[mirror_ubuntu-artful-kernel.git] / block / blk-softirq.c

/*
 * Functions related to softirq rq completions
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/cpu.h>

#include "blk.h"

static DEFINE_PER_CPU(struct list_head, blk_cpu_done);

/*
 * Softirq action handler - move entries to local list and loop over them
 * while passing them to the queue registered handler.
 */
static void blk_done_softirq(struct softirq_action *h)
{
	struct list_head *cpu_list, local_list;

	local_irq_disable();
	cpu_list = &__get_cpu_var(blk_cpu_done);
	list_replace_init(cpu_list, &local_list);
	local_irq_enable();

	while (!list_empty(&local_list)) {
		struct request *rq;

		rq = list_entry(local_list.next, struct request, csd.list);
		list_del_init(&rq->csd.list);
		rq->q->softirq_done_fn(rq);
	}
}

#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
static void trigger_softirq(void *data)
{
	struct request *rq = data;
	unsigned long flags;
	struct list_head *list;

	local_irq_save(flags);
	list = &__get_cpu_var(blk_cpu_done);
	list_add_tail(&rq->csd.list, list);

	if (list->next == &rq->csd.list)
		raise_softirq_irqoff(BLOCK_SOFTIRQ);

	local_irq_restore(flags);
}

/*
 * Setup and invoke a run of 'trigger_softirq' on the given cpu.
 */
static int raise_blk_irq(int cpu, struct request *rq)
{
	if (cpu_online(cpu)) {
		struct call_single_data *data = &rq->csd;

		data->func = trigger_softirq;
		data->info = rq;
		data->flags = 0;

		__smp_call_function_single(cpu, data, 0);
		return 0;
	}

	return 1;
}
#else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
static int raise_blk_irq(int cpu, struct request *rq)
{
	return 1;
}
#endif

static int __cpuinit blk_cpu_notify(struct notifier_block *self,
				    unsigned long action, void *hcpu)
{
	/*
	 * If a CPU goes away, splice its entries to the current CPU
	 * and trigger a run of the softirq
	 */
	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
		int cpu = (unsigned long) hcpu;

		local_irq_disable();
		list_splice_init(&per_cpu(blk_cpu_done, cpu),
				 &__get_cpu_var(blk_cpu_done));
		raise_softirq_irqoff(BLOCK_SOFTIRQ);
		local_irq_enable();
	}

	return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata blk_cpu_notifier = {
	.notifier_call	= blk_cpu_notify,
};

void __blk_complete_request(struct request *req)
{
	int ccpu, cpu;
	struct request_queue *q = req->q;
	unsigned long flags;

	BUG_ON(!q->softirq_done_fn);

	local_irq_save(flags);
	cpu = smp_processor_id();

	/*
	 * Select completion CPU
	 */
	if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) {
		ccpu = req->cpu;
		if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
			ccpu = blk_cpu_to_group(ccpu);
	} else
		ccpu = cpu;

	if (ccpu == cpu) {
		struct list_head *list;
do_local:
		list = &__get_cpu_var(blk_cpu_done);
		list_add_tail(&req->csd.list, list);

		/*
		 * if the list only contains our just added request,
		 * signal a raise of the softirq. If there are already
		 * entries there, someone already raised the irq but it
		 * hasn't run yet.
		 */
		if (list->next == &req->csd.list)
			raise_softirq_irqoff(BLOCK_SOFTIRQ);
	} else if (raise_blk_irq(ccpu, req))
		goto do_local;

	local_irq_restore(flags);
}

/**
 * blk_complete_request - end I/O on a request
 * @req:      the request being processed
 *
 * Description:
 *     Ends all I/O on a request. It does not handle partial completions,
 *     unless the driver actually implements this in its completion callback
 *     through requeueing. The actual completion happens out-of-order,
 *     through a softirq handler. The user must have registered a completion
 *     callback through blk_queue_softirq_done().
 **/
void blk_complete_request(struct request *req)
{
	if (unlikely(blk_should_fake_timeout(req->q)))
		return;
	if (!blk_mark_rq_complete(req))
		__blk_complete_request(req);
}
EXPORT_SYMBOL(blk_complete_request);

static __init int blk_softirq_init(void)
{
	int i;

	for_each_possible_cpu(i)
		INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));

