selftests/bpf: Speed up module_attach test

The module_attach test contains subtests which check that unloading a
module while there are BPF programs attached to its functions is not
possible because the module is still referenced.

The problem is that the test calls the generic unload_module() helper
function which is used for module cleanup after test_progs terminate and
tries to wait until all module references are released. This
unnecessarily slows down the module_attach subtests since each
unsuccessful call to unload_module() takes about 1 second.

Introduce try_unload_module() which takes the number of retries as a
parameter. Make unload_module() call it with the currently used amount
of 10000 retries but call it with just 1 retry from module_attach tests
as it is always expected to fail. This speeds up the module_attach()
test significantly.

Before:

    # time ./test_progs -t module_attach
    [...]
    Summary: 1/14 PASSED, 0 SKIPPED, 0 FAILED

    real        0m5.011s
    user        0m0.293s
    sys         0m0.108s

After:

    # time ./test_progs -t module_attach
    [...]
    Summary: 1/14 PASSED, 0 SKIPPED, 0 FAILED

    real        0m0.350s
    user        0m0.197s
    sys         0m0.063s

Signed-off-by: Viktor Malik <vmalik@redhat.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260306101628.3822284-1-vmalik@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

3 files changed, 9 insertions, 3 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c
index 67763f609b6e..92c336333fcb 100644
--- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
@@ -151,7 +151,7 @@ static void test_module_attach_detach(const char *prog_name)
 	if (!ASSERT_OK_PTR(link, "module_attach attach"))
 		goto cleanup;
 
-	ASSERT_ERR(unload_bpf_testmod(false), "unload_bpf_testmod");
+	ASSERT_ERR(try_unload_module("bpf_testmod", 1, false), "try_unload_module");
 	bpf_link__destroy(link);
 cleanup:
 	test_module_attach__destroy(skel);
diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
index 66af0d13751a..6fbe1e995660 100644
--- a/tools/testing/selftests/bpf/testing_helpers.c
+++ b/tools/testing/selftests/bpf/testing_helpers.c
@@ -368,7 +368,7 @@ int delete_module(const char *name, int flags)
 	return syscall(__NR_delete_module, name, flags);
 }
 
-int unload_module(const char *name, bool verbose)
+int try_unload_module(const char *name, int retries, bool verbose)
 {
 	int ret, cnt = 0;
 
@@ -379,7 +379,7 @@ int unload_module(const char *name, bool verbose)
 		ret = delete_module(name, 0);
 		if (!ret || errno != EAGAIN)
 			break;
-		if (++cnt > 10000) {
+		if (++cnt > retries) {
 			fprintf(stdout, "Unload of %s timed out\n", name);
 			break;
 		}
@@ -400,6 +400,11 @@ int unload_module(const char *name, bool verbose)
 	return 0;
 }
 
+int unload_module(const char *name, bool verbose)
+{
+	return try_unload_module(name, 10000, verbose);
+}
+
 static int __load_module(const char *path, const char *param_values, bool verbose)
 {
 	int fd;
diff --git a/tools/testing/selftests/bpf/testing_helpers.h b/tools/testing/selftests/bpf/testing_helpers.h
index eb20d3772218..2ca2356a0b58 100644
--- a/tools/testing/selftests/bpf/testing_helpers.h
+++ b/tools/testing/selftests/bpf/testing_helpers.h
@@ -40,6 +40,7 @@ int finit_module(int fd, const char *param_values, int flags);
 int delete_module(const char *name, int flags);
 int load_module(const char *path, bool verbose);
 int load_module_params(const char *path, const char *param_values, bool verbose);
+int try_unload_module(const char *name, int retries, bool verbose);
 int unload_module(const char *name, bool verbose);
 
 static inline __u64 get_time_ns(void)