// 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
  ", 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);
  	}

  
  }