selftests/sched_ext: Fix flaky ddsp failure tests on busy systems

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The ddsp_vtimelocal_fail and ddsp_bogus_dsq_fail tests skip calling
scx_bpf_dsq_insert_vtime() if scx_bpf_pick_idle_cpu() fails to find an idle
CPU (returns a negative error code). On loaded systems, this results in the
tests skipping the very assertions they are meant to verify.

Eliminate this flakiness by falling back to prev_cpu if no idle CPU is
found, ensuring the illegal dispatch operations are unconditionally
attempted and tested.

Fixes: a5db7817af ("sched_ext: Add selftests")
Signed-off-by: Michal Blaszczyk <michalblk@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

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Michal Blaszczyk 2026-08-11 14:13:58 +00:00 • committed by Tejun Heo

parent 0e3a6e977c

commit e72979d326

2 changed files with 15 additions and 18 deletions

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20

tools/testing/selftests/sched_ext/ddsp_bogus_dsq_fail.bpf.c

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13

tools/testing/selftests/sched_ext/ddsp_vtimelocal_fail.bpf.c

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