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authorMarco Elver <elver@google.com>2021-08-09 13:25:11 +0200
committerPaul E. McKenney <paulmck@kernel.org>2021-09-13 16:41:19 -0700
commitade3a58b2d40555701143930ead3d44d0b52ca9e (patch)
treecf682459e524acd2803d907d4473e23ab6f57db5 /kernel/kcsan
parent80804284103ab95e1fe92f167af690ef4c9a6560 (diff)
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.c22
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);
}