From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Alex Elder <elder@linaro.org>
Cc: subashab@codeaurora.org, stranche@codeaurora.org,
davem@davemloft.net, kuba@kernel.org, sharathv@codeaurora.org,
evgreen@chromium.org, cpratapa@codeaurora.org, elder@kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 6/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum header
Date: Thu, 4 Mar 2021 23:26:24 -0600 [thread overview]
Message-ID: <YEHBANdYaI+Meb7t@builder.lan> (raw)
In-Reply-To: <20210304223431.15045-7-elder@linaro.org>
On Thu 04 Mar 16:34 CST 2021, Alex Elder wrote:
> Replace the use of C bit-fields in the rmnet_map_ul_csum_header
> structure with a single two-byte (big endian) structure member,
> and use field masks to encode or get values within it.
>
> Previously rmnet_map_ipv4_ul_csum_header() would update values in
> the host byte-order fields, and then forcibly fix their byte order
> using a combination of byte order operations and types.
>
> Instead, just compute the value that needs to go into the new
> structure member and save it with a simple byte-order conversion.
>
> Make similar simplifications in rmnet_map_ipv6_ul_csum_header().
>
> Finally, in rmnet_map_checksum_uplink_packet() a set of assignments
> zeroes every field in the upload checksum header. Replace that with
> a single memset() operation.
>
> Signed-off-by: Alex Elder <elder@linaro.org>
> ---
> .../ethernet/qualcomm/rmnet/rmnet_map_data.c | 34 ++++++-------------
> include/linux/if_rmnet.h | 21 ++++++------
> 2 files changed, 21 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> index 29d485b868a65..db76bbf000aa1 100644
> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> @@ -198,23 +198,19 @@ rmnet_map_ipv4_ul_csum_header(void *iphdr,
> struct rmnet_map_ul_csum_header *ul_header,
> struct sk_buff *skb)
> {
> - __be16 *hdr = (__be16 *)ul_header;
> struct iphdr *ip4h = iphdr;
> u16 offset;
> + u16 val;
>
> offset = skb_transport_header(skb) - (unsigned char *)iphdr;
> ul_header->csum_start_offset = htons(offset);
>
> - ul_header->csum_insert_offset = skb->csum_offset;
> - ul_header->csum_enabled = 1;
> + val = be16_encode_bits(1, MAP_CSUM_UL_ENABLED_FMASK);
Why are you using be16_ here? Won't that cancel the htons() below?
Regards,
Bjorn
> if (ip4h->protocol == IPPROTO_UDP)
> - ul_header->udp_ind = 1;
> - else
> - ul_header->udp_ind = 0;
> + val |= be16_encode_bits(1, MAP_CSUM_UL_UDP_FMASK);
> + val |= be16_encode_bits(skb->csum_offset, MAP_CSUM_UL_OFFSET_FMASK);
>
> - /* Changing remaining fields to network order */
> - hdr++;
> - *hdr = htons((__force u16)*hdr);
> + ul_header->csum_info = htons(val);
>
> skb->ip_summed = CHECKSUM_NONE;
>
> @@ -241,24 +237,19 @@ rmnet_map_ipv6_ul_csum_header(void *ip6hdr,
> struct rmnet_map_ul_csum_header *ul_header,
> struct sk_buff *skb)
> {
> - __be16 *hdr = (__be16 *)ul_header;
> struct ipv6hdr *ip6h = ip6hdr;
> u16 offset;
> + u16 val;
>
> offset = skb_transport_header(skb) - (unsigned char *)ip6hdr;
> ul_header->csum_start_offset = htons(offset);
>
> - ul_header->csum_insert_offset = skb->csum_offset;
> - ul_header->csum_enabled = 1;
> -
> + val = be16_encode_bits(1, MAP_CSUM_UL_ENABLED_FMASK);
