/* * Functions related to generic timeout handling of requests. */#include <linux/kernel.h>#include <linux/module.h>#include <linux/blkdev.h>#include <linux/fault-inject.h> #include "blk.h"#include "blk-mq.h" #ifdef CONFIG_FAIL_IO_TIMEOUT static DECLARE_FAULT_ATTR(fail_io_timeout); static int __init setup_fail_io_timeout(char *str){	return setup_fault_attr(&fail_io_timeout, str);}__setup("fail_io_timeout=", setup_fail_io_timeout); int blk_should_fake_timeout(struct request_queue *q){	if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))		return 0; 	return should_fail(&fail_io_timeout, 1);} static int __init fail_io_timeout_debugfs(void){	struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",						NULL, &fail_io_timeout); 	return PTR_ERR_OR_ZERO(dir);} late_initcall(fail_io_timeout_debugfs); ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,			  char *buf){	struct gendisk *disk = dev_to_disk(dev);	int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags); 	return sprintf(buf, "%d\n", set != 0);} ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,			   const char *buf, size_t count){	struct gendisk *disk = dev_to_disk(dev);	int val; 	if (count) {		struct request_queue *q = disk->queue;		char *p = (char *) buf; 		val = simple_strtoul(p, &p, 10);		spin_lock_irq(q->queue_lock);		if (val)			queue_flag_set(QUEUE_FLAG_FAIL_IO, q);		else			queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);		spin_unlock_irq(q->queue_lock);	} 	return count;} #endif /* CONFIG_FAIL_IO_TIMEOUT */ /* * blk_delete_timer - Delete/cancel timer for a given function. * @req:	request that we are canceling timer for * */void blk_delete_timer(struct request *req){	list_del_init(&req->timeout_list);} static void blk_rq_timed_out(struct request *req){	struct request_queue *q = req->q;	enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER; 	if (q->rq_timed_out_fn)		ret = q->rq_timed_out_fn(req);	switch (ret) {	case BLK_EH_HANDLED:		__blk_complete_request(req);		break;	case BLK_EH_RESET_TIMER:		blk_add_timer(req);		blk_clear_rq_complete(req);		break;	case BLK_EH_NOT_HANDLED:		/*		 * LLD handles this for now but in the future		 * we can send a request msg to abort the command		 * and we can move more of the generic scsi eh code to		 * the blk layer.		 */		break;	default:		printk(KERN_ERR "block: bad eh return: %d\n", ret);		break;	}} static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,			  unsigned int *next_set){	if (time_after_eq(jiffies, rq->deadline)) {		list_del_init(&rq->timeout_list); 		/*		 * Check if we raced with end io completion		 */		if (!blk_mark_rq_complete(rq))			blk_rq_timed_out(rq);	} else if (!*next_set || time_after(*next_timeout, rq->deadline)) {		*next_timeout = rq->deadline;		*next_set = 1;	}} void blk_timeout_work(struct work_struct *work){	struct request_queue *q =		container_of(work, struct request_queue, timeout_work);	unsigned long flags, next = 0;	struct request *rq, *tmp;	int next_set = 0; 	if (blk_queue_enter(q, true))		return;	spin_lock_irqsave(q->queue_lock, flags); 	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)		blk_rq_check_expired(rq, &next, &next_set); 	if (next_set)		mod_timer(&q->timeout, round_jiffies_up(next)); 	spin_unlock_irqrestore(q->queue_lock, flags);	blk_queue_exit(q);} /** * blk_abort_request -- Request request recovery for the specified command * @req:	pointer to the request of interest * * This function requests that the block layer start recovery for the * request by deleting the timer and calling the q's timeout function. * LLDDs who implement their own error recovery MAY ignore the timeout * event if they generated blk_abort_req. Must hold queue lock. */void blk_abort_request(struct request *req){	if (blk_mark_rq_complete(req))		return; 	if (req->q->mq_ops) {		blk_mq_rq_timed_out(req, false);	} else {		blk_delete_timer(req);		blk_rq_timed_out(req);	}}EXPORT_SYMBOL_GPL(blk_abort_request); unsigned long blk_rq_timeout(unsigned long timeout){	unsigned long maxt; 	maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT);	if (time_after(timeout, maxt))		timeout = maxt; 	return timeout;} /** * blk_add_timer - Start timeout timer for a single request * @req:	request that is about to start running. * * Notes: *    Each request has its own timer, and as it is added to the queue, we *    set up the timer. When the request completes, we cancel the timer. */void blk_add_timer(struct request *req){	struct request_queue *q = req->q;	unsigned long expiry; 	if (!q->mq_ops)		lockdep_assert_held(q->queue_lock); 	/* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */	if (!q->mq_ops && !q->rq_timed_out_fn)		return; 	BUG_ON(!list_empty(&req->timeout_list)); 	/*	 * Some LLDs, like scsi, peek at the timeout to prevent a	 * command from being retried forever.	 */	if (!req->timeout)		req->timeout = q->rq_timeout; 	req->deadline = jiffies + req->timeout; 	/*	 * Only the non-mq case needs to add the request to a protected list.	 * For the mq case we simply scan the tag map.	 */	if (!q->mq_ops)		list_add_tail(&req->timeout_list, &req->q->timeout_list); 	/*	 * If the timer isn't already pending or this timeout is earlier	 * than an existing one, modify the timer. Round up to next nearest	 * second.	 */	expiry = blk_rq_timeout(round_jiffies_up(req->deadline)); 	if (!timer_pending(&q->timeout) ||	    time_before(expiry, q->timeout.expires)) {		unsigned long diff = q->timeout.expires - expiry; 		/*		 * Due to added timer slack to group timers, the timer		 * will often be a little in front of what we asked for.		 * So apply some tolerance here too, otherwise we keep		 * modifying the timer because expires for value X		 * will be X + something.		 */		if (!timer_pending(&q->timeout) || (diff >= HZ / 2))			mod_timer(&q->timeout, expiry);	} }