On Sat, Sep 9, 2023 at 5:37 AM Mathieu Desnoyers
<mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
> On 9/8/23 19:03, Justin Stitt wrote:
> > Hi,
> >
> > I am experiencing many warnings when trying to build tools/testing/selftests.
> >
> > 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)
> > | | ^ ~~~~~~
> >
> > I added the _Atomic type in various locations to silence _all_ (10) of these
> > warnings. I'm wondering, though, perhaps the absence of these _Atomic
> > types in the first place is on purpose? Am I on the right track to fix
> > these warnings without damaging the legitimacy of the tests at hand?
> >
> > I'd like some feedback about where to go from here and if others are
> > experiencing the same issues. Thanks!
> >
> > FWIW here's my specific build incantation on Clang-18 (49d41de57896e935cd5726719c5208bce22694ae):
> > $ make LLVM=1 -j128 ARCH=x86_64 mrproper headers defconfig kselftest-merge
> > $ make LLVM=1 ARCH=x86_64 -C tools/testing/selftests
>
> I should have used the __atomic_load_n() compiler builtin rather than
> atomic_load(), mainly because it does not require the _Atomic annotation
> to each type it touches.
Would you like me to send a patch in with this change?
>
> Thanks,
>
> Mathieu
>
>
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1698
> > Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/61
> > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
> > ---
> > tools/testing/selftests/rseq/param_test.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/testing/selftests/rseq/param_test.c b/tools/testing/selftests/rseq/param_test.c
> > index bf951a490bb4..94802aeed2c6 100644
> > --- a/tools/testing/selftests/rseq/param_test.c
> > +++ b/tools/testing/selftests/rseq/param_test.c
> > @@ -356,7 +356,7 @@ struct inc_thread_test_data {
> > };
> >
> > struct percpu_list_node {
> > - intptr_t data;
> > + _Atomic intptr_t data;
> > struct percpu_list_node *next;
> > };
> >
> > @@ -1212,8 +1212,8 @@ static int set_signal_handler(void)
> > /* Test MEMBARRIER_CMD_PRIVATE_RESTART_RSEQ_ON_CPU membarrier command. */
> > #ifdef TEST_MEMBARRIER
> > struct test_membarrier_thread_args {
> > - int stop;
> > - intptr_t percpu_list_ptr;
> > + _Atomic int stop;
> > + _Atomic intptr_t percpu_list_ptr;
> > };
> >
> > /* Worker threads modify data in their "active" percpu lists. */
> > @@ -1240,7 +1240,7 @@ void *test_membarrier_worker_thread(void *arg)
> > int cpu = get_current_cpu_id();
> >
> > ret = rseq_offset_deref_addv(RSEQ_MO_RELAXED, RSEQ_PERCPU,
> > - &args->percpu_list_ptr,
> > + (intptr_t*)&args->percpu_list_ptr,
> > sizeof(struct percpu_list_entry) * cpu, 1, cpu);
> > } while (rseq_unlikely(ret));
> > }
> >
> > ---
> > base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> > change-id: 20230908-kselftest-param_test-c-1763b62e762f
> >
> > Best regards,
> > --
> > Justin Stitt <justinstitt@xxxxxxxxxx>
> >
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> https://www.efficios.com
>
