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- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu May 15 2003 - 22:00:55 EST