[PATCH] sched_ext/selftests: Fix bpf_link leak on assertion failure

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From: David Carlier <devnexen@gmail.com>
To: Tejun Heo <tj@kernel.org>, David Vernet <void@manifault.com>,
	Andrea Righi <arighi@nvidia.com>
Cc: linux-kernel@vger.kernel.org, David Carlier <devnexen@gmail.com>
Subject: [PATCH] sched_ext/selftests: Fix bpf_link leak on assertion failure
Date: Tue, 17 Mar 2026 17:44:02 +0000	[thread overview]
Message-ID: <20260317174402.48082-1-devnexen@gmail.com> (raw)

The SCX_EQ/SCX_ASSERT/SCX_FAIL_IF macros expand to return
SCX_TEST_FAIL on failure. When an assertion fires after
bpf_map__attach_struct_ops() but before bpf_link__destroy(), the
link leaks. Since the test runner is a single process, the leaked
link keeps the BPF scheduler attached, causing subsequent tests to
fail to attach their own scheduler -- cascading test failures from
a single bug.

Fix by moving bpf_link__destroy() before assertions. UEI and BSS
data live in the skeleton's mmap'd sections and survive link
destruction, following the existing pattern in dsp_local_on.c.

Signed-off-by: David Carlier <devnexen@gmail.com>
---
 tools/testing/selftests/sched_ext/ddsp_bogus_dsq_fail.c       | 2 +-
 tools/testing/selftests/sched_ext/ddsp_vtimelocal_fail.c      | 2 +-
 tools/testing/selftests/sched_ext/exit.c                      | 2 +-
 tools/testing/selftests/sched_ext/hotplug.c                   | 4 ++--
 tools/testing/selftests/sched_ext/numa.c                      | 2 +-
 tools/testing/selftests/sched_ext/prog_run.c                  | 4 ++--
 tools/testing/selftests/sched_ext/rt_stall.c                  | 2 +-
 .../testing/selftests/sched_ext/select_cpu_dispatch_bad_dsq.c | 2 +-
 .../testing/selftests/sched_ext/select_cpu_dispatch_dbl_dsp.c | 2 +-
 tools/testing/selftests/sched_ext/select_cpu_vtime.c          | 3 +--
 10 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/sched_ext/ddsp_bogus_dsq_fail.c b/tools/testing/selftests/sched_ext/ddsp_bogus_dsq_fail.c
index b6d13496b24e..c326c914f217 100644
--- a/tools/testing/selftests/sched_ext/ddsp_bogus_dsq_fail.c
+++ b/tools/testing/selftests/sched_ext/ddsp_bogus_dsq_fail.c
@@ -35,8 +35,8 @@ static enum scx_test_status run(void *ctx)
 
 	sleep(1);
 
-	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 	bpf_link__destroy(link);
+	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 
 	return SCX_TEST_PASS;
 }
diff --git a/tools/testing/selftests/sched_ext/ddsp_vtimelocal_fail.c b/tools/testing/selftests/sched_ext/ddsp_vtimelocal_fail.c
index af9ce4ee8baa..5142ff19a9c4 100644
--- a/tools/testing/selftests/sched_ext/ddsp_vtimelocal_fail.c
+++ b/tools/testing/selftests/sched_ext/ddsp_vtimelocal_fail.c
@@ -34,8 +34,8 @@ static enum scx_test_status run(void *ctx)
 
 	sleep(1);
 
-	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 	bpf_link__destroy(link);
+	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 
 	return SCX_TEST_PASS;
 }
diff --git a/tools/testing/selftests/sched_ext/exit.c b/tools/testing/selftests/sched_ext/exit.c
index b987611789d1..d9038e704ad4 100644
--- a/tools/testing/selftests/sched_ext/exit.c
+++ b/tools/testing/selftests/sched_ext/exit.c
@@ -45,11 +45,11 @@ static enum scx_test_status run(void *ctx)
 		while (skel->data->uei.kind == EXIT_KIND(SCX_EXIT_NONE))
 			sched_yield();
 
+		bpf_link__destroy(link);
 		SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_UNREG_BPF));
 		SCX_EQ(skel->data->uei.exit_code, tc);
 		sprintf(buf, "%d", tc);
 		SCX_ASSERT(!strcmp(skel->data->uei.msg, buf));
-		bpf_link__destroy(link);
 		exit__destroy(skel);
 	}
 
diff --git a/tools/testing/selftests/sched_ext/hotplug.c b/tools/testing/selftests/sched_ext/hotplug.c
index 0cfbb111a2d0..25aa60975fa3 100644
--- a/tools/testing/selftests/sched_ext/hotplug.c
+++ b/tools/testing/selftests/sched_ext/hotplug.c
@@ -84,13 +84,13 @@ static enum scx_test_status test_hotplug(bool onlining, bool cbs_defined)
 	while (!UEI_EXITED(skel, uei))
 		sched_yield();
 
+	bpf_link__destroy(link);
 	SCX_EQ(skel->data->uei.kind, kind);
 	SCX_EQ(UEI_REPORT(skel, uei), code);
 
 	if (!onlining)
 		toggle_online_status(1);
 
