On Wed, 25 Sep 2024 17:21:12 +0200 Morten Brørup <m...@smartsharesystems.com> wrote:
> From: Morten Brørup <m...@smartsharesystems.com> > To: "Robin Jarry" <rja...@redhat.com>, <dev@dpdk.org> > Subject: RE: [PATCH dpdk] mbuf: fix strict aliasing error in allocator > Date: Wed, 25 Sep 2024 17:21:12 +0200 > > > From: Robin Jarry [mailto:rja...@redhat.com] > > Sent: Wednesday, 25 September 2024 10.00 > > > > 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 changing the type of the returned variable. > > > > Signed-off-by: Robin Jarry <rja...@redhat.com> > > --- > > lib/mbuf/rte_mbuf.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h > > index babe16c72ccb..bab1fb94d41d 100644 > > --- a/lib/mbuf/rte_mbuf.h > > +++ b/lib/mbuf/rte_mbuf.h > > @@ -595,9 +595,9 @@ __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; > > + void *m; > > > > - if (rte_mempool_get(mp, (void **)&m) < 0) > > + if (rte_mempool_get(mp, &m) < 0) > > return NULL; > > __rte_mbuf_raw_sanity_check(m); > > return m; > > Suggest: > __rte_mbuf_raw_sanity_check((struct rte_mbuf *)m); > return (struct rte_mbuf *)m; Another way to avoid the warning would be to use a union?
