FreeBSD/Linux Kernel Cross Reference
sys/block/blk-timeout.c

     /*
      * 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"
    
    #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 IS_ERR(dir) ? PTR_ERR(dir) : 0;
    }
    
    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;
    
            ret = q->rq_timed_out_fn(req);
            switch (ret) {
            case BLK_EH_HANDLED:
                    __blk_complete_request(req);
                    break;
            case BLK_EH_RESET_TIMER:
                    blk_clear_rq_complete(req);
                    blk_add_timer(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;
           }
   }
   
   void blk_rq_timed_out_timer(unsigned long data)
   {
           struct request_queue *q = (struct request_queue *) data;
           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) {
                   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))
                                   continue;
                           blk_rq_timed_out(rq);
                   } else if (!next_set || time_after(next, rq->deadline)) {
                           next = rq->deadline;
                           next_set = 1;
                   }
           }
   
           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 (blk_mark_rq_complete(req))
                   return;
           blk_delete_timer(req);
           blk_rq_timed_out(req);
   }
   EXPORT_SYMBOL_GPL(blk_abort_request);
   
   /**
    * 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->rq_timed_out_fn)
                   return;
   
           BUG_ON(!list_empty(&req->timeout_list));
           BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
   
           /*
            * 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;
           list_add_tail(&req->timeout_list, &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 = round_jiffies_up(req->deadline);
   
           if (!timer_pending(&q->timeout) ||
               time_before(expiry, q->timeout.expires))
                   mod_timer(&q->timeout, expiry);
   }
   

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