selftests: Remove fmod_ret from test_overhead

The test_overhead prog_test included an fmod_ret program that attached to
__set_task_comm() in the kernel. However, this function was never listed as
allowed for return modification, so this only worked because of the
verifier skipping tests when a trampoline already existed for the attach
point. Now that the verifier checks have been fixed, remove fmod_ret from
the test so it works again.

Fixes: 4eaf0b5 ("selftest/bpf: Fmod_ret prog and implement test_overhead as part of bench")
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Author: tohojo

tools/testing/selftests/bpf/bench.c

@@ -311,7 +311,6 @@ extern const struct bench bench_rename_kretprobe;
 extern const struct bench bench_rename_rawtp;
 extern const struct bench bench_rename_fentry;
 extern const struct bench bench_rename_fexit;
-extern const struct bench bench_rename_fmodret;
 extern const struct bench bench_trig_base;
 extern const struct bench bench_trig_tp;
 extern const struct bench bench_trig_rawtp;
@@ -333,7 +332,6 @@ static const struct bench *benchs[] = {
 	&bench_rename_rawtp,
 	&bench_rename_fentry,
 	&bench_rename_fexit,
-	&bench_rename_fmodret,
 	&bench_trig_base,
 	&bench_trig_tp,
 	&bench_trig_rawtp,
@@ -464,4 +462,3 @@ int main(int argc, char **argv)
 
 	return 0;
 }
-

tools/testing/selftests/bpf/benchs/bench_rename.c

@@ -106,12 +106,6 @@ static void setup_fexit()
 	attach_bpf(ctx.skel->progs.prog5);
 }
 
-static void setup_fmodret()
-{
-	setup_ctx();
-	attach_bpf(ctx.skel->progs.prog6);
-}
-
 static void *consumer(void *input)
 {
 	return NULL;
@@ -182,14 +176,3 @@ const struct bench bench_rename_fexit = {
 	.report_progress = hits_drops_report_progress,
 	.report_final = hits_drops_report_final,
 };
-
-const struct bench bench_rename_fmodret = {
-	.name = "rename-fmodret",
-	.validate = validate,
-	.setup = setup_fmodret,
-	.producer_thread = producer,
-	.consumer_thread = consumer,
-	.measure = measure,
-	.report_progress = hits_drops_report_progress,
-	.report_final = hits_drops_report_final,
-};

tools/testing/selftests/bpf/prog_tests/test_overhead.c

@@ -61,10 +61,9 @@ void test_test_overhead(void)
 	const char *raw_tp_name = "raw_tp/task_rename";
 	const char *fentry_name = "fentry/__set_task_comm";
 	const char *fexit_name = "fexit/__set_task_comm";
-	const char *fmodret_name = "fmod_ret/__set_task_comm";
 	const char *kprobe_func = "__set_task_comm";
 	struct bpf_program *kprobe_prog, *kretprobe_prog, *raw_tp_prog;
-	struct bpf_program *fentry_prog, *fexit_prog, *fmodret_prog;
+	struct bpf_program *fentry_prog, *fexit_prog;
 	struct bpf_object *obj;
 	struct bpf_link *link;
 	int err, duration = 0;
@@ -97,11 +96,6 @@ void test_test_overhead(void)
 	if (CHECK(!fexit_prog, "find_probe",
 		  "prog '%s' not found\n", fexit_name))
 		goto cleanup;
-	fmodret_prog = bpf_object__find_program_by_title(obj, fmodret_name);
-	if (CHECK(!fmodret_prog, "find_probe",
-		  "prog '%s' not found\n", fmodret_name))
-		goto cleanup;
-
 	err = bpf_object__load(obj);
 	if (CHECK(err, "obj_load", "err %d\n", err))
 		goto cleanup;
@@ -148,12 +142,6 @@ void test_test_overhead(void)
 	test_run("fexit");
 	bpf_link__destroy(link);
 
-	/* attach fmod_ret */
-	link = bpf_program__attach_trace(fmodret_prog);
-	if (CHECK(IS_ERR(link), "attach fmod_ret", "err %ld\n", PTR_ERR(link)))
-		goto cleanup;
-	test_run("fmod_ret");
-	bpf_link__destroy(link);
 cleanup:
 	prctl(PR_SET_NAME, comm, 0L, 0L, 0L);
 	bpf_object__close(obj);

tools/testing/selftests/bpf/progs/test_overhead.c

@@ -39,10 +39,4 @@ int BPF_PROG(prog5, struct task_struct *tsk, const char *buf, bool exec)
 	return 0;
 }
 
-SEC("fmod_ret/__set_task_comm")
-int BPF_PROG(prog6, struct task_struct *tsk, const char *buf, bool exec)
-{
-	return !tsk;
-}
-
 char _license[] SEC("license") = "GPL";