linux-kernel - [PATCH] selftests/sched_ext: Fix exit selftest hang on UP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250701060845.134026-1-arighi@nvidia.com>
Date: Tue,  1 Jul 2025 08:08:45 +0200
From: Andrea Righi <arighi@...dia.com>
To: Tejun Heo <tj@...nel.org>,
	David Vernet <void@...ifault.com>,
	Changwoo Min <changwoo@...lia.com>
Cc: Phil Auld <pauld@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] selftests/sched_ext: Fix exit selftest hang on UP

On single-CPU systems, ops.select_cpu() is never called, causing the
EXIT_SELECT_CPU test case to wait indefinitely.

Avoid the stall by skipping this specific sub-test when only one CPU is
available.

Reported-by: Phil Auld <pauld@...hat.com>
Fixes: a5db7817af780 ("sched_ext: Add selftests")
Signed-off-by: Andrea Righi <arighi@...dia.com>
---
 tools/testing/selftests/sched_ext/exit.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/testing/selftests/sched_ext/exit.c b/tools/testing/selftests/sched_ext/exit.c
index 9451782689de1..ee25824b1cbe6 100644
--- a/tools/testing/selftests/sched_ext/exit.c
+++ b/tools/testing/selftests/sched_ext/exit.c
@@ -22,6 +22,14 @@ static enum scx_test_status run(void *ctx)
 		struct bpf_link *link;
 		char buf[16];
 
+		/*
+		 * On single-CPU systems, ops.select_cpu() is never
+		 * invoked, so skip this test to avoid getting stuck
+		 * indefinitely.
+		 */
+		if (tc == EXIT_SELECT_CPU && libbpf_num_possible_cpus() == 1)
+			continue;
+
 		skel = exit__open();
 		SCX_ENUM_INIT(skel);
 		skel->rodata->exit_point = tc;
-- 
2.50.0