On Mon, May 21, 2018 at 10:01:18AM +0800, Andy Green wrote:
> /projects/lagopus/src/dpdk/build/include/rte_mbuf.h:
> In function 'rte_validate_tx_offload':
> /projects/lagopus/src/dpdk/build/include/rte_mbuf.h:
> 2112:19: warning: conversion to 'uint64_t'
> {aka 'long unsigned int'} from 'int' may change the
> sign of the result [-Wsign-conversion]
> inner_l3_offset += m->outer_l2_len + m->outer_l3_len;
> ^~
>
> uint64_t inner_l3_offset...
>
> /* fields for TX offloading of tunnels */
> uint64_t outer_l3_len:9; /**< Outer L3 (IP) Hdr Length. */
> uint64_t outer_l2_len:7; /**< Outer L2 (MAC) Hdr Length. */
>
> We want to do the arithmetic entirely in uint64_t
> space, but there is an implicit demotion to int created by
> the +=. Remove the +=.
>
> Fixes: 4fb7e803eb ("ethdev: add Tx preparation")
> Signed-off-by: Andy Green <a...@warmcat.com>
> ---
> lib/librte_mbuf/rte_mbuf.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
Fix looks ok, but given that it's non-obvious why += doesn't work, I think
it would be good to put a comment in explaining it. Otherwise I could see
someone changing this back in a later patch, because the problem doesn't
arise with regular DPDK compiles
Acked-by: Bruce Richardson <bruce.richard...@intel.com>
