On 2026/1/22 08:07 Andrii Nakryiko [off-list ref] write:

On Thu, Jan 15, 2026 at 3:24 AM Menglong Dong [off-list ref] wrote:

quoted

Test session cookie for fsession. Multiple fsession BPF progs is attached
to bpf_fentry_test1() and session cookie is read and write in the
testcase.

Signed-off-by: Menglong Dong <redacted>
---
v3:
- restructure the testcase by combine the testcases for session cookie and
  get_func_ip into one patch
---
 .../selftests/bpf/progs/fsession_test.c       | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/fsession_test.c b/tools/testing/selftests/bpf/progs/fsession_test.c
index f504984d42f2..4e55ca67db46 100644
--- a/tools/testing/selftests/bpf/progs/fsession_test.c
+++ b/tools/testing/selftests/bpf/progs/fsession_test.c

@@ -108,3 +108,56 @@ int BPF_PROG(test6, int a)
                test6_entry_result = (const void *) addr == &bpf_fentry_test1;
        return 0;
 }
+
+__u64 test7_entry_ok = 0;
+__u64 test7_exit_ok = 0;
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test7, int a)
+{
+       __u64 *cookie = bpf_session_cookie(ctx);
+
+       if (!bpf_session_is_return(ctx)) {
+               *cookie = 0xAAAABBBBCCCCDDDDull;
+               test7_entry_ok = *cookie == 0xAAAABBBBCCCCDDDDull;

you are trying to double-check that writing into *cookie preserves the
written value, is that right? Do we need volatile read here to ensure
that compiler doesn't optimize this?

Yeah, you are right. READ_ONCE and WRITE_ONCE should be used
here. I'll use them next version.

Thanks!
Menglong Dong

quoted

+               return 0;
+       }
+
+       test7_exit_ok = *cookie == 0xAAAABBBBCCCCDDDDull;
+       return 0;
+}
+
+__u64 test8_entry_ok = 0;
+__u64 test8_exit_ok = 0;
+
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test8, int a)
+{
+       __u64 *cookie = bpf_session_cookie(ctx);
+
+       if (!bpf_session_is_return(ctx)) {
+               *cookie = 0x1111222233334444ull;
+               test8_entry_ok = *cookie == 0x1111222233334444ull;
+               return 0;
+       }
+
+       test8_exit_ok = *cookie == 0x1111222233334444ull;
+       return 0;
+}
+
+__u64 test9_entry_result = 0;
+__u64 test9_exit_result = 0;
+
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test9, int a, int ret)
+{
+       __u64 *cookie = bpf_session_cookie(ctx);
+
+       if (!bpf_session_is_return(ctx)) {
+               test9_entry_result = a == 1 && ret == 0;
+               *cookie = 0x123456ULL;
+               return 0;
+       }
+
+       test9_exit_result = a == 1 && ret == 2 && *cookie == 0x123456ULL;
+       return 0;
+}
--
2.52.0