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Message-ID: <ad9a6bf4-a850-69d2-ec20-cbafcfa5b22b@linaro.org>
Date: Tue, 9 Mar 2021 18:13:16 -0600
From: Alex Elder <elder@...aro.org>
To: subashab@...eaurora.org, stranche@...eaurora.org,
davem@...emloft.net, kuba@...nel.org
Cc: sharathv@...eaurora.org, bjorn.andersson@...aro.org,
evgreen@...omium.org, cpratapa@...eaurora.org,
David.Laight@...LAB.COM, elder@...nel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 5/6] net: qualcomm: rmnet: don't use C
bit-fields in rmnet checksum trailer
On 3/9/21 6:48 AM, Alex Elder wrote:
> Replace the use of C bit-fields in the rmnet_map_dl_csum_trailer
> structure with a single one-byte field, using constant field masks
> to encode or get at embedded values.
>
> Signed-off-by: Alex Elder <elder@...aro.org>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> v3: Use BIT(x) and don't use u8_get_bits() for the checksum valid flag
>
> .../ethernet/qualcomm/rmnet/rmnet_map_data.c | 2 +-
> include/linux/if_rmnet.h | 17 +++++++----------
> 2 files changed, 8 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> index 3291f252d81b0..72dbbe2c27bd7 100644
> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> @@ -365,7 +365,7 @@ 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 (csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG) {
This was the actual problem. The result of the new
test is the reverse of what it should be.
In any case, I'm taking a break from this for a while.
-Alex
> priv->stats.csum_valid_unset++;
> return -EINVAL;
> }
> diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
> index 22ccc89bb5d8e..a848bb2e0dad0 100644
> --- a/include/linux/if_rmnet.h
> +++ b/include/linux/if_rmnet.h
> @@ -19,21 +19,18 @@ struct rmnet_map_header {
> #define MAP_PAD_LEN_FMASK GENMASK(5, 0)
>
> struct rmnet_map_dl_csum_trailer {
> - u8 reserved1;
> -#if defined(__LITTLE_ENDIAN_BITFIELD)
> - u8 valid:1;
> - u8 reserved2:7;
> -#elif defined (__BIG_ENDIAN_BITFIELD)
> - u8 reserved2:7;
> - u8 valid:1;
> -#else
> -#error "Please fix <asm/byteorder.h>"
> -#endif
> + u8 reserved1;
> + u8 flags; /* MAP_CSUM_DL_*_FMASK */
> __be16 csum_start_offset;
> __be16 csum_length;
> __be16 csum_value;
> } __aligned(1);
>
> +/* rmnet_map_dl_csum_trailer flags field:
> + * VALID: 1 = checksum and length valid; 0 = ignore them
> + */
> +#define MAP_CSUM_DL_VALID_FLAG BIT(0)
> +
> struct rmnet_map_ul_csum_header {
> __be16 csum_start_offset;
> #if defined(__LITTLE_ENDIAN_BITFIELD)
>
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