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author | 2022-03-10 16:37:21 -0800 | |
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committer | 2022-03-11 22:18:13 +0100 | |
commit | d3b351f65bf42ccda1f686de3ccb21ea1a0c4f5a (patch) | |
tree | dff0fa15f56becacd32895844eecc96bcb3e569c /tools/testing/selftests/bpf | |
parent | selftests/bpf: Add a test for maximum packet size in xdp_do_redirect (diff) | |
download | linux-d3b351f65bf42ccda1f686de3ccb21ea1a0c4f5a.tar.gz linux-d3b351f65bf42ccda1f686de3ccb21ea1a0c4f5a.tar.bz2 linux-d3b351f65bf42ccda1f686de3ccb21ea1a0c4f5a.zip |
selftests/bpf: Fix a clang compilation error for send_signal.c
Building selftests/bpf with latest clang compiler (clang15 built
from source), I hit the following compilation error:
/.../prog_tests/send_signal.c:43:16: error: variable 'j' set but not used [-Werror,-Wunused-but-set-variable]
volatile int j = 0;
^
1 error generated.
The problem also exists with clang13 and clang14. clang12 is okay.
In send_signal.c, we have the following code ...
volatile int j = 0;
[...]
for (int i = 0; i < 100000000 && !sigusr1_received; i++)
j /= i + 1;
... to burn CPU cycles so bpf_send_signal() helper can be tested
in NMI mode.
Slightly changing 'j /= i + 1' to 'j /= i + j + 1' or 'j++' can
fix the problem. Further investigation indicated this should be
a clang bug ([1]). The upstream fix will be proposed later. But it
is a good idea to workaround the issue to unblock people who build
kernel/selftests with clang.
[1] https://discourse.llvm.org/t/strange-clang-unused-but-set-variable-error-with-volatile-variables/60841
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220311003721.2177170-1-yhs@fb.com
Diffstat (limited to 'tools/testing/selftests/bpf')
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/send_signal.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c index def50f1c5c31..d71226e34c34 100644 --- a/tools/testing/selftests/bpf/prog_tests/send_signal.c +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c @@ -65,7 +65,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, /* wait a little for signal handler */ for (int i = 0; i < 100000000 && !sigusr1_received; i++) - j /= i + 1; + j /= i + j + 1; buf[0] = sigusr1_received ? '2' : '0'; ASSERT_EQ(sigusr1_received, 1, "sigusr1_received"); |