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From: Robin Jarry <rjarry@redhat.com>
To: dev@dpdk.org
Subject: [PATCH dpdk v2] mbuf: fix strict aliasing error in allocator
Date: Wed, 25 Sep 2024 11:40:54 -0400
Message-ID: <20240925154053.80861-2-rjarry@redhat.com>
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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@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