sched_ext: Make scx_bpf_dsq_insert*() return bool

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In preparation for hierarchical schedulers, change scx_bpf_dsq_insert() and
scx_bpf_dsq_insert_vtime() to return bool instead of void. With
sub-schedulers, there will be no reliable way to guarantee a task is still
owned by the sub-scheduler at insertion time (e.g., the task may have been
migrated to another scheduler). The bool return value will enable
sub-schedulers to detect and gracefully handle insertion failures.

For the root scheduler, insertion failures will continue to trigger scheduler
abort via scx_error(), so existing code doesn't need to check the return
value. Backward compatibility is maintained through compat wrappers.

Also update scx_bpf_dsq_move() documentation to clarify that it can return
false for sub-schedulers when @dsq_id points to a disallowed local DSQ.

Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

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This commit is contained in:

Tejun Heo 2025-10-06 15:51:47 -10:00

parent c0d630ba34

commit cded46d971

3 changed files with 56 additions and 15 deletions

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45

kernel/sched/ext.c

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3

tools/sched_ext/include/scx/common.bpf.h

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23

tools/sched_ext/include/scx/compat.bpf.h

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