// SPDX-License-Identifier: GPL-2.0/* * 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); bool __blk_should_fake_timeout(struct request_queue *q){	return should_fail(&fail_io_timeout, 1);}EXPORT_SYMBOL_GPL(__blk_should_fake_timeout); 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);		if (val)			blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);		else			blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);	} 	return count;} #endif /* CONFIG_FAIL_IO_TIMEOUT */ /** * blk_abort_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_request. */void blk_abort_request(struct request *req){	/*	 * All we need to ensure is that timeout scan takes place	 * immediately and that scan sees the new timeout value.	 * No need for fancy synchronizations.	 */	WRITE_ONCE(req->deadline, jiffies);	kblockd_schedule_work(&req->q->timeout_work);}EXPORT_SYMBOL_GPL(blk_abort_request); static unsigned long blk_timeout_mask __read_mostly; static int __init blk_timeout_init(void){	blk_timeout_mask = roundup_pow_of_two(HZ) - 1;	return 0;} late_initcall(blk_timeout_init); /* * Just a rough estimate, we don't care about specific values for timeouts. */static inline unsigned long blk_round_jiffies(unsigned long j){	return (j + blk_timeout_mask) + 1;} unsigned long blk_rq_timeout(unsigned long timeout){	unsigned long maxt; 	maxt = blk_round_jiffies(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; 	/*	 * 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->rq_flags &= ~RQF_TIMED_OUT; 	expiry = jiffies + req->timeout;	WRITE_ONCE(req->deadline, expiry); 	/*	 * 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(blk_round_jiffies(expiry)); 	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);	} }