> -----Original Message-----
> From: Robin Jarry <rja...@redhat.com>
> Sent: Wednesday, September 25, 2024 6:41 PM
> To: dev@dpdk.org
> Subject: [PATCH dpdk v2] mbuf: fix strict aliasing error in allocator
>
> When building an application with -fstrict-aliasing -Wstrict-aliasing=2,
> we get errors triggered by rte_mbuf_raw_alloc() which is called inline
> from rte_pktmbuf_alloc().
>
> ../dpdk/lib/mbuf/rte_mbuf.h: In function ‘rte_mbuf_raw_alloc’:
> ../dpdk/lib/mbuf/rte_mbuf.h:600:42: error: dereferencing type-punned
> pointer might break strict-aliasing rules [-Werror=strict-aliasing]
> 600 | if (rte_mempool_get(mp, (void **)&m) < 0)
> | ^~
>
> Avoid incorrect casting by using an inline union variable.
>
> Signed-off-by: Robin Jarry <rja...@redhat.com>
> ---
>
> Notes:
> v2: use inline union to fix -Wincompatible-pointer-types
>
> lib/mbuf/rte_mbuf.h | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h
> index babe16c72ccb..0d2e0e64b3ce 100644
> --- a/lib/mbuf/rte_mbuf.h
> +++ b/lib/mbuf/rte_mbuf.h
> @@ -595,12 +595,15 @@ __rte_mbuf_raw_sanity_check(__rte_unused const
> struct rte_mbuf *m)
> */
> static inline struct rte_mbuf *rte_mbuf_raw_alloc(struct rte_mempool *mp)
> {
> - struct rte_mbuf *m;
> + union {
> + void *ptr;
> + struct rte_mbuf *m;
> + } ret;
>
> - if (rte_mempool_get(mp, (void **)&m) < 0)
> + if (rte_mempool_get(mp, &ret.ptr) < 0)
> return NULL;
> - __rte_mbuf_raw_sanity_check(m);
> - return m;
> + __rte_mbuf_raw_sanity_check(ret.m);
> + return ret.m;
> }
>
> /**
> --
> 2.46.1
Hello,
We noticed the failure in ci/iol-mellanox-Performance and ran a few performance
test cases on NVIDIA hardware and found no regressions.
Additionally ran build and functional test cases that also passed.
Tested-by: Ali Alnubani <alia...@nvidia.com>
Regards,
Ali
