Re: 2.5.69-mjb1: undefined reference to `blk_queue_empty'

[Jens Axboe]

On Thu, May 15 2003, Bharata B Rao wrote:
> On Wed, May 14, 2003 at 10:32:24AM +0200, Jens Axboe wrote:
> > 
> > That really has to be locked down as well. For your purpose, I think the
> > use of elv_queue_empty() is much better even though it really is an
> > internal function. The problem mainly comes from AS, that can have non
> > empty queue but still return NULL in elv_next_request().
> > 
> > But yes, it needs to be locked. If you have pinned the other CPUs, then
> > I suppose it should work. But it's still a violation of the locking
> > rules, and one would get in trouble dropping the queue lock from the io
> > scheduler elevator_queue_empty_fn. No one does that currently, but... So
> > please take the lock.
> > 
> 
> Ok, Now we try to acquire the lock and refuse to dump if we don't get 
> the lock.
> 
> --- 2569+mjb1/drivers/dump/dump_blockdev.c.orig	Wed May 14 13:23:36 2003
> +++ 2569+mjb1/drivers/dump/dump_blockdev.c	Thu May 15 09:26:12 2003
> @@ -258,10 +258,19 @@
>  dump_block_silence(struct dump_dev *dev)
>  {
>  	struct dump_blockdev *dump_bdev = DUMP_BDEV(dev);
> +	struct request_queue *q = bdev_get_queue(dump_bdev->bdev);
> +	int ret;
> +
> +	/* If we can't get request queue lock, refuse to take the dump */
> +	if (!spin_trylock(q->queue_lock))
> +		return -EBUSY;
> +
> +	ret = elv_queue_empty(q);
> +	spin_unlock(q->queue_lock);
>  
>  	/* For now we assume we have the device to ourselves */
>  	/* Just a quick sanity check */
> -	if (!blk_queue_empty(bdev_get_queue(dump_bdev->bdev))) {
> +	if (!ret) {
>  		/* i/o in flight - safer to quit */
>  		return -EBUSY;
>  	}

Are interrupts already disabled at this point? If yes, then it looks
fine.

-- 
Jens Axboe