Re: [PATCH v4 1/2] selftests/clone3: Fix broken test under !CONFIG_TIME_NS

[Tiezhu Yang]

On 06/06/2023 04:18 PM, Thomas Gleixner wrote:
> On Mon, Jun 05 2023 at 20:33, Tiezhu Yang wrote:
> > When execute the following command to test clone3 on LoongArch:
> >
> >   # cd tools/testing/selftests/clone3 && make && ./clone3
> >
> > we can see the following error info:
> >
> >   # [5719] Trying clone3() with flags 0x80 (size 0)
> >   # Invalid argument - Failed to create new process
> >   # [5719] clone3() with flags says: -22 expected 0
> >   not ok 18 [5719] Result (-22) is different than expected (0)
> >
> > This is because if CONFIG_TIME_NS is not set, but the flag
> > CLONE_NEWTIME (0x80) is used to clone a time namespace, it
> > will return -EINVAL in copy_time_ns().
> >
> > Here is the related code in include/linux/time_namespace.h:
> >
> >   #ifdef CONFIG_TIME_NS
> >   ...
> >   struct time_namespace *copy_time_ns(unsigned long flags,
> > 				      struct user_namespace *user_ns,
> > 				      struct time_namespace *old_ns);
> >   ...
> >   #else
> >   ...
> >   static inline
> >   struct time_namespace *copy_time_ns(unsigned long flags,
> > 				      struct user_namespace *user_ns,
> > 				      struct time_namespace *old_ns)
> >   {
> > 	  if (flags & CLONE_NEWTIME)
> > 		  return ERR_PTR(-EINVAL);
> >
> > 	  return old_ns;
> >   }
> >   ...
> >   #endif
>
> There is really no point in copying that code into the changelog. The
> textual explanation that it returns -EINVAL is good enough.

OK, let me remove the code in the commit message.

> > Here is the complete call stack:
> >
> >   clone3()
> >     kernel_clone()
> >       copy_process()
> >         copy_namespaces()
> >           create_new_namespaces()
> >             copy_time_ns()
> >               clone_time_ns()
>
> Uninteresting too.

Will remove it too.

> > If kernel does not support CONFIG_TIME_NS, /proc/self/ns/time
> > will be not exist, and then we should skip clone3() test with
> > CLONE_NEWTIME.
>
> Correct.
>
> > With this patch under !CONFIG_TIME_NS:
> >
> >   # cd tools/testing/selftests/clone3 && make && ./clone3
> >   ...
> >   # Time namespaces are not supported
> >   ok 18 # SKIP Skipping clone3() with CLONE_NEWTIME
> >   # Totals: pass:17 fail:0 xfail:0 xpass:0 skip:1 error:0
>
> > Fixes: 515bddf0ec41 ("selftests/clone3: test clone3 with CLONE_NEWTIME")
> > Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> > ---
> >  tools/testing/selftests/clone3/clone3.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
> > index e495f89..c721f8a 100644
> > --- a/tools/testing/selftests/clone3/clone3.c
> > +++ b/tools/testing/selftests/clone3/clone3.c
> > @@ -196,7 +196,12 @@ int main(int argc, char *argv[])
> >  			CLONE3_ARGS_NO_TEST);
> >
> >  	/* Do a clone3() in a new time namespace */
> > -	test_clone3(CLONE_NEWTIME, 0, 0, CLONE3_ARGS_NO_TEST);
> > +	if (access("/proc/self/ns/time", F_OK) == 0) {
> > +		test_clone3(CLONE_NEWTIME, 0, 0, CLONE3_ARGS_NO_TEST);
> > +	} else {
> > +		ksft_print_msg("Time namespaces are not supported\n");
> > +		ksft_test_result_skip("Skipping clone3() with CLONE_NEWTIME\n");
> > +	}
>
> Patch looks good otherwise.

Thank you, I will send v5 on Friday with updated commit message
if no more comments.

Thanks,
Tiezhu