Subject: Re: [PATCH bpf-next 5/7] selftests/bpf: switch test to new attach_perf_event API

From: Stanislav Fomichev <[email-masked]>
Date: Thu, 20 Jun 2019 17:08:19 -0700

On 06/20, Andrii Nakryiko wrote:
> Use new bpf_program__attach_perf_event() in test previously relying on
> direct ioctl manipulations.
Maybe use new detach/disable routine at the end of the
test_stacktrace_build_id_nmi as well?

> Signed-off-by: Andrii Nakryiko <[email-masked]>
> ---
>  .../bpf/prog_tests/stacktrace_build_id_nmi.c     | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
> index 1c1a2f75f3d8..1bbdb0b82ac5 100644
> --- a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
> +++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
> @@ -17,6 +17,7 @@ static __u64 read_perf_max_sample_freq(void)
>  void test_stacktrace_build_id_nmi(void)
>  {
>  	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
> +	const char *prog_name = "tracepoint/random/urandom_read";
>  	const char *file = "./test_stacktrace_build_id.o";
>  	int err, pmu_fd, prog_fd;
>  	struct perf_event_attr attr = {
> @@ -25,6 +26,7 @@ void test_stacktrace_build_id_nmi(void)
>  		.config = PERF_COUNT_HW_CPU_CYCLES,
>  	};
>  	__u32 key, previous_key, val, duration = 0;
> +	struct bpf_program *prog;
>  	struct bpf_object *obj;
>  	char buf[256];
>  	int i, j;
> @@ -39,6 +41,10 @@ void test_stacktrace_build_id_nmi(void)
>  	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
>  		return;
>  
> +	prog = bpf_object__find_program_by_title(obj, prog_name);
> +	if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
> +		goto close_prog;
> +
>  	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
>  			 0 /* cpu 0 */, -1 /* group id */,
>  			 0 /* flags */);
> @@ -47,16 +53,10 @@ void test_stacktrace_build_id_nmi(void)
>  		  pmu_fd, errno))
>  		goto close_prog;
>  
> -	err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
> -	if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",
> -		  err, errno))
> +	err = bpf_program__attach_perf_event(prog, pmu_fd);
> +	if (CHECK(err, "attach_perf_event", "err %d\n", err))
>  		goto close_pmu;
>  
> -	err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> -	if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",
> -		  err, errno))
> -		goto disable_pmu;
> -
>  	/* find map fds */
>  	control_map_fd = bpf_find_map(__func__, obj, "control_map");
>  	if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
> -- 
> 2.17.1
>