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 2/6] net: qualcomm: rmnet: simplify some byte order logic
Date: Thu, 4 Mar 2021 22:07:13 -0600 [thread overview]
Message-ID: <YEGucXIUQ59UcLrJ@builder.lan> (raw)
In-Reply-To: <20210304223431.15045-3-elder@linaro.org>
On Thu 04 Mar 16:34 CST 2021, Alex Elder wrote:
> In rmnet_map_ipv4_ul_csum_header() and rmnet_map_ipv6_ul_csum_header()
> the offset within a packet at which checksumming should commence is
> calculated. This calculation involves byte swapping and a forced type
> conversion that makes it hard to understand.
>
> Simplify this by computing the offset in host byte order, then
> converting the result when assigning it into the header field.
>
> Signed-off-by: Alex Elder <elder@linaro.org>
> ---
> .../ethernet/qualcomm/rmnet/rmnet_map_data.c | 22 ++++++++++---------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> index 21d38167f9618..bd1aa11c9ce59 100644
> --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
> @@ -197,12 +197,13 @@ rmnet_map_ipv4_ul_csum_header(void *iphdr,
> struct rmnet_map_ul_csum_header *ul_header,
> struct sk_buff *skb)
> {
> - struct iphdr *ip4h = (struct iphdr *)iphdr;
> - __be16 *hdr = (__be16 *)ul_header, offset;
> + __be16 *hdr = (__be16 *)ul_header;
> + struct iphdr *ip4h = iphdr;
> + u16 offset;
> +
> + offset = skb_transport_header(skb) - (unsigned char *)iphdr;
> + ul_header->csum_start_offset = htons(offset);
>
> - offset = htons((__force u16)(skb_transport_header(skb) -
Just curious, why does this require a __force, or even a cast?
Regardless, your proposed way of writing it is easier to read.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Regards,
Bjorn
> - (unsigned char *)iphdr));
> - ul_header->csum_start_offset = offset;
> ul_header->csum_insert_offset = skb->csum_offset;
> ul_header->csum_enabled = 1;
> if (ip4h->protocol == IPPROTO_UDP)
> @@ -239,12 +240,13 @@ rmnet_map_ipv6_ul_csum_header(void *ip6hdr,
> struct rmnet_map_ul_csum_header *ul_header,
> struct sk_buff *skb)
> {
> - struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr;
> - __be16 *hdr = (__be16 *)ul_header, offset;
> + __be16 *hdr = (__be16 *)ul_header;
> + struct ipv6hdr *ip6h = ip6hdr;
> + u16 offset;
> +
> + offset = skb_transport_header(skb) - (unsigned char *)ip6hdr;
> + ul_header->csum_start_offset = htons(offset);
>
> - offset = htons((__force u16)(skb_transport_header(skb) -
> - (unsigned char *)ip6hdr));
> - ul_header->csum_start_offset = offset;
> ul_header->csum_insert_offset = skb->csum_offset;
> ul_header->csum_enabled = 1;
>
> --
> 2.20.1
>
next prev parent reply other threads:[~2021-03-05 4:07 UTC|newest]
Thread overview: 18+ 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 [this message]
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
2021-03-05 20:48 ` 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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