[dpdk-dev] [PATCH 1/1] ip_frag: fix creating ipv6 fragment extension header

Ananyev, Konstantin konstantin.ananyev at intel.com
Fri Sep 4 17:51:16 CEST 2015


Hi Piotr,

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Piotr
> Sent: Wednesday, September 02, 2015 3:13 PM
> To: dev at dpdk.org
> Subject: [dpdk-dev] [PATCH 1/1] ip_frag: fix creating ipv6 fragment extension header
> 
> From: Piotr Azarewicz <piotrx.t.azarewicz at intel.com>
> 
> Previous implementation won't work on every environment. The order of
> allocation of bit-fields within a unit (high-order to low-order or
> low-order to high-order) is implementation-defined.
> Solution: used bytes instead of bit fields.

Seems like right thing to do to me.
Though I think we also should replace:
union {
                struct {
                        uint16_t frag_offset:13; /**< Offset from the start of the packet */
                        uint16_t reserved2:2; /**< Reserved */
                        uint16_t more_frags:1;
                        /**< 1 if more fragments left, 0 if last fragment */
                };
                uint16_t frag_data;
                /**< union of all fragmentation data */
        }; 

With just: 
uint16_t frag_data;
 and probably provide macros to read/set fragment_offset and more_flags values.
Otherwise people might keep using the wrong layout.
Konstantin

> 
> Signed-off-by: Piotr Azarewicz <piotrx.t.azarewicz at intel.com>
> ---
>  lib/librte_ip_frag/rte_ipv6_fragmentation.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_ip_frag/rte_ipv6_fragmentation.c b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
> index 0e32aa8..7342421 100644
> --- a/lib/librte_ip_frag/rte_ipv6_fragmentation.c
> +++ b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
> @@ -65,10 +65,8 @@ __fill_ipv6hdr_frag(struct ipv6_hdr *dst,
> 
>  	fh = (struct ipv6_extension_fragment *) ++dst;
>  	fh->next_header = src->proto;
> -	fh->reserved1   = 0;
> -	fh->frag_offset = rte_cpu_to_be_16(fofs);
> -	fh->reserved2   = 0;
> -	fh->more_frags  = rte_cpu_to_be_16(mf);
> +	fh->reserved1 = 0;
> +	fh->frag_data = rte_cpu_to_be_16((fofs & ~IPV6_HDR_FO_MASK) | mf);
>  	fh->id = 0;
>  }
> 
> --
> 1.7.9.5



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