[PATCH dpdk v2] mbuf: fix strict aliasing error in allocator

[Stephen Hemminger]

On Wed, 25 Sep 2024 11:40:54 -0400
Robin Jarry <rjarry at redhat.com> wrote:

> From: Robin Jarry <rjarry at redhat.com>
> To: dev at dpdk.org
> Subject: [PATCH dpdk v2] mbuf: fix strict aliasing error in allocator
> Date: Wed, 25 Sep 2024 11:40:54 -0400
> 
> 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 <rjarry at redhat.com>

Thanks, union is safer than cast.

Reviewed-by: Stephen Hemminger <stephen at networkplumber.org>