On Tue, Mar 24, 2026 at 12:49:49PM +0800, Sun Jian wrote: > trampoline_count fills all trampoline attachment slots for a single > target function and verifies that one extra attach fails with -E2BIG. > > It currently targets bpf_modify_return_test, which is also used by > other selftests such as modify_return, get_func_ip_test, and > get_func_args_test. When such tests run in parallel, they can contend > for the same per-function trampoline quota and cause unexpected attach > failures. This issue is currently masked by harness serialization. > > Move trampoline_count to a dedicated bpf_testmod target and register it > for fmod_ret attachment. Also route the final trigger through > trigger_module_test_read(), so the execution path exercises the same > dedicated target. > > This keeps the test semantics unchanged while isolating it from other > selftests, so it no longer needs to run in serial mode. Remove the > TODO comment as well. > > Tested: > ./test_progs -t trampoline_count -vv > ./test_progs -j$(nproc) -t trampoline_count -vv > ./test_progs -j$(nproc) -t \ > trampoline_count,modify_return,get_func_ip_test,get_func_args_test -vv > 20 runs of: > ./test_progs -j$(nproc) -t \ > trampoline_count,modify_return,get_func_ip_test,get_func_args_test > > Signed-off-by: Sun Jian <[email protected]>
Acked-by: Jiri Olsa <[email protected]> jirka > --- > > Link: > https://lore.kernel.org/bpf/[email protected]/ > > v4: > - simplify the dedicated trampoline_count target and its trigger path > - simplify the associated fentry/fmod_ret/fexit test program signatures > - reduce the final trigger to a plain ASSERT_OK() > - drop Suggested-by per Jiri > > v3: > - route the final trigger through trigger_module_test_read() and make > bpf_testmod_test_read() call the dedicated trampoline_count target > > v2: > - rewrite the subject to describe the change > - resend with the correct patch content > > .../bpf/prog_tests/trampoline_count.c | 17 +++-------------- > .../bpf/progs/test_trampoline_count.c | 12 ++++++------ > .../selftests/bpf/test_kmods/bpf_testmod.c | 18 ++++++++++++++++++ > 3 files changed, 27 insertions(+), 20 deletions(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c > b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c > index 6cd7349d4a2b..7321850db75f 100644 > --- a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c > +++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c > @@ -30,16 +30,14 @@ static struct bpf_program *load_prog(char *file, char > *name, struct inst *inst) > return prog; > } > > -/* TODO: use different target function to run in concurrent mode */ > -void serial_test_trampoline_count(void) > +void test_trampoline_count(void) > { > char *file = "test_trampoline_count.bpf.o"; > char *const progs[] = { "fentry_test", "fmod_ret_test", "fexit_test" }; > - int bpf_max_tramp_links, err, i, prog_fd; > + int bpf_max_tramp_links, i; > struct bpf_program *prog; > struct bpf_link *link; > struct inst *inst; > - LIBBPF_OPTS(bpf_test_run_opts, opts); > > bpf_max_tramp_links = get_bpf_max_tramp_links(); > if (!ASSERT_GE(bpf_max_tramp_links, 1, "bpf_max_tramp_links")) > @@ -80,16 +78,7 @@ void serial_test_trampoline_count(void) > goto cleanup; > > /* and finally execute the probe */ > - prog_fd = bpf_program__fd(prog); > - if (!ASSERT_GE(prog_fd, 0, "bpf_program__fd")) > - goto cleanup; > - > - err = bpf_prog_test_run_opts(prog_fd, &opts); > - if (!ASSERT_OK(err, "bpf_prog_test_run_opts")) > - goto cleanup; > - > - ASSERT_EQ(opts.retval & 0xffff, 33, "bpf_modify_return_test.result"); > - ASSERT_EQ(opts.retval >> 16, 2, "bpf_modify_return_test.side_effect"); > + ASSERT_OK(trigger_module_test_read(256), "trigger_module_test_read"); > > cleanup: > for (; i >= 0; i--) { > diff --git a/tools/testing/selftests/bpf/progs/test_trampoline_count.c > b/tools/testing/selftests/bpf/progs/test_trampoline_count.c > index 7765720da7d5..02f52806b1b2 100644 > --- a/tools/testing/selftests/bpf/progs/test_trampoline_count.c > +++ b/tools/testing/selftests/bpf/progs/test_trampoline_count.c > @@ -3,20 +3,20 @@ > #include <bpf/bpf_helpers.h> > #include <bpf/bpf_tracing.h> > > -SEC("fentry/bpf_modify_return_test") > -int BPF_PROG(fentry_test, int a, int *b) > +SEC("fentry/bpf_testmod_trampoline_count_test") > +int BPF_PROG(fentry_test) > { > return 0; > } > > -SEC("fmod_ret/bpf_modify_return_test") > -int BPF_PROG(fmod_ret_test, int a, int *b, int ret) > +SEC("fmod_ret/bpf_testmod_trampoline_count_test") > +int BPF_PROG(fmod_ret_test, int ret) > { > return 0; > } > > -SEC("fexit/bpf_modify_return_test") > -int BPF_PROG(fexit_test, int a, int *b, int ret) > +SEC("fexit/bpf_testmod_trampoline_count_test") > +int BPF_PROG(fexit_test, int ret) > { > return 0; > } > diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c > b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c > index e62c6b78657f..9caf9ffa1bb0 100644 > --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c > +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c > @@ -470,6 +470,11 @@ noinline void bpf_testmod_stacktrace_test_1(void) > > int bpf_testmod_fentry_ok; > > +noinline int bpf_testmod_trampoline_count_test(void) > +{ > + return 0; > +} > + > noinline ssize_t > bpf_testmod_test_read(struct file *file, struct kobject *kobj, > const struct bin_attribute *bin_attr, > @@ -548,6 +553,8 @@ bpf_testmod_test_read(struct file *file, struct kobject > *kobj, > 21, 22, 23, 24, 25, 26) != 231) > goto out; > > + bpf_testmod_trampoline_count_test(); > + > bpf_testmod_stacktrace_test_1(); > > bpf_testmod_fentry_ok = 1; > @@ -1843,6 +1850,16 @@ struct bpf_struct_ops testmod_multi_st_ops = { > > extern int bpf_fentry_test1(int a); > > +BTF_KFUNCS_START(bpf_testmod_trampoline_count_ids) > +BTF_ID_FLAGS(func, bpf_testmod_trampoline_count_test) > +BTF_KFUNCS_END(bpf_testmod_trampoline_count_ids) > + > +static const struct > +btf_kfunc_id_set bpf_testmod_trampoline_count_fmodret_set = { > + .owner = THIS_MODULE, > + .set = &bpf_testmod_trampoline_count_ids, > +}; > + > static int bpf_testmod_init(void) > { > const struct btf_id_dtor_kfunc bpf_testmod_dtors[] = { > @@ -1859,6 +1876,7 @@ static int bpf_testmod_init(void) > ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, > &bpf_testmod_kfunc_set); > ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, > &bpf_testmod_kfunc_set); > ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, > &bpf_testmod_kfunc_set); > + ret = ret ?: > register_btf_fmodret_id_set(&bpf_testmod_trampoline_count_fmodret_set); > ret = ret ?: register_bpf_struct_ops(&bpf_bpf_testmod_ops, > bpf_testmod_ops); > ret = ret ?: register_bpf_struct_ops(&bpf_testmod_ops2, > bpf_testmod_ops2); > ret = ret ?: register_bpf_struct_ops(&bpf_testmod_ops3, > bpf_testmod_ops3); > > base-commit: 8a30aeb0d1b4e4aaf7f7bae72f20f2ae75385ccb > -- > 2.43.0 >
