2021-11-01 12:38:19

by Yang Yingliang

[permalink] [raw]
Subject: [PATCH -next v2] bpf/benchs: Fix return value check of bpf_program__attach()

If bpf_program__attach() fails, it never returns NULL,
we should use libbpf_get_error() to check the return value.

Reported-by: Hulk Robot <[email protected]>
Signed-off-by: Yang Yingliang <[email protected]>
Acked-by: Yonghong Song <[email protected]>
---
v2:
don't use 'int err'
---
.../selftests/bpf/benchs/bench_bloom_filter_map.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
index 6eeeed2913e6..4afaa4adb327 100644
--- a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
+++ b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
@@ -304,7 +304,7 @@ static void bloom_lookup_setup(void)
populate_maps();

link = bpf_program__attach(ctx.skel->progs.bloom_lookup);
- if (!link) {
+ if (libbpf_get_error(link)) {
fprintf(stderr, "failed to attach program!\n");
exit(1);
}
@@ -321,7 +321,7 @@ static void bloom_update_setup(void)
populate_maps();

link = bpf_program__attach(ctx.skel->progs.bloom_update);
- if (!link) {
+ if (libbpf_get_error(link)) {
fprintf(stderr, "failed to attach program!\n");
exit(1);
}
@@ -340,7 +340,7 @@ static void false_positive_setup(void)
populate_maps();

link = bpf_program__attach(ctx.skel->progs.bloom_hashmap_lookup);
- if (!link) {
+ if (libbpf_get_error(link)) {
fprintf(stderr, "failed to attach program!\n");
exit(1);
}
@@ -358,7 +358,7 @@ static void hashmap_with_bloom_setup(void)
populate_maps();

link = bpf_program__attach(ctx.skel->progs.bloom_hashmap_lookup);
- if (!link) {
+ if (libbpf_get_error(link)) {
fprintf(stderr, "failed to attach program!\n");
exit(1);
}
@@ -375,7 +375,7 @@ static void hashmap_no_bloom_setup(void)
populate_maps();

link = bpf_program__attach(ctx.skel->progs.bloom_hashmap_lookup);
- if (!link) {
+ if (libbpf_get_error(link)) {
fprintf(stderr, "failed to attach program!\n");
exit(1);
}
--
2.25.1


2021-11-01 22:02:34

by Alexei Starovoitov

[permalink] [raw]
Subject: Re: [PATCH -next v2] bpf/benchs: Fix return value check of bpf_program__attach()

On Mon, Nov 1, 2021 at 5:35 AM Yang Yingliang <[email protected]> wrote:
>
> If bpf_program__attach() fails, it never returns NULL,
> we should use libbpf_get_error() to check the return value.
>
> Reported-by: Hulk Robot <[email protected]>
> Signed-off-by: Yang Yingliang <[email protected]>
> Acked-by: Yonghong Song <[email protected]>
> ---
> v2:
> don't use 'int err'
> ---
> .../selftests/bpf/benchs/bench_bloom_filter_map.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> index 6eeeed2913e6..4afaa4adb327 100644
> --- a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> +++ b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> @@ -304,7 +304,7 @@ static void bloom_lookup_setup(void)
> populate_maps();
>
> link = bpf_program__attach(ctx.skel->progs.bloom_lookup);
> - if (!link) {
> + if (libbpf_get_error(link)) {

Please use ASSERT_OK_PTR() instead.
See how other tests are doing it.

2021-11-01 22:22:58

by Yonghong Song

[permalink] [raw]
Subject: Re: [PATCH -next v2] bpf/benchs: Fix return value check of bpf_program__attach()



On 11/1/21 3:00 PM, Alexei Starovoitov wrote:
> On Mon, Nov 1, 2021 at 5:35 AM Yang Yingliang <[email protected]> wrote:
>>
>> If bpf_program__attach() fails, it never returns NULL,
>> we should use libbpf_get_error() to check the return value.
>>
>> Reported-by: Hulk Robot <[email protected]>
>> Signed-off-by: Yang Yingliang <[email protected]>
>> Acked-by: Yonghong Song <[email protected]>
>> ---
>> v2:
>> don't use 'int err'
>> ---
>> .../selftests/bpf/benchs/bench_bloom_filter_map.c | 10 +++++-----
>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
>> index 6eeeed2913e6..4afaa4adb327 100644
>> --- a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
>> +++ b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
>> @@ -304,7 +304,7 @@ static void bloom_lookup_setup(void)
>> populate_maps();
>>
>> link = bpf_program__attach(ctx.skel->progs.bloom_lookup);
>> - if (!link) {
>> + if (libbpf_get_error(link)) {
>
> Please use ASSERT_OK_PTR() instead.
> See how other tests are doing it.

I actually looked at this. ASSERT_OK_PTR() is defined in test_progs.h
and test_progs.h is ONLY included in files which eventually linked to
test_progs. That is why I didn't recommend to use ASSERT_OK_PTR().

Maybe it is okay to include test_progs.h in benchs/*.c. Or we may
want to refactor to a separate header file to contain these macros
which can be used for test_progs.h and other applications.

