* [PATCH bpf-next] selftests/bpf: fix nanosleep for real this time
@ 2020-03-13 23:35 Andrii Nakryiko
2020-03-14 0:05 ` [Potential Spoof] " Martin KaFai Lau
0 siblings, 1 reply; 3+ messages in thread
From: Andrii Nakryiko @ 2020-03-13 23:35 UTC (permalink / raw)
To: bpf, netdev, ast, daniel; +Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko
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@fb.com>
---
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,
+ };
+
+ return syscall(__NR_nanosleep, &ts, NULL);
}
static bool should_run(struct test_selector *sel, int num, const char *name)
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Potential Spoof] [PATCH bpf-next] selftests/bpf: fix nanosleep for real this time
2020-03-13 23:35 [PATCH bpf-next] selftests/bpf: fix nanosleep for real this time Andrii Nakryiko
@ 2020-03-14 0:05 ` Martin KaFai Lau
2020-03-14 0:10 ` Andrii Nakryiko
0 siblings, 1 reply; 3+ messages in thread
From: Martin KaFai Lau @ 2020-03-14 0:05 UTC (permalink / raw)
To: Andrii Nakryiko; +Cc: bpf, netdev, ast, daniel, andrii.nakryiko, kernel-team
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@fb.com>
> ---
> 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?
> + };
> +
> + return syscall(__NR_nanosleep, &ts, NULL);
> }
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Potential Spoof] [PATCH bpf-next] selftests/bpf: fix nanosleep for real this time
2020-03-14 0:05 ` [Potential Spoof] " Martin KaFai Lau
@ 2020-03-14 0:10 ` Andrii Nakryiko
0 siblings, 0 replies; 3+ messages in thread
From: Andrii Nakryiko @ 2020-03-14 0:10 UTC (permalink / raw)
To: Martin KaFai Lau
Cc: Andrii Nakryiko, bpf, Networking, Alexei Starovoitov,
Daniel Borkmann, Kernel Team
On Fri, Mar 13, 2020 at 5:05 PM Martin KaFai Lau <kafai@fb.com> 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@fb.com>
> > ---
> > 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);
> > }
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-03-13 23:35 [PATCH bpf-next] selftests/bpf: fix nanosleep for real this time Andrii Nakryiko
2020-03-14 0:05 ` [Potential Spoof] " Martin KaFai Lau
2020-03-14 0:10 ` Andrii Nakryiko
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