selftests/resctrl: Make wraparound handling obvious

Within mba_setup() the programmed bandwidth delay value starts
at the maximum (100, or rather ALLOCATION_MAX) and progresses
towards ALLOCATION_MIN by decrementing with ALLOCATION_STEP.

The programmed bandwidth delay should never be negative, so
representing it with an unsigned int is most appropriate. This
may introduce confusion because of the "allocation > ALLOCATION_MAX"
check used to check wraparound of the subtraction.

Modify the mba_setup() flow to start at the minimum, ALLOCATION_MIN,
and incrementally, with ALLOCATION_STEP steps, adjust the
bandwidth delay value. This avoids wraparound while making the purpose
of "allocation > ALLOCATION_MAX" clear and eliminates the
need for the "allocation < ALLOCATION_MIN" check.

Reported-by: Ilpo Järvinen <[email protected]>
Closes: https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Reinette Chatre <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

0 files changed, 0 insertions, 0 deletions