Commit 287922eb authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: defer timeouts to a workqueue 



Timer context is not very useful for drivers to perform any meaningful abort
action from.  So instead of calling the driver from this useless context
defer it to a workqueue as soon as possible.

Note that while a delayed_work item would seem the right thing here I didn't
dare to use it due to the magic in blk_add_timer that pokes deep into timer
internals.  But maybe this encourages Tejun to add a sensible API for that to
the workqueue API and we'll all be fine in the end :)

Contains a major update from Keith Bush:

"This patch removes synchronizing the timeout work so that the timer can
 start a freeze on its own queue. The timer enters the queue, so timer
 context can only start a freeze, but not wait for frozen."

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarKeith Busch <keith.busch@intel.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 8c0b3915

block/blk-core.c

+8 −0
Original line number Original line Diff line number Diff line
@@ -664,6 +664,13 @@ static void blk_queue_usage_counter_release(struct percpu_ref *ref) 
	wake_up_all(&q->mq_freeze_wq);

	wake_up_all(&q->mq_freeze_wq);

}

}





static void blk_rq_timed_out_timer(unsigned long data)

{

	struct request_queue *q = (struct request_queue *)data;



	kblockd_schedule_work(&q->timeout_work);

}



struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)

struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)

{

{

	struct request_queue *q;

	struct request_queue *q;
@@ -825,6 +832,7 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, 
	if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))

	if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))

		goto fail;

		goto fail;





	INIT_WORK(&q->timeout_work, blk_timeout_work);

	q->request_fn		= rfn;

	q->request_fn		= rfn;

	q->prep_rq_fn		= NULL;

	q->prep_rq_fn		= NULL;

	q->unprep_rq_fn		= NULL;

	q->unprep_rq_fn		= NULL;

block/blk-mq.c

+8 −3
Original line number Original line Diff line number Diff line
@@ -615,15 +615,19 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, 
	}

	}

}

}





static void blk_mq_rq_timer(unsigned long priv)

static void blk_mq_timeout_work(struct work_struct *work)

{

{

	struct request_queue *q = (struct request_queue *)priv;

	struct request_queue *q =

		container_of(work, struct request_queue, timeout_work);

	struct blk_mq_timeout_data data = {

	struct blk_mq_timeout_data data = {

		.next		= 0,

		.next		= 0,

		.next_set	= 0,

		.next_set	= 0,

	};

	};

	int i;

	int i;





	if (blk_queue_enter(q, true))

		return;



	blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);

	blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);





	if (data.next_set) {

	if (data.next_set) {
@@ -638,6 +642,7 @@ static void blk_mq_rq_timer(unsigned long priv) 
				blk_mq_tag_idle(hctx);

				blk_mq_tag_idle(hctx);

		}

		}

	}

	}

	blk_queue_exit(q);

}

}





/*

/*
@@ -2015,7 +2020,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, 
		hctxs[i]->queue_num = i;

		hctxs[i]->queue_num = i;

	}

	}





	setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);

	INIT_WORK(&q->timeout_work, blk_mq_timeout_work);

	blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);

	blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);





	q->nr_queues = nr_cpu_ids;

	q->nr_queues = nr_cpu_ids;

block/blk-timeout.c

+6 −2
Original line number Original line Diff line number Diff line
@@ -127,13 +127,16 @@ static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout 
	}

	}

}

}





void blk_rq_timed_out_timer(unsigned long data)

void blk_timeout_work(struct work_struct *work)

{

{

	struct request_queue *q = (struct request_queue *) data;

	struct request_queue *q =

		container_of(work, struct request_queue, timeout_work);

	unsigned long flags, next = 0;

	unsigned long flags, next = 0;

	struct request *rq, *tmp;

	struct request *rq, *tmp;

	int next_set = 0;

	int next_set = 0;





	if (blk_queue_enter(q, true))

		return;

	spin_lock_irqsave(q->queue_lock, flags);

	spin_lock_irqsave(q->queue_lock, flags);





	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)

	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
@@ -143,6 +146,7 @@ void blk_rq_timed_out_timer(unsigned long data) 
		mod_timer(&q->timeout, round_jiffies_up(next));

		mod_timer(&q->timeout, round_jiffies_up(next));





	spin_unlock_irqrestore(q->queue_lock, flags);

	spin_unlock_irqrestore(q->queue_lock, flags);

	blk_queue_exit(q);

}

}





/**

/**

block/blk.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -93,7 +93,7 @@ static inline void blk_flush_integrity(void) 
}

}

#endif

#endif





void blk_rq_timed_out_timer(unsigned long data);

void blk_timeout_work(struct work_struct *work);

unsigned long blk_rq_timeout(unsigned long timeout);

unsigned long blk_rq_timeout(unsigned long timeout);

void blk_add_timer(struct request *req);

void blk_add_timer(struct request *req);

void blk_delete_timer(struct request *);

void blk_delete_timer(struct request *);

include/linux/blkdev.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -407,6 +407,7 @@ struct request_queue { 




	unsigned int		rq_timeout;

	unsigned int		rq_timeout;

	struct timer_list	timeout;

	struct timer_list	timeout;

	struct work_struct	timeout_work;

	struct list_head	timeout_list;

	struct list_head	timeout_list;





	struct list_head	icq_list;

	struct list_head	icq_list;

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