enum size      : DAL_IRQ_SOURCES_NUMBER = 90
array extent   : irq_handler_list_{low,high}_tab[90] -> valid idx 0..89
accept src=89  (last valid) : true (correct)
accept src=90  (ONE PAST)   : true   <-- BUG: feeds tab[90] in
        amdgpu_dm_irq.c:238/:242/:123/:127 (list_add_tail/list walk)
accept src=91  (two past)   : false
accept src=0   (INVALID)    : false (correct)

RESULT: OFF-BY-ONE CONFIRMED - exactly index == array size passes
        the guard used by validate_irq_registration_params()
        and validate_irq_unregistration_params().
EXIT=0