	open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
	register_hotcpu_notifier(&blk_cpu_notifier);
	return 0;
}
subsys_initcall(blk_softirq_init);
Commit	Line	Data
b646fc59 JA	1	/*
	2	* Functions related to softirq rq completions
	3	*/
	4	#include <linux/kernel.h>
	5	#include <linux/module.h>
	6	#include <linux/init.h>
	7	#include <linux/bio.h>
	8	#include <linux/blkdev.h>
	9	#include <linux/interrupt.h>
	10	#include <linux/cpu.h>
	11
	12	#include "blk.h"
	13
	14	static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
	15
c7c22e4d JA	16	/*
	17	* Softirq action handler - move entries to local list and loop over them
	18	* while passing them to the queue registered handler.
	19	*/
	20	static void blk_done_softirq(struct softirq_action *h)
	21	{
	22	struct list_head *cpu_list, local_list;
	23
	24	local_irq_disable();
	25	cpu_list = &__get_cpu_var(blk_cpu_done);
	26	list_replace_init(cpu_list, &local_list);
	27	local_irq_enable();
	28
	29	while (!list_empty(&local_list)) {
	30	struct request *rq;
	31
	32	rq = list_entry(local_list.next, struct request, csd.list);
	33	list_del_init(&rq->csd.list);
	34	rq->q->softirq_done_fn(rq);
	35	}
	36	}
	37
	38	#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
	39	static void trigger_softirq(void *data)
	40	{
	41	struct request *rq = data;
	42	unsigned long flags;
	43	struct list_head *list;
	44
	45	local_irq_save(flags);
	46	list = &__get_cpu_var(blk_cpu_done);
	47	list_add_tail(&rq->csd.list, list);
	48
	49	if (list->next == &rq->csd.list)
	50	raise_softirq_irqoff(BLOCK_SOFTIRQ);
	51
	52	local_irq_restore(flags);
	53	}
	54
	55	/*
	56	* Setup and invoke a run of 'trigger_softirq' on the given cpu.
	57	*/
	58	static int raise_blk_irq(int cpu, struct request *rq)
	59	{
	60	if (cpu_online(cpu)) {
	61	struct call_single_data *data = &rq->csd;
	62
	63	data->func = trigger_softirq;
	64	data->info = rq;
	65	data->flags = 0;
	66
6e275637	67	__smp_call_function_single(cpu, data, 0);
c7c22e4d JA	68	return 0;
	69	}
	70
	71	return 1;
	72	}
	73	#else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
	74	static int raise_blk_irq(int cpu, struct request *rq)
	75	{
	76	return 1;
	77	}
	78	#endif
	79
b646fc59 JA	80	static int __cpuinit blk_cpu_notify(struct notifier_block *self,
	81	unsigned long action, void *hcpu)
	82	{
	83	/*
	84	* If a CPU goes away, splice its entries to the current CPU
	85	* and trigger a run of the softirq
	86	*/
	87	if (action == CPU_DEAD \|\| action == CPU_DEAD_FROZEN) {
	88	int cpu = (unsigned long) hcpu;
	89
	90	local_irq_disable();
	91	list_splice_init(&per_cpu(blk_cpu_done, cpu),
	92	&__get_cpu_var(blk_cpu_done));
	93	raise_softirq_irqoff(BLOCK_SOFTIRQ);
	94	local_irq_enable();
	95	}
	96
	97	return NOTIFY_OK;
	98	}
	99
c7c22e4d	100	static struct notifier_block __cpuinitdata blk_cpu_notifier = {
b646fc59 JA	101	.notifier_call = blk_cpu_notify,
	102	};
	103
242f9dcb	104	void __blk_complete_request(struct request *req)
b646fc59	105	{
35ae66e0	106	int ccpu, cpu;
c7c22e4d	107	struct request_queue *q = req->q;
b646fc59 JA	108	unsigned long flags;
b646fc59 JA	109
c7c22e4d	110	BUG_ON(!q->softirq_done_fn);
b646fc59 JA	111
b646fc59 JA	112	local_irq_save(flags);
c7c22e4d	113	cpu = smp_processor_id();
b646fc59	114
c7c22e4d JA	115	/*
	116	* Select completion CPU
	117	*/
5757a6d7	118	if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) {
c7c22e4d	119	ccpu = req->cpu;
35ae66e0	120	if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
5757a6d7	121	ccpu = blk_cpu_to_group(ccpu);
5757a6d7	122	} else
c7c22e4d JA	123	ccpu = cpu;
c7c22e4d JA	124
35ae66e0	125	if (ccpu == cpu) {
c7c22e4d JA	126	struct list_head *list;
	127	do_local:
	128	list = &__get_cpu_var(blk_cpu_done);
	129	list_add_tail(&req->csd.list, list);
	130
	131	/*
	132	* if the list only contains our just added request,
	133	* signal a raise of the softirq. If there are already
	134	* entries there, someone already raised the irq but it
	135	* hasn't run yet.
	136	*/
	137	if (list->next == &req->csd.list)
	138	raise_softirq_irqoff(BLOCK_SOFTIRQ);
	139	} else if (raise_blk_irq(ccpu, req))
	140	goto do_local;
b646fc59 JA	141
	142	local_irq_restore(flags);
	143	}
242f9dcb JA	144
	145	/**
	146	* blk_complete_request - end I/O on a request
	147	* @req: the request being processed
	148	*
	149	* Description:
	150	* Ends all I/O on a request. It does not handle partial completions,
	151	* unless the driver actually implements this in its completion callback
	152	* through requeueing. The actual completion happens out-of-order,
	153	* through a softirq handler. The user must have registered a completion
	154	* callback through blk_queue_softirq_done().
	155	**/
	156	void blk_complete_request(struct request *req)
	157	{
581d4e28 JA	158	if (unlikely(blk_should_fake_timeout(req->q)))
581d4e28 JA	159	return;
242f9dcb JA	160	if (!blk_mark_rq_complete(req))
	161	__blk_complete_request(req);
	162	}
b646fc59 JA	163	EXPORT_SYMBOL(blk_complete_request);
b646fc59 JA	164
3c18ce71	165	static __init int blk_softirq_init(void)
b646fc59 JA	166	{
	167	int i;
	168
	169	for_each_possible_cpu(i)
	170	INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
	171
	172	open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
	173	register_hotcpu_notifier(&blk_cpu_notifier);
	174	return 0;
	175	}
	176	subsys_initcall(blk_softirq_init);