Re: [PATCH net-next 2/6] net: qualcomm: rmnet: simplify some byte order logic
From: Bjorn Andersson <hidden>
Date: 2021-03-05 04:07:18
Also in:
lkml
On Thu 04 Mar 16:34 CST 2021, Alex Elder wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- .../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 <redacted> Regards, Bjorn
quoted hunk ↗ jump to hunk
- (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