Commit 078a2ead authored by Justin Stitt's avatar Justin Stitt Committed by Shuah Khan
Browse files

selftests/rseq: fix kselftest Clang build warnings 

When building with Clang, I am getting many warnings from the selftests/rseq tree.

Here's one such example from rseq tree:
|  param_test.c:1234:10: error: address argument to atomic operation must be a pointer to _Atomic type ('intptr_t *' (aka 'long *') invalid)
|   1234 |         while (!atomic_load(&args->percpu_list_ptr)) {}
|        |                 ^           ~~~~~~~~~~~~~~~~~~~~~~
|  /usr/local/google/home/justinstitt/repos/tc-build/build/llvm/final/lib/clang/18/include/stdatomic.h:140:29: note: expanded from macro 'atomic_load'
|    140 | #define atomic_load(object) __c11_atomic_load(object, __ATOMIC_SEQ_CST)
|        |                             ^                 ~~~~~~

Use compiler builtins `__atomic_load_n()` and `__atomic_store_n()` with
accompanying __ATOMIC_ACQUIRE and __ATOMIC_RELEASE, respectively. This
will fix the warnings because the compiler builtins do not expect their
arguments to have _Atomic type. This should also make TSAN happier.

Link: https://github.com/ClangBuiltLinux/linux/issues/1698
Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/61


Suggested-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: default avatarJustin Stitt <justinstitt@google.com>
Reviewed-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: default avatarShuah Khan <skhan@linuxfoundation.org>
parent 18378b0e

tools/testing/selftests/rseq/param_test.c

+10 −10
Original line number Diff line number Diff line
@@ -1231,7 +1231,7 @@ void *test_membarrier_worker_thread(void *arg) 
	}



	/* Wait for initialization. */

	while (!atomic_load(&args->percpu_list_ptr)) {}

	while (!__atomic_load_n(&args->percpu_list_ptr, __ATOMIC_ACQUIRE)) {}



	for (i = 0; i < iters; ++i) {

		int ret;
@@ -1299,22 +1299,22 @@ void *test_membarrier_manager_thread(void *arg) 
	test_membarrier_init_percpu_list(&list_a);

	test_membarrier_init_percpu_list(&list_b);



	atomic_store(&args->percpu_list_ptr, (intptr_t)&list_a);

	__atomic_store_n(&args->percpu_list_ptr, (intptr_t)&list_a, __ATOMIC_RELEASE);



	while (!atomic_load(&args->stop)) {

	while (!__atomic_load_n(&args->stop, __ATOMIC_ACQUIRE)) {

		/* list_a is "active". */

		cpu_a = rand() % CPU_SETSIZE;

		/*

		 * As list_b is "inactive", we should never see changes

		 * to list_b.

		 */

		if (expect_b != atomic_load(&list_b.c[cpu_b].head->data)) {

		if (expect_b != __atomic_load_n(&list_b.c[cpu_b].head->data, __ATOMIC_ACQUIRE)) {

			fprintf(stderr, "Membarrier test failed\n");

			abort();

		}



		/* Make list_b "active". */

		atomic_store(&args->percpu_list_ptr, (intptr_t)&list_b);

		__atomic_store_n(&args->percpu_list_ptr, (intptr_t)&list_b, __ATOMIC_RELEASE);

		if (rseq_membarrier_expedited(cpu_a) &&

				errno != ENXIO /* missing CPU */) {

			perror("sys_membarrier");
@@ -1324,27 +1324,27 @@ void *test_membarrier_manager_thread(void *arg) 
		 * Cpu A should now only modify list_b, so the values

		 * in list_a should be stable.

		 */

		expect_a = atomic_load(&list_a.c[cpu_a].head->data);

		expect_a = __atomic_load_n(&list_a.c[cpu_a].head->data, __ATOMIC_ACQUIRE);



		cpu_b = rand() % CPU_SETSIZE;

		/*

		 * As list_a is "inactive", we should never see changes

		 * to list_a.

		 */

		if (expect_a != atomic_load(&list_a.c[cpu_a].head->data)) {

		if (expect_a != __atomic_load_n(&list_a.c[cpu_a].head->data, __ATOMIC_ACQUIRE)) {

			fprintf(stderr, "Membarrier test failed\n");

			abort();

		}



		/* Make list_a "active". */

		atomic_store(&args->percpu_list_ptr, (intptr_t)&list_a);

		__atomic_store_n(&args->percpu_list_ptr, (intptr_t)&list_a, __ATOMIC_RELEASE);

		if (rseq_membarrier_expedited(cpu_b) &&

				errno != ENXIO /* missing CPU*/) {

			perror("sys_membarrier");

			abort();

		}

		/* Remember a value from list_b. */

		expect_b = atomic_load(&list_b.c[cpu_b].head->data);

		expect_b = __atomic_load_n(&list_b.c[cpu_b].head->data, __ATOMIC_ACQUIRE);

	}



	test_membarrier_free_percpu_list(&list_a);
@@ -1401,7 +1401,7 @@ void test_membarrier(void) 
		}

	}



	atomic_store(&thread_args.stop, 1);

	__atomic_store_n(&thread_args.stop, 1, __ATOMIC_RELEASE);

	ret = pthread_join(manager_thread, NULL);

	if (ret) {

		errno = ret;