Re: [PATCH v2 22/22] ata: ahci_xgene: Fix id array access in xgene_ahci_read_id()

[Hannes Reinecke <hare@suse.de>]

On 1/4/22 11:58 AM, Damien Le Moal wrote:
> ATA IDENTIFY command returns an array of le16 words. Accessing it as a
> u16 array triggers the following sparse warning:
> 
> drivers/ata/ahci_xgene.c:262:33: warning: invalid assignment: &=
> drivers/ata/ahci_xgene.c:262:33:    left side has type unsigned short
> drivers/ata/ahci_xgene.c:262:33:    right side has type restricted __le16
> 
> Use a local variable to explicitly cast the id array to __le16 to avoid
> this warning.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> ---
>  drivers/ata/ahci_xgene.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
> index 68ec7e9430b2..d5075d0f8cb1 100644
> --- a/drivers/ata/ahci_xgene.c
> +++ b/drivers/ata/ahci_xgene.c
> @@ -239,6 +239,7 @@ static bool xgene_ahci_is_memram_inited(struct xgene_ahci_context *ctx)
>  static unsigned int xgene_ahci_read_id(struct ata_device *dev,
>  				       struct ata_taskfile *tf, u16 *id)
>  {
> +	__le16 *__id = (__le16 *)id;
>  	u32 err_mask;
>  
>  	err_mask = ata_do_dev_read_id(dev, tf, id);
> @@ -259,7 +260,7 @@ static unsigned int xgene_ahci_read_id(struct ata_device *dev,
>  	 *
>  	 * Clear reserved bit 8 (DEVSLP bit) as we don't support DEVSLP
>  	 */
> -	id[ATA_ID_FEATURE_SUPP] &= cpu_to_le16(~(1 << 8));
> +	__id[ATA_ID_FEATURE_SUPP] &= cpu_to_le16(~(1 << 8));
>  
>  	return 0;
>  }
> 
Hmm. I would think that the 'id' argument is wrong; it really should be
'__le16 *', as it only gets converted later on with the call to
swap_buf_le16(id, ATA_ID_WORDS) in
drivers/ata/libata-core.c:ata_dev_read_id(). So when this function is
called the argument really _is_ __le16, only the declaration doesn't
tell us.

Maybe one should rather fix this?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer