* [PATCH] selftests/bpf: trampoline_count: use dedicated target function
@ 2026-03-15 5:42 Sun Jian
2026-03-17 0:12 ` Paul Chaignon
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Sun Jian @ 2026-03-15 5:42 UTC (permalink / raw)
To: andrii, eddyz87, shuah
Cc: ast, daniel, martin.lau, song, yonghong.song, john.fastabend,
kpsingh, sdf, haoluo, jolsa, bpf, linux-kselftest, linux-kernel,
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
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
---
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] selftests/bpf: trampoline_count: use dedicated target function
2026-03-15 5:42 [PATCH] selftests/bpf: trampoline_count: use dedicated target function Sun Jian
@ 2026-03-17 0:12 ` Paul Chaignon
2026-03-17 1:02 ` [PATCH v2] " Sun Jian
2026-03-19 0:14 ` [PATCH] " Alexei Starovoitov
2 siblings, 0 replies; 6+ messages in thread
From: Paul Chaignon @ 2026-03-17 0:12 UTC (permalink / raw)
To: Sun Jian
Cc: andrii, eddyz87, shuah, ast, daniel, martin.lau, song,
yonghong.song, john.fastabend, kpsingh, sdf, haoluo, jolsa, bpf,
linux-kselftest, linux-kernel
On Sun, Mar 15, 2026 at 01:42:27PM +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
> 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
I was able to reproduce the issue here then validate the fix. I however
had to include several more tests that use bpf_modify_return_test
(get_func_args_test, kprobe_multi_test, missed, and bpf_cookie) before
I could reliably reproduce (in a loop that runs until it fails with
an unexpected E2BIG).
Tested-by: Paul Chaignon <paul.chaignon@gmail.com>
[...]
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] selftests/bpf: trampoline_count: use dedicated target function
2026-03-15 5:42 [PATCH] selftests/bpf: trampoline_count: use dedicated target function Sun Jian
2026-03-17 0:12 ` Paul Chaignon
@ 2026-03-17 1:02 ` Sun Jian
2026-03-17 10:54 ` Paul Chaignon
2026-03-19 0:14 ` [PATCH] " Alexei Starovoitov
2 siblings, 1 reply; 6+ 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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2] selftests/bpf: trampoline_count: use dedicated target function
2026-03-17 1:02 ` [PATCH v2] " Sun Jian
@ 2026-03-17 10:54 ` Paul Chaignon
0 siblings, 0 replies; 6+ messages in thread
From: Paul Chaignon @ 2026-03-17 10:54 UTC (permalink / raw)
To: Sun Jian
Cc: bpf, 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
On Tue, Mar 17, 2026 at 09:02:09AM +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
> 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
FYI, in general, unless there are merge conflicts, you don't need to
resend just for the tags. Maintainers can apply those when they merge.
[...]
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] selftests/bpf: trampoline_count: use dedicated target function
2026-03-15 5:42 [PATCH] selftests/bpf: trampoline_count: use dedicated target function Sun Jian
2026-03-17 0:12 ` Paul Chaignon
2026-03-17 1:02 ` [PATCH v2] " Sun Jian
@ 2026-03-19 0:14 ` Alexei Starovoitov
2 siblings, 0 replies; 6+ messages in thread
From: Alexei Starovoitov @ 2026-03-19 0:14 UTC (permalink / raw)
To: Sun Jian
Cc: Andrii Nakryiko, Eduard, Shuah Khan, Alexei Starovoitov,
Daniel Borkmann, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Stanislav Fomichev, Hao Luo, Jiri Olsa,
bpf, open list:KERNEL SELFTEST FRAMEWORK, LKML
On Sat, Mar 14, 2026 at 10:42 PM Sun Jian <sun.jian.kdev@gmail.com> 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
> 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
>
> Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
> ---
> 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;
> +}
No. We're not adding test code to the kernel anymore.
That's what test_kmod is for.
pw-bot: cr
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] selftests/bpf: trampoline_count: use dedicated target function
2026-03-19 3:12 [PATCH] selftests/bpf: trampoline_count: use dedicated bpf_testmod target Sun Jian
@ 2026-03-19 3:46 ` Sun Jian
0 siblings, 0 replies; 6+ messages in thread
From: Sun Jian @ 2026-03-19 3:46 UTC (permalink / raw)
To: ast, daniel, andrii, shuah
Cc: martin.lau, eddyz87, song, yonghong.song, john.fastabend, kpsingh,
sdf, haoluo, jolsa, paul.chaignon, bpf, linux-kselftest,
linux-kernel, 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
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-03-19 3:47 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-03-15 5:42 [PATCH] selftests/bpf: trampoline_count: use dedicated target function Sun Jian
2026-03-17 0:12 ` Paul Chaignon
2026-03-17 1:02 ` [PATCH v2] " Sun Jian
2026-03-17 10:54 ` Paul Chaignon
2026-03-19 0:14 ` [PATCH] " Alexei Starovoitov
-- strict thread matches above, loose matches on Subject: below --
2026-03-19 3:12 [PATCH] selftests/bpf: trampoline_count: use dedicated bpf_testmod target Sun Jian
2026-03-19 3:46 ` [PATCH v2] selftests/bpf: trampoline_count: use dedicated target function Sun Jian
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