SOFTIRQ_BITS       39 include/linux/preempt.h #define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
SOFTIRQ_BITS       45 include/linux/preempt.h #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)