use libbpf_get_error() to check the return value of bpf_program__attach().
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Yu Kuai yukuai3@huawei.com --- tools/testing/selftests/bpf/benchs/bench_rename.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c index c7ec114eca56..b7d4a1d74fca 100644 --- a/tools/testing/selftests/bpf/benchs/bench_rename.c +++ b/tools/testing/selftests/bpf/benchs/bench_rename.c @@ -65,7 +65,7 @@ static void attach_bpf(struct bpf_program *prog) struct bpf_link *link;
link = bpf_program__attach(prog); - if (!link) { + if (libbpf_get_error(link)) { fprintf(stderr, "failed to attach program!\n"); exit(1); }
On 5/28/21 11:07 AM, Yu Kuai wrote:
use libbpf_get_error() to check the return value of bpf_program__attach().
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Yu Kuai yukuai3@huawei.com
tools/testing/selftests/bpf/benchs/bench_rename.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c index c7ec114eca56..b7d4a1d74fca 100644 --- a/tools/testing/selftests/bpf/benchs/bench_rename.c +++ b/tools/testing/selftests/bpf/benchs/bench_rename.c @@ -65,7 +65,7 @@ static void attach_bpf(struct bpf_program *prog) struct bpf_link *link; link = bpf_program__attach(prog);
- if (!link) {
- if (libbpf_get_error(link)) { fprintf(stderr, "failed to attach program!\n"); exit(1); }
Could you explain the rationale of this patch? bad2e478af3b ("selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks") explains: 'Fix all the explicit IS_ERR checks that now will be broken because libbpf returns NULL on error (and sets errno).' So the !link check looks totally reasonable to me. Converting to libbpf_get_error() is not wrong in itself, but given you don't make any use of the err code, there is also no point in this diff here.
Thanks, Daniel
On 2021/05/29 4:46, Daniel Borkmann wrote:
On 5/28/21 11:07 AM, Yu Kuai wrote:
use libbpf_get_error() to check the return value of bpf_program__attach().
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Yu Kuai yukuai3@huawei.com
tools/testing/selftests/bpf/benchs/bench_rename.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c index c7ec114eca56..b7d4a1d74fca 100644 --- a/tools/testing/selftests/bpf/benchs/bench_rename.c +++ b/tools/testing/selftests/bpf/benchs/bench_rename.c @@ -65,7 +65,7 @@ static void attach_bpf(struct bpf_program *prog) struct bpf_link *link; link = bpf_program__attach(prog); - if (!link) { + if (libbpf_get_error(link)) { fprintf(stderr, "failed to attach program!\n"); exit(1); }
Could you explain the rationale of this patch? bad2e478af3b ("selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks") explains: 'Fix all the explicit IS_ERR checks that now will be broken because libbpf returns NULL on error (and sets errno).' So the !link check looks totally reasonable to me. Converting to libbpf_get_error() is not wrong in itself, but given you don't make any use of the err code, there is also no point in this diff here.
Hi,
I was thinking that bpf_program__attach() can return error code theoretically(for example -ESRCH), and such case need to be handled.
Thanks, Yu Kuai
Thanks, Daniel .
On Fri, May 28, 2021 at 6:25 PM yukuai (C) yukuai3@huawei.com wrote:
On 2021/05/29 4:46, Daniel Borkmann wrote:
On 5/28/21 11:07 AM, Yu Kuai wrote:
use libbpf_get_error() to check the return value of bpf_program__attach().
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Yu Kuai yukuai3@huawei.com
tools/testing/selftests/bpf/benchs/bench_rename.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c index c7ec114eca56..b7d4a1d74fca 100644 --- a/tools/testing/selftests/bpf/benchs/bench_rename.c +++ b/tools/testing/selftests/bpf/benchs/bench_rename.c @@ -65,7 +65,7 @@ static void attach_bpf(struct bpf_program *prog) struct bpf_link *link; link = bpf_program__attach(prog);
- if (!link) {
- if (libbpf_get_error(link)) { fprintf(stderr, "failed to attach program!\n"); exit(1); }
Could you explain the rationale of this patch? bad2e478af3b ("selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks") explains: 'Fix all the explicit IS_ERR checks that now will be broken because libbpf returns NULL on error (and sets errno).' So the !link check looks totally reasonable to me. Converting to libbpf_get_error() is not wrong in itself, but given you don't make any use of the err code, there is also no point in this diff here.
Hi,
I was thinking that bpf_program__attach() can return error code theoretically(for example -ESRCH), and such case need to be handled.
I explicitly changed to NULL check + libbpf 1.0 error reporting mode because I don't care about specific error in benchmarks. So as Daniel and John pointed out, existing code is correct and doesn't need adjustment.
You are right, though, that error code is indeed returned, but you can check errno directly (but need to enable libbpf 1.0 mode) or use libbpf_get_error() (which will get deprecated some time before libbpf 1.0) if you don't know which mode your code will be run in.
Thanks, Yu Kuai
Thanks, Daniel .
Yu Kuai wrote:
use libbpf_get_error() to check the return value of bpf_program__attach().
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Yu Kuai yukuai3@huawei.com
tools/testing/selftests/bpf/benchs/bench_rename.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c index c7ec114eca56..b7d4a1d74fca 100644 --- a/tools/testing/selftests/bpf/benchs/bench_rename.c +++ b/tools/testing/selftests/bpf/benchs/bench_rename.c @@ -65,7 +65,7 @@ static void attach_bpf(struct bpf_program *prog) struct bpf_link *link; link = bpf_program__attach(prog);
- if (!link) {
- if (libbpf_get_error(link)) { fprintf(stderr, "failed to attach program!\n"); exit(1); }
--
Probably should be IS_ERR(link) same as the other benchs/*.c progs.
John Fastabend wrote:
Yu Kuai wrote:
use libbpf_get_error() to check the return value of bpf_program__attach().
Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Yu Kuai yukuai3@huawei.com
tools/testing/selftests/bpf/benchs/bench_rename.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c index c7ec114eca56..b7d4a1d74fca 100644 --- a/tools/testing/selftests/bpf/benchs/bench_rename.c +++ b/tools/testing/selftests/bpf/benchs/bench_rename.c @@ -65,7 +65,7 @@ static void attach_bpf(struct bpf_program *prog) struct bpf_link *link; link = bpf_program__attach(prog);
- if (!link) {
- if (libbpf_get_error(link)) { fprintf(stderr, "failed to attach program!\n"); exit(1); }
--
Probably should be IS_ERR(link) same as the other benchs/*.c progs.
Oops on wrong branch, agree with Daniel looks fine as !link otherwise need an explanation and fix the rest of the cases.
linux-kselftest-mirror@lists.linaro.org
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Andrii Nakryiko -
Daniel Borkmann -
John Fastabend -
Yu Kuai -
yukuai (C)