[PATCH] perf stat: Fix error check for bpf_program__attach

[Namhyung Kim]

It seems the bpf_program__attach() returns a negative error code
instead of a NULL pointer in case of error.

Fixes: 7fac83aaf2ee ("perf stat: Introduce 'bperf' to share hardware PMCs with BPF")
Cc: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/bpf_counter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index ddb52f748c8e..974f10e356f0 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -451,10 +451,10 @@ static int bperf_reload_leader_program(struct evsel *evsel, int attr_map_fd,
 		goto out;
 	}
 
-	err = -1;
 	link = bpf_program__attach(skel->progs.on_switch);
-	if (!link) {
+	if (IS_ERR(link)) {
 		pr_err("Failed to attach leader program\n");
+		err = PTR_ERR(link);
 		goto out;
 	}
 
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog