f596e2ce1c
When booting kernels built with both CONFIG_RCU_STRICT_GRACE_PERIOD=y and CONFIG_PREEMPT_RT=y, the rcu_read_unlock_special() function's invocation of irq_work_queue_on() the init_irq_work() causes the rcu_preempt_deferred_qs_handler() function to work execute in SCHED_FIFO irq_work kthreads. Because rcu_read_unlock_special() is invoked on each rcu_read_unlock() in such kernels, the amount of work just keeps piling up, resulting in a boot-time hang. This commit therefore avoids this hang by using IRQ_WORK_INIT_HARD() instead of init_irq_work(), but only in kernels built with both CONFIG_PREEMPT_RT=y and CONFIG_RCU_STRICT_GRACE_PERIOD=y. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>