[lttng-dev] [PATCH lttng-tools 2/2] Tests: select_poll_epoll: Add support for _time64

[Alistair Francis]

On Wed, Oct 12, 2022 at 11:19 PM Jérémie Galarneau
<jeremie.galarneau at efficios.com> wrote:
>
> On Fri, Oct 07, 2022 at 10:39:18AM +1000, Alistair Francis via lttng-dev wrote:
>
> Hi Alistair,
>
> The first patch is good, I'll merge it in master.
> Some comments on this patch follow.

Thanks!

>
> > From: Alistair Francis <alistair.francis at wdc.com>
> >
> > Add support for the  64-bit time_t syscalls SYS_ppoll_time64
> > and SYS_pselect6_time64.
> >
> > These are the syscalls that exist 32-bit platforms since the 5.1 kernel.
> > 32-bit platforms with a 64-bit time_t only have these and don't have the
> > original syscalls (such as 32-bit RISC-V).
> >
> > Fixes: https://github.com/lttng/lttng-tools/pull/162
> > Signed-off-by: Alistair Francis <alistair.francis at wdc.com>
> > ---
> >  tests/regression/kernel/select_poll_epoll.cpp | 53 +++++++++++++++++++
> >  1 file changed, 53 insertions(+)
> >
> > diff --git a/tests/regression/kernel/select_poll_epoll.cpp b/tests/regression/kernel/select_poll_epoll.cpp
> > index c0b688217..4a6d394f4 100644
> > --- a/tests/regression/kernel/select_poll_epoll.cpp
> > +++ b/tests/regression/kernel/select_poll_epoll.cpp
> > @@ -5,6 +5,7 @@
> >   *
> >   */
> >
> > +#include <errno.h>
> >  #include <fcntl.h>
> >  #include <limits.h>
> >  #include <poll.h>
> > @@ -456,8 +457,22 @@ void ppoll_fds_buffer_overflow(
> >       ufds[0].fd = wait_fd;
> >       ufds[0].events = POLLIN|POLLPRI;
> >
> > +#ifdef SYS_ppoll_time64
> > +     /*
> > +      * As there is no timeout value, we don't convert to/from
> > +      * 64/32-bit time_t.
> > +      */
> > +     ret = syscall(SYS_ppoll_time64, ufds, 100, NULL, NULL);
> > +     if (ret == 0 || errno != ENOSYS) {
> > +             goto ppoll_fds_buffer_overflow_done;
> > +     }
> > +#endif
> > +
>
> This results in the following warning when building for an architecture
> that doesn't have SYS_ppoll_time64 defined:
>
> label ‘ppoll_fds_buffer_overflow_done’ defined but not used [-Wunused-label]
> ppoll_fds_buffer_overflow_done:
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> select_poll_epoll.cpp: In function ‘void ppoll_fds_ulong_max(FILE*)’:

Argh, I'll fix this

>
>
> Also, it is my understanding that both syscalls can be available on some
> platforms. In that case, it would make sense to add them as separate
> tests and skip tests that target non-existant syscalls.

So all 32-bit platforms since the 5.1 (or 5.4?) kernel have both syscalls.

>From my understanding the original syscalls will be removed on 32-bit
platforms at some point (before 2038) and there will only be *_time64
variants.

If you want I can copy the tests to test both syscall types, but I
don't think that's necessary.

Alistair