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

    -
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