-	bpf_link__destroy(link);
 	hotplug__destroy(skel);
 
 	return SCX_TEST_PASS;
@@ -124,13 +124,13 @@ static enum scx_test_status test_hotplug_attach(void)
 	while (!UEI_EXITED(skel, uei))
 		sched_yield();
 
+	bpf_link__destroy(link);
 	kind = SCX_KIND_VAL(SCX_EXIT_UNREG_KERN);
 	code = SCX_ECODE_VAL(SCX_ECODE_ACT_RESTART) |
 	       SCX_ECODE_VAL(SCX_ECODE_RSN_HOTPLUG);
 	SCX_EQ(skel->data->uei.kind, kind);
 	SCX_EQ(UEI_REPORT(skel, uei), code);
 
-	bpf_link__destroy(link);
 	hotplug__destroy(skel);
 
 	return status;
diff --git a/tools/testing/selftests/sched_ext/numa.c b/tools/testing/selftests/sched_ext/numa.c
index b060c3b65c82..f1145be9cfa1 100644
--- a/tools/testing/selftests/sched_ext/numa.c
+++ b/tools/testing/selftests/sched_ext/numa.c
@@ -36,8 +36,8 @@ static enum scx_test_status run(void *ctx)
 	/* Just sleeping is fine, plenty of scheduling events happening */
 	sleep(1);
 
-	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_NONE));
 	bpf_link__destroy(link);
+	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_NONE));
 
 	return SCX_TEST_PASS;
 }
diff --git a/tools/testing/selftests/sched_ext/prog_run.c b/tools/testing/selftests/sched_ext/prog_run.c
index 05974820ca69..d101595b99b0 100644
--- a/tools/testing/selftests/sched_ext/prog_run.c
+++ b/tools/testing/selftests/sched_ext/prog_run.c
@@ -53,10 +53,10 @@ static enum scx_test_status run(void *ctx)
 	while (skel->data->uei.kind == EXIT_KIND(SCX_EXIT_NONE))
 		sched_yield();
 
-	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_UNREG_BPF));
-	SCX_EQ(skel->data->uei.exit_code, 0xdeadbeef);
 	close(prog_fd);
 	bpf_link__destroy(link);
+	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_UNREG_BPF));
+	SCX_EQ(skel->data->uei.exit_code, 0xdeadbeef);
 
 	return SCX_TEST_PASS;
 }
diff --git a/tools/testing/selftests/sched_ext/rt_stall.c b/tools/testing/selftests/sched_ext/rt_stall.c
index 81ea9b4883e5..a6bc5adbd930 100644
--- a/tools/testing/selftests/sched_ext/rt_stall.c
+++ b/tools/testing/selftests/sched_ext/rt_stall.c
@@ -260,8 +260,8 @@ static enum scx_test_status run(void *ctx)
 		}
 		res = sched_stress_test(is_ext);
 		if (is_ext) {
-			SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_NONE));
 			bpf_link__destroy(link);
+			SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_NONE));
 		}
 
 		if (!res)
diff --git a/tools/testing/selftests/sched_ext/select_cpu_dispatch_bad_dsq.c b/tools/testing/selftests/sched_ext/select_cpu_dispatch_bad_dsq.c
index 5e72ebbc90a5..db4369f509e7 100644
--- a/tools/testing/selftests/sched_ext/select_cpu_dispatch_bad_dsq.c
+++ b/tools/testing/selftests/sched_ext/select_cpu_dispatch_bad_dsq.c
@@ -35,8 +35,8 @@ static enum scx_test_status run(void *ctx)
 
 	sleep(1);
 
-	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 	bpf_link__destroy(link);
+	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 
 	return SCX_TEST_PASS;
 }
diff --git a/tools/testing/selftests/sched_ext/select_cpu_dispatch_dbl_dsp.c b/tools/testing/selftests/sched_ext/select_cpu_dispatch_dbl_dsp.c
index aa85949478bc..6c8a14b91327 100644
--- a/tools/testing/selftests/sched_ext/select_cpu_dispatch_dbl_dsp.c
+++ b/tools/testing/selftests/sched_ext/select_cpu_dispatch_dbl_dsp.c
@@ -35,8 +35,8 @@ static enum scx_test_status run(void *ctx)
 
 	sleep(1);
 
-	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 	bpf_link__destroy(link);
+	SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_ERROR));
 
 	return SCX_TEST_PASS;
 }
diff --git a/tools/testing/selftests/sched_ext/select_cpu_vtime.c b/tools/testing/selftests/sched_ext/select_cpu_vtime.c
index 1e9b5c9bfff1..7593aa05e03d 100644
--- a/tools/testing/selftests/sched_ext/select_cpu_vtime.c
+++ b/tools/testing/selftests/sched_ext/select_cpu_vtime.c
@@ -37,9 +37,8 @@ static enum scx_test_status run(void *ctx)
 
 	sleep(1);
 
-	SCX_ASSERT(skel->bss->consumed);
-
 	bpf_link__destroy(link);
+	SCX_ASSERT(skel->bss->consumed);
 
 	return SCX_TEST_PASS;
 }
-- 
2.53.0

next             reply	other threads:[~2026-03-17 17:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-17 17:44 David Carlier [this message]
2026-03-17 18:09 ` [PATCH] sched_ext/selftests: Fix bpf_link leak on assertion failure Tejun Heo
2026-03-17 18:28 ` [PATCH v2] " David Carlier

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