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Date:   Thu, 14 Apr 2022 22:47:06 +0000
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>
From:   Alexander Lobakin <alobakin@pm.me>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
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        Namhyung Kim <namhyung@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
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        Jakub Kicinski <kuba@kernel.org>,
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        Jonathan Lemon <jonathan.lemon@gmail.com>,
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Reply-To: Alexander Lobakin <alobakin@pm.me>
Subject: [PATCH bpf-next 10/11] samples: bpf: fix -Wsequence-point
Message-ID: <20220414223704.341028-11-alobakin@pm.me>
In-Reply-To: <20220414223704.341028-1-alobakin@pm.me>
References: <20220414223704.341028-1-alobakin@pm.me>
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In some libc implementations, CPU_SET() may utilize its first
argument several times. When combined with a post-increment, it
leads to:

samples/bpf/test_lru_dist.c:233:36: warning: operation on 'next_to_try' may=
 be undefined [-Wsequence-point]
  233 |                 CPU_SET(next_to_try++, &cpuset);
      |                                    ^

Split the sentence into two standalone operations to fix this.

Fixes: 5db58faf989f ("bpf: Add tests for the LRU bpf_htab")
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
 samples/bpf/test_lru_dist.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/samples/bpf/test_lru_dist.c b/samples/bpf/test_lru_dist.c
index be98ccb4952f..191643ec501e 100644
--- a/samples/bpf/test_lru_dist.c
+++ b/samples/bpf/test_lru_dist.c
@@ -229,7 +229,8 @@ static int sched_next_online(int pid, int next_to_try)

 =09while (next_to_try < nr_cpus) {
 =09=09CPU_ZERO(&cpuset);
-=09=09CPU_SET(next_to_try++, &cpuset);
+=09=09CPU_SET(next_to_try, &cpuset);
+=09=09next_to_try++;
 =09=09if (!sched_setaffinity(pid, sizeof(cpuset), &cpuset))
 =09=09=09break;
 =09}
--
2.35.2