* [PATCH] selftests/sched_ext: Fix exit selftest hang on UP
@ 2025-07-01 6:08 Andrea Righi
2025-07-01 13:00 ` Phil Auld
2025-07-03 16:45 ` Tejun Heo
0 siblings, 2 replies; 3+ messages in thread
From: Andrea Righi @ 2025-07-01 6:08 UTC (permalink / raw)
To: Tejun Heo, David Vernet, Changwoo Min; +Cc: Phil Auld, linux-kernel
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@redhat.com>
Fixes: a5db7817af780 ("sched_ext: Add selftests")
Signed-off-by: Andrea Righi <arighi@nvidia.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
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] selftests/sched_ext: Fix exit selftest hang on UP
2025-07-01 6:08 [PATCH] selftests/sched_ext: Fix exit selftest hang on UP Andrea Righi
@ 2025-07-01 13:00 ` Phil Auld
2025-07-03 16:45 ` Tejun Heo
1 sibling, 0 replies; 3+ messages in thread
From: Phil Auld @ 2025-07-01 13:00 UTC (permalink / raw)
To: Andrea Righi; +Cc: Tejun Heo, David Vernet, Changwoo Min, linux-kernel
On Tue, Jul 01, 2025 at 08:08:45AM +0200 Andrea Righi wrote:
> 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@redhat.com>
> Fixes: a5db7817af780 ("sched_ext: Add selftests")
> Signed-off-by: Andrea Righi <arighi@nvidia.com>
Thanks Andrea! You beat me to it. I didn't know that libbpf
call existed :)
Reviewed-by: Phil Auld <pauld@redhat.com>
and
Tested-by: Phil Auld <pauld@redhat.com>
Cheers,
Phil
> ---
> 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
>
--
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] selftests/sched_ext: Fix exit selftest hang on UP
2025-07-01 6:08 [PATCH] selftests/sched_ext: Fix exit selftest hang on UP Andrea Righi
2025-07-01 13:00 ` Phil Auld
@ 2025-07-03 16:45 ` Tejun Heo
1 sibling, 0 replies; 3+ messages in thread
From: Tejun Heo @ 2025-07-03 16:45 UTC (permalink / raw)
To: Andrea Righi; +Cc: David Vernet, Changwoo Min, Phil Auld, linux-kernel
On Tue, Jul 01, 2025 at 08:08:45AM +0200, Andrea Righi wrote:
> 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@redhat.com>
> Fixes: a5db7817af780 ("sched_ext: Add selftests")
> Signed-off-by: Andrea Righi <arighi@nvidia.com>
Applied to sched_ext/for-6.16-fixes.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-07-01 6:08 [PATCH] selftests/sched_ext: Fix exit selftest hang on UP Andrea Righi
2025-07-01 13:00 ` Phil Auld
2025-07-03 16:45 ` Tejun Heo
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