From 01ac23460c36927e019473e71b582223ad6b79c5 Mon Sep 17 00:00:00 2001 From: Guduri Prathyusha Date: Fri, 3 Nov 2017 16:13:51 +0530 Subject: [PATCH] examples/l3fwd: fix aliasing in port grouping With -f-strict-aliasing enabled by default from -O2, gcc > 5.x gives undefined behavior in port_groupx4 in ARM. 'pn' and 'pnum' are two different pointers pointing to same chunk of memory and with -f-strict-aliasing the pointers are assumed to be pointing to different memory and compiler reorders instructions that depend on pnum and pn. This breaks port grouping algorithm. This patch eliminates the above problem by introducing a compiler barrier between the instructions that depend on pnum, pn and lp. Fixes: 569b290cdb36 ("examples/l3fwd: add NEON implementation") Cc: stable@dpdk.org Signed-off-by: Guduri Prathyusha Acked-by: Jerin Jacob Acked-by: Jianbo Liu --- examples/l3fwd/l3fwd_neon.h | 1 + 1 file changed, 1 insertion(+) diff --git a/examples/l3fwd/l3fwd_neon.h b/examples/l3fwd/l3fwd_neon.h index 4bc1613943..b319b5a92a 100644 --- a/examples/l3fwd/l3fwd_neon.h +++ b/examples/l3fwd/l3fwd_neon.h @@ -114,6 +114,7 @@ port_groupx4(uint16_t pn[FWDSTEP + 1], uint16_t *lp, uint16x8_t dp1, /* update last port counter. */ lp[0] += gptbl[v].lpv; + rte_compiler_barrier(); /* if dest port value has changed. */ if (v != GRPMSK) { -- 2.20.1