>

2021-11-01 22:33:22

by Alexei Starovoitov

[permalink] [raw]
Subject: Re: [PATCH -next v2] bpf/benchs: Fix return value check of bpf_program__attach()

On Mon, Nov 1, 2021 at 3:21 PM Yonghong Song <[email protected]> wrote:
>
>
>
> On 11/1/21 3:00 PM, Alexei Starovoitov wrote:
> > On Mon, Nov 1, 2021 at 5:35 AM Yang Yingliang <[email protected]> wrote:
> >>
> >> If bpf_program__attach() fails, it never returns NULL,
> >> we should use libbpf_get_error() to check the return value.
> >>
> >> Reported-by: Hulk Robot <[email protected]>
> >> Signed-off-by: Yang Yingliang <[email protected]>
> >> Acked-by: Yonghong Song <[email protected]>
> >> ---
> >> v2:
> >> don't use 'int err'
> >> ---
> >> .../selftests/bpf/benchs/bench_bloom_filter_map.c | 10 +++++-----
> >> 1 file changed, 5 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> >> index 6eeeed2913e6..4afaa4adb327 100644
> >> --- a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> >> +++ b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> >> @@ -304,7 +304,7 @@ static void bloom_lookup_setup(void)
> >> populate_maps();
> >>
> >> link = bpf_program__attach(ctx.skel->progs.bloom_lookup);
> >> - if (!link) {
> >> + if (libbpf_get_error(link)) {
> >
> > Please use ASSERT_OK_PTR() instead.
> > See how other tests are doing it.
>
> I actually looked at this. ASSERT_OK_PTR() is defined in test_progs.h
> and test_progs.h is ONLY included in files which eventually linked to
> test_progs. That is why I didn't recommend to use ASSERT_OK_PTR().
>
> Maybe it is okay to include test_progs.h in benchs/*.c. Or we may
> want to refactor to a separate header file to contain these macros
> which can be used for test_progs.h and other applications.

hmm.
Looks like bench_ringbufs.c has the same issue doing:
if (!link)
and bench_rename.c too.

Probably would be good to fix in all bench-s.

If test_progs.h cannot be included directly
copy-pasting ASSERT_OK_PTR in a reduced form into bench.h
is probably cleaner than open coding libbpf_get_error.

2021-11-02 02:49:04

by Andrii Nakryiko

[permalink] [raw]
Subject: Re: [PATCH -next v2] bpf/benchs: Fix return value check of bpf_program__attach()

On Mon, Nov 1, 2021 at 3:30 PM Alexei Starovoitov
<[email protected]> wrote:
>
> On Mon, Nov 1, 2021 at 3:21 PM Yonghong Song <[email protected]> wrote:
> >
> >
> >
> > On 11/1/21 3:00 PM, Alexei Starovoitov wrote:
> > > On Mon, Nov 1, 2021 at 5:35 AM Yang Yingliang <[email protected]> wrote:
> > >>
> > >> If bpf_program__attach() fails, it never returns NULL,
> > >> we should use libbpf_get_error() to check the return value.
> > >>
> > >> Reported-by: Hulk Robot <[email protected]>
> > >> Signed-off-by: Yang Yingliang <[email protected]>
> > >> Acked-by: Yonghong Song <[email protected]>
> > >> ---
> > >> v2:
> > >> don't use 'int err'
> > >> ---
> > >> .../selftests/bpf/benchs/bench_bloom_filter_map.c | 10 +++++-----
> > >> 1 file changed, 5 insertions(+), 5 deletions(-)
> > >>
> > >> diff --git a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> > >> index 6eeeed2913e6..4afaa4adb327 100644
> > >> --- a/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> > >> +++ b/tools/testing/selftests/bpf/benchs/bench_bloom_filter_map.c
> > >> @@ -304,7 +304,7 @@ static void bloom_lookup_setup(void)
> > >> populate_maps();
> > >>
> > >> link = bpf_program__attach(ctx.skel->progs.bloom_lookup);
> > >> - if (!link) {
> > >> + if (libbpf_get_error(link)) {
> > >
> > > Please use ASSERT_OK_PTR() instead.
> > > See how other tests are doing it.
> >
> > I actually looked at this. ASSERT_OK_PTR() is defined in test_progs.h
> > and test_progs.h is ONLY included in files which eventually linked to
> > test_progs. That is why I didn't recommend to use ASSERT_OK_PTR().
> >
> > Maybe it is okay to include test_progs.h in benchs/*.c. Or we may
> > want to refactor to a separate header file to contain these macros
> > which can be used for test_progs.h and other applications.
>
> hmm.
> Looks like bench_ringbufs.c has the same issue doing:
> if (!link)
> and bench_rename.c too.

bench.c does:

libbpf_set_strict_mode(LIBBPF_STRICT_ALL);

and so on error all the pointers will be NULL. So it's ok to check if
(!link) and not use libbpf_get_error() at all.

>
> Probably would be good to fix in all bench-s.
>
> If test_progs.h cannot be included directly
> copy-pasting ASSERT_OK_PTR in a reduced form into bench.h
> is probably cleaner than open coding libbpf_get_error.