[PATCH] selftests/futex: load atomic values before harness comparisons

[PATCH] selftests/futex: load atomic values before harness comparisons

[Sasha Levin]

Clang 21 rejects the harness comparison because typeof(*futex) preserves
the atomic qualification. Load the value explicitly in the three affected
assertions so the harness compares unsigned integers. Atomic access and
its existing sequentially consistent ordering are preserved.

The baseline produces three invalid-operands errors. The complete futex
suite builds with Clang 21 and GCC 14 after the change.

Fixes: 608323bf7bb8 ("selftests: futex: Add tests for robust release operations")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/testing/selftests/futex/functional/robust_list.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/robust_list.c b/tools/testing/selftests/futex/functional/robust_list.c
index 87217c5493619..895e6cfe59bcd 100644
--- a/tools/testing/selftests/futex/functional/robust_list.c
+++ b/tools/testing/selftests/futex/functional/robust_list.c
@@ -669,7 +669,7 @@ TEST_F(vdso_unlock, test_robust_try_unlock_uncontended)
 	ret = self->vdso(futex, tid, &head.list_op_pending);
 
 	ASSERT_EQ(ret, tid);
-	ASSERT_EQ(*futex, 0);
+	ASSERT_EQ(atomic_load(futex), 0);
 
 	/* Check only the lower 32 bits for the 32-bit entry point */
 	if (variant->is_32) {
@@ -709,7 +709,7 @@ TEST_F(vdso_unlock, test_robust_try_unlock_contended)
 	ret = self->vdso(futex, tid, &head.list_op_pending);
 
 	ASSERT_EQ(ret, tid | FUTEX_WAITERS);
-	ASSERT_EQ(*futex, tid | FUTEX_WAITERS);
+	ASSERT_EQ(atomic_load(futex), tid | FUTEX_WAITERS);
 	ASSERT_EQ(head.list_op_pending, &lock.list);
 }
 
@@ -793,7 +793,7 @@ TEST_F(futex_op, test_futex_robust_unlock)
 				      &head.list_op_pending, variant->val3);
 
 	ASSERT_EQ(ret, 0);
-	ASSERT_EQ(*futex, 0);
+	ASSERT_EQ(atomic_load(futex), 0);
 
 	if (variant->op & FUTEX_ROBUST_LIST32) {
 		exp = (uint64_t)(unsigned long)&lock.list;

base-commit: 4eb2586bd40db27d77cc5b724ca9386ed0c71d53
-- 
2.53.0

Re: [PATCH] selftests/futex: load atomic values before harness comparisons

[Sasha Levin]

Ping, this still applies on 7.4-rc1. The clang jobs in KernelCI still
fail to build futex/functional/robust_list.c with the three
invalid-operands errors.

-- 
Thanks,
Sasha

Re: [PATCH] selftests/futex: load atomic values before harness comparisons

[André Almeida]

Em 14/10/2026 17:01, Sasha Levin escreveu:
> Clang 21 rejects the harness comparison because typeof(*futex) preserves
> the atomic qualification. Load the value explicitly in the three affected
> assertions so the harness compares unsigned integers. Atomic access and
> its existing sequentially consistent ordering are preserved.
> 
> The baseline produces three invalid-operands errors. The complete futex
> suite builds with Clang 21 and GCC 14 after the change.
> 
> Fixes: 608323bf7bb8 ("selftests: futex: Add tests for robust release operations")
> Signed-off-by: Sasha Levin <sashal@kernel.org>

Reviewed-by: André Almeida <andrealmeid@igalia.com>