* [PATCH v2] selftests/bpf: trampoline_count: use dedicated target function
[not found] <20260315054227.118344-1-sun.jian.kdev@gmail.com>
@ 2026-03-17 1:02 ` Sun Jian
2026-03-17 10:54 ` Paul Chaignon
0 siblings, 1 reply; 2+ messages in thread
From: Sun Jian @ 2026-03-17 1:02 UTC (permalink / raw)
To: bpf
Cc: ast, daniel, andrii, martin.lau, eddyz87, song, yonghong.song,
john.fastabend, kpsingh, sdf, haoluo, jolsa, davem, edumazet,
kuba, pabeni, horms, shuah, netdev, linux-kernel, linux-kselftest,
paul.chaignon, Sun Jian
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
modify_return and get_func_ip_test. When those 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.
Add a dedicated bpf_trampoline_count_test target and switch
trampoline_count to use it. This keeps the test semantics unchanged
while isolating it from other modify_return-based 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 -t modify_return -vv
./test_progs -t get_func_ip_test -vv
./test_progs -j$(nproc) -t trampoline_count -vv
./test_progs -j$(nproc) -t
trampoline_count,modify_return,get_func_ip_test -vv
Tested-by: Paul Chaignon <paul.chaignon@gmail.com>
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
---
v2:
- add Paul's Tested-by
net/bpf/test_run.c | 7 +++++++
tools/testing/selftests/bpf/prog_tests/trampoline_count.c | 3 +--
tools/testing/selftests/bpf/progs/test_trampoline_count.c | 6 +++---
3 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 178c4738e63b..b41147a29f16 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -580,6 +580,12 @@ __bpf_kfunc int bpf_modify_return_test2(int a, int *b, short c, int d,
return a + *b + c + d + (long)e + f + g;
}
+__bpf_kfunc int bpf_trampoline_count_test(int a, int *b)
+{
+ *b += 1;
+ return a + *b;
+}
+
__bpf_kfunc int bpf_modify_return_test_tp(int nonce)
{
trace_bpf_trigger_tp(nonce);
@@ -635,6 +641,7 @@ BTF_KFUNCS_START(bpf_test_modify_return_ids)
BTF_ID_FLAGS(func, bpf_modify_return_test)
BTF_ID_FLAGS(func, bpf_modify_return_test2)
BTF_ID_FLAGS(func, bpf_modify_return_test_tp)
+BTF_ID_FLAGS(func, bpf_trampoline_count_test)
BTF_ID_FLAGS(func, bpf_fentry_test1, KF_SLEEPABLE)
BTF_KFUNCS_END(bpf_test_modify_return_ids)
diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
index 6cd7349d4a2b..b19358aed126 100644
--- a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
+++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
@@ -30,8 +30,7 @@ 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" };
diff --git a/tools/testing/selftests/bpf/progs/test_trampoline_count.c b/tools/testing/selftests/bpf/progs/test_trampoline_count.c
index 7765720da7d5..911d282fd423 100644
--- a/tools/testing/selftests/bpf/progs/test_trampoline_count.c
+++ b/tools/testing/selftests/bpf/progs/test_trampoline_count.c
@@ -3,19 +3,19 @@
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
-SEC("fentry/bpf_modify_return_test")
+SEC("fentry/bpf_trampoline_count_test")
int BPF_PROG(fentry_test, int a, int *b)
{
return 0;
}
-SEC("fmod_ret/bpf_modify_return_test")
+SEC("fmod_ret/bpf_trampoline_count_test")
int BPF_PROG(fmod_ret_test, int a, int *b, int ret)
{
return 0;
}
-SEC("fexit/bpf_modify_return_test")
+SEC("fexit/bpf_trampoline_count_test")
int BPF_PROG(fexit_test, int a, int *b, int ret)
{
return 0;
base-commit: 267594792a71018788af69e836c52e34bb8054af
--
2.43.0
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