Re: [PATCHv3 bpf-next 3/9] selftests/bpf: Use only stdout in un/load_bpf_testmod functions

[Jiri Olsa <olsajiri@gmail.com>]

On Tue, Feb 07, 2023 at 08:41:38AM -0600, David Vernet wrote:
> On Fri, Feb 03, 2023 at 05:23:30PM +0100, Jiri Olsa wrote:
> > We are about to use un/load_bpf_testmod functions in couple tests
> > and it's better  to print output to stdout,  so it's aligned with
> > tests ASSERT macros output, which use stdout as well.
> > 
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> 
> Acked-by: David Vernet <void@manifault.com>
> 
> Should we remove FILE *stderr from struct test_env? Seems like it might
> be prudent if using it can actually cause a mismatch between testcase
> output and the test runner?

we still seem to use stderr in few places, not sure if it's
in the output hijack window.. I'll try to check

jirka

> 
> > ---
> >  tools/testing/selftests/bpf/testing_helpers.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
> > index 3a9e7e8e5b14..fd22c64646fc 100644
> > --- a/tools/testing/selftests/bpf/testing_helpers.c
> > +++ b/tools/testing/selftests/bpf/testing_helpers.c
> > @@ -244,14 +244,14 @@ static int delete_module(const char *name, int flags)
> >  void unload_bpf_testmod(bool verbose)
> >  {
> >  	if (kern_sync_rcu())
> > -		fprintf(stderr, "Failed to trigger kernel-side RCU sync!\n");
> > +		fprintf(stdout, "Failed to trigger kernel-side RCU sync!\n");
> >  	if (delete_module("bpf_testmod", 0)) {
> >  		if (errno == ENOENT) {
> >  			if (verbose)
> >  				fprintf(stdout, "bpf_testmod.ko is already unloaded.\n");
> >  			return;
> >  		}
> > -		fprintf(stderr, "Failed to unload bpf_testmod.ko from kernel: %d\n", -errno);
> > +		fprintf(stdout, "Failed to unload bpf_testmod.ko from kernel: %d\n", -errno);
> >  		return;
> >  	}
> >  	if (verbose)
> > @@ -270,11 +270,11 @@ int load_bpf_testmod(bool verbose)
> >  
> >  	fd = open("bpf_testmod.ko", O_RDONLY);
> >  	if (fd < 0) {
> > -		fprintf(stderr, "Can't find bpf_testmod.ko kernel module: %d\n", -errno);
> > +		fprintf(stdout, "Can't find bpf_testmod.ko kernel module: %d\n", -errno);
> >  		return -ENOENT;
> >  	}
> >  	if (finit_module(fd, "", 0)) {
> > -		fprintf(stderr, "Failed to load bpf_testmod.ko into the kernel: %d\n", -errno);
> > +		fprintf(stdout, "Failed to load bpf_testmod.ko into the kernel: %d\n", -errno);
> >  		close(fd);
> >  		return -EINVAL;
> >  	}
> > -- 
> > 2.39.1
> >