SOFTIRQ_BITS       32 include/linux/preempt_mask.h #define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
SOFTIRQ_BITS       38 include/linux/preempt_mask.h #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)