On Fri, Mar 13, 2020 at 5:05 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> On Fri, Mar 13, 2020 at 04:35:35PM -0700, Andrii Nakryiko wrote:
> > Amazingly, some libc implementations don't call __NR_nanosleep syscall from
> > their nanosleep() APIs. Hammer it down with explicit syscall() call and never
> > get back to it again. Also simplify code for timespec initialization.
> >
> > I verified that nanosleep is called w/ printk and in exactly same Linux image
> > that is used in Travis CI. So it should both sleep and call correct syscall.
> >
> > Fixes: 4e1fd25d19e8 ("selftests/bpf: Fix usleep() implementation")
> > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> > ---
> > tools/testing/selftests/bpf/test_progs.c | 16 ++++++----------
> > 1 file changed, 6 insertions(+), 10 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> > index f85a06512541..6956d722a463 100644
> > --- a/tools/testing/selftests/bpf/test_progs.c
> > +++ b/tools/testing/selftests/bpf/test_progs.c
> > @@ -35,16 +35,12 @@ struct prog_test_def {
> > */
> > int usleep(useconds_t usec)
> > {
> > - struct timespec ts;
> > -
> > - if (usec > 999999) {
> > - ts.tv_sec = usec / 1000000;
> > - ts.tv_nsec = usec % 1000000;
> > - } else {
> > - ts.tv_sec = 0;
> > - ts.tv_nsec = usec;
> > - }
> > - return nanosleep(&ts, NULL);
> > + struct timespec ts = {
> > + .tv_sec = usec / 1000000,
> > + .tv_nsec = usec % 1000000,
> usec is in micro and tv_nsec is in nano?
>
Yes, this is implementation of usleep() (microsecond sleep), so usec
is microseconds. We call nanosleep internally, though, which accepts
seconds and nanoseconds units. Did I mess up math here?
But either way, sending v2, there is another place we explicitly are
calling nanosleep as well, fixing that one as well.
> > + };
> > +
> > + return syscall(__NR_nanosleep, &ts, NULL);
> > }
> >
