/* * 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); 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_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_RESET_TIMER: blk_add_timer(req); blk_clear_rq_complete(req); break; case BLK_EH_DONE: /* * 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) { const unsigned long deadline = blk_rq_deadline(rq); if (time_after_eq(jiffies, 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, deadline)) { *next_timeout = 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; 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_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 (req->q->mq_ops) { /* * 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. */ blk_rq_set_deadline(req, jiffies); kblockd_schedule_work(&req->q->timeout_work); } else { if (blk_mark_rq_complete(req)) return; 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; blk_rq_set_deadline(req, 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(blk_rq_deadline(req))); 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); } }