@solarflare.com>
> 
> [ Upstream commit 3366463513f544c12c6b88c13da4462ee9e7a1a1 ]
> 
> 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>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

I don't think this particularly needs to go to stable, but if it does it
should be accompanied by:
  c65285428b6e ("sfc: initialise found bitmap in efx_ef10_mtd_probe")

Bert.

> ---
>  drivers/net/ethernet/sfc/ef10.c | 29 +++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
> index 010009d64017..84a17b41313c 100644
> --- a/drivers/net/ethernet/sfc/ef10.c
> +++ b/drivers/net/ethernet/sfc/ef10.c
> @@ -3407,22 +3407,25 @@ static const struct efx_ef10_nvram_type_info efx_ef10_nvram_types[] = {
>  	{ NVRAM_PARTITION_TYPE_LICENSE,		   0,    0, "sfc_license" },
>  	{ NVRAM_PARTITION_TYPE_PHY_MIN,		   0xff, 0, "sfc_phy_fw" },
>  };
> +#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;
>  	}
> @@ -3435,6 +3438,13 @@ 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);
> @@ -3463,6 +3473,7 @@ 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;
> @@ -3491,11 +3502,13 @@ 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));
>