> if (ip6h->nexthdr == IPPROTO_UDP)
> - ul_header->udp_ind = 1;
> - else
> - ul_header->udp_ind = 0;
> + val |= be16_encode_bits(1, MAP_CSUM_UL_UDP_FMASK);
> + val |= be16_encode_bits(skb->csum_offset, MAP_CSUM_UL_OFFSET_FMASK);
>
> - /* Changing remaining fields to network order */
> - hdr++;
> - *hdr = htons((__force u16)*hdr);
> + ul_header->csum_info = htons(val);
>
> skb->ip_summed = CHECKSUM_NONE;
>
> @@ -425,10 +416,7 @@ void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
> }
>
> sw_csum:
> - ul_header->csum_start_offset = 0;
> - ul_header->csum_insert_offset = 0;
> - ul_header->csum_enabled = 0;
> - ul_header->udp_ind = 0;
> + memset(ul_header, 0, sizeof(*ul_header));
>
> priv->stats.csum_sw++;
> }
> diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
> index 1fbb7531238b6..149d696feb520 100644
> --- a/include/linux/if_rmnet.h
> +++ b/include/linux/if_rmnet.h
> @@ -33,17 +33,16 @@ struct rmnet_map_dl_csum_trailer {
>
> struct rmnet_map_ul_csum_header {
> __be16 csum_start_offset;
> -#if defined(__LITTLE_ENDIAN_BITFIELD)
> - u16 csum_insert_offset:14;
> - u16 udp_ind:1;
> - u16 csum_enabled:1;
> -#elif defined (__BIG_ENDIAN_BITFIELD)
> - u16 csum_enabled:1;
> - u16 udp_ind:1;
> - u16 csum_insert_offset:14;
> -#else
> -#error "Please fix <asm/byteorder.h>"
> -#endif
> + __be16 csum_info; /* MAP_CSUM_UL_*_FMASK */
> } __aligned(1);
>
> +/* csum_info field:
> + * ENABLED: 1 = checksum computation requested
> + * UDP: 1 = UDP checksum (zero checkum means no checksum)
> + * OFFSET: where (offset in bytes) to insert computed checksum
> + */
> +#define MAP_CSUM_UL_OFFSET_FMASK GENMASK(13, 0)
> +#define MAP_CSUM_UL_UDP_FMASK GENMASK(14, 14)
> +#define MAP_CSUM_UL_ENABLED_FMASK GENMASK(15, 15)
> +
> #endif /* !(_LINUX_IF_RMNET_H_) */
> --
> 2.20.1
>
next prev parent reply other threads:[~2021-03-05 5:26 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-04 22:34 [PATCH net-next 0/6] net: qualcomm: rmnet: stop using C bit-fields Alex Elder
2021-03-04 22:34 ` [PATCH net-next 1/6] net: qualcomm: rmnet: mark trailer field endianness Alex Elder
2021-03-05 4:03 ` Bjorn Andersson
2021-03-04 22:34 ` [PATCH net-next 2/6] net: qualcomm: rmnet: simplify some byte order logic Alex Elder
2021-03-05 4:07 ` Bjorn Andersson
2021-03-05 21:02 ` Alex Elder
2021-03-04 22:34 ` [PATCH net-next 3/6] net: qualcomm: rmnet: kill RMNET_MAP_GET_*() accessor macros Alex Elder
2021-03-05 4:16 ` Bjorn Andersson
2021-03-04 22:34 ` [PATCH net-next 4/6] net: qualcomm: rmnet: use field masks instead of C bit-fields Alex Elder
2021-03-05 4:50 ` Bjorn Andersson
2021-03-04 22:34 ` [PATCH net-next 5/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum trailer Alex Elder
2021-03-05 4:54 ` Bjorn Andersson
2021-03-04 22:34 ` [PATCH net-next 6/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum header Alex Elder
2021-03-05 5:26 ` Bjorn Andersson [this message]
2021-03-05 20:48 ` Alex Elder
2021-03-05 6:22 ` kernel test robot
2021-03-05 12:59 ` Alex Elder
2021-03-04 22:43 ` [PATCH net-next 0/6] net: qualcomm: rmnet: stop using C bit-fields Alex Elder
2021-03-05 3:44 ` subashab
2021-03-05 4:51 ` Alex Elder
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