static void blk_iopoll_softirq(struct softirq_action *h)
{
	struct list_head *list = &__get_cpu_var(blk_cpu_iopoll);
	int rearm = 0, budget = blk_iopoll_budget;
	unsigned long start_time = jiffies;

	local_irq_disable();

	while (!list_empty(list)) {
		struct blk_iopoll *iop;
		int work, weight;

		/*
		 * If softirq window is exhausted then punt.
		 */
		if (budget <= 0 || time_after(jiffies, start_time)) {
			rearm = 1;
			break;
		}

		local_irq_enable();

		/* Even though interrupts have been re-enabled, this
		 * access is safe because interrupts can only add new
		 * entries to the tail of this list, and only ->poll()
		 * calls can remove this head entry from the list.
		 */
		iop = list_entry(list->next, struct blk_iopoll, list);

		weight = iop->weight;
		work = 0;
		if (test_bit(IOPOLL_F_SCHED, &iop->state))
			work = iop->poll(iop, weight);

		budget -= work;

		local_irq_disable();

		/*
		 * Drivers must not modify the iopoll state, if they
		 * consume their assigned weight (or more, some drivers can't
		 * easily just stop processing, they have to complete an
		 * entire mask of commands).In such cases this code
		 * still "owns" the iopoll instance and therefore can
		 * move the instance around on the list at-will.
		 */
		if (work >= weight) {
			if (blk_iopoll_disable_pending(iop))
				__blk_iopoll_complete(iop);
			else
				list_move_tail(&iop->list, list);
		}
	}

	if (rearm)
		__raise_softirq_irqoff(BLOCK_IOPOLL_SOFTIRQ);

	local_irq_enable();
	preempt_check_resched_rt();
}
Beispiel #2
0
/**
 * blk_iopoll_complete - Mark this @iop as un-polled again
 * @iop:      The parent iopoll structure
 *
 * Description:
 *     If a driver consumes less than the assigned budget in its run of the
 *     iopoll handler, it'll end the polled mode by calling this function. The
 *     iopoll handler will not be invoked again before blk_iopoll_sched_prep()
 *     is called.
 **/
void blk_iopoll_complete(struct blk_iopoll *iopoll)
{
	unsigned long flags;

	local_irq_save(flags);
	__blk_iopoll_complete(iopoll);
	local_irq_restore(flags);
}