Re: [PATCH 5/8] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum trailer

[Bjorn Andersson]

On Mon 20 May 06:53 PDT 2019, Alex Elder wrote:

> Replace the use of C bit-fields in the rmnet_map_dl_csum_trailer
> structure with a single integral field, using field masks to
> encode or get at sub-field values.
> 
> Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h      | 6 ++++--
>  drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 2 +-
>  2 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
> index f3231c26badd..fb1cdb4ec41f 100644
> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
> @@ -51,13 +51,15 @@ struct rmnet_map_header {
>  
>  struct rmnet_map_dl_csum_trailer {
>  	u8  reserved1;
> -	u8  valid:1;
> -	u8  reserved2:7;
> +	u8  flags;		/* RMNET_MAP_DL_* */
>  	u16 csum_start_offset;
>  	u16 csum_length;
>  	__be16 csum_value;
>  } __aligned(1);
>  
> +#define RMNET_MAP_DL_CSUM_VALID_FMASK	GENMASK(0, 0)
> +#define RMNET_MAP_DL_RESERVED_FMASK	GENMASK(7, 1)

I presume that the reserved define won't ever be referenced, but it's
good to have it "documented".

Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

Regards,
Bjorn

> +
>  struct rmnet_map_ul_csum_header {
>  	__be16 csum_start_offset;
>  	__be16 csum_info;	/* RMNET_MAP_UL_* */
> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> index 72b64114505a..a95111cdcd29 100644
> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> @@ -362,7 +362,7 @@ int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
>  
>  	csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
>  
> -	if (!csum_trailer->valid) {
> +	if (!u8_get_bits(csum_trailer->flags, RMNET_MAP_DL_CSUM_VALID_FMASK)) {
>  		priv->stats.csum_valid_unset++;
>  		return -EINVAL;
>  	}
> -- 
> 2.20.1
>