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| author | Marco Elver <elver@google.com> | 2021-08-09 13:25:11 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-09-13 16:41:19 -0700 |
| commit | ade3a58b2d40555701143930ead3d44d0b52ca9e (patch) | |
| tree | cf682459e524acd2803d907d4473e23ab6f57db5 /kernel/kcsan | |
| parent | 80804284103ab95e1fe92f167af690ef4c9a6560 (diff) | |
| download | lwn-ade3a58b2d40555701143930ead3d44d0b52ca9e.tar.gz lwn-ade3a58b2d40555701143930ead3d44d0b52ca9e.zip | |
kcsan: test: Fix flaky test case
If CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n, then we may also see data
races between the writers only. If we get unlucky and never capture a
read-write data race, but only the write-write data races, then the
test_no_value_change* test cases may incorrectly fail.
The second problem is that the initial value needs to be reset, as
otherwise we might actually observe a value change at the start.
Fix it by also looking for the write-write data races, and resetting the
value to what will be written.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/kcsan')
| -rw-r--r-- | kernel/kcsan/kcsan_test.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c index d93f226327af..e282c1166373 100644 --- a/kernel/kcsan/kcsan_test.c +++ b/kernel/kcsan/kcsan_test.c @@ -493,17 +493,24 @@ static void test_concurrent_races(struct kunit *test) __no_kcsan static void test_novalue_change(struct kunit *test) { - const struct expect_report expect = { + const struct expect_report expect_rw = { .access = { { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, { test_kernel_read, &test_var, sizeof(test_var), 0 }, }, }; + const struct expect_report expect_ww = { + .access = { + { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + }, + }; bool match_expect = false; + test_kernel_write_nochange(); /* Reset value. */ begin_test_checks(test_kernel_write_nochange, test_kernel_read); do { - match_expect = report_matches(&expect); + match_expect = report_matches(&expect_rw) || report_matches(&expect_ww); } while (!end_test_checks(match_expect)); if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY)) KUNIT_EXPECT_FALSE(test, match_expect); @@ -518,17 +525,24 @@ static void test_novalue_change(struct kunit *test) __no_kcsan static void test_novalue_change_exception(struct kunit *test) { - const struct expect_report expect = { + const struct expect_report expect_rw = { .access = { { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, { test_kernel_read, &test_var, sizeof(test_var), 0 }, }, }; + const struct expect_report expect_ww = { + .access = { + { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE }, + }, + }; bool match_expect = false; + test_kernel_write_nochange_rcu(); /* Reset value. */ begin_test_checks(test_kernel_write_nochange_rcu, test_kernel_read); do { - match_expect = report_matches(&expect); + match_expect = report_matches(&expect_rw) || report_matches(&expect_ww); } while (!end_test_checks(match_expect)); KUNIT_EXPECT_TRUE(test, match_expect); } |