On Tue, Nov 14, 2006 at 12:33:47PM +0100, Pierre Ossman wrote:
> Jens Axboe wrote:
> > What do you mean by "killing off the queue"? As long as the queue can be
> > gotten at, it needs to remain valid. That is what the references are
> > for.
> >
>
> I do:
>
> del_gendisk();
> (wait for queue to become empty, i.e. elv_next_request() == NULL)
> blk_cleanup_queue();
>
> and then assume that the request function will no longer be called for
> this queue.
>
> Suggested patch:
>
> diff --git a/drivers/mmc/mmc_block.c b/drivers/mmc/mmc_block.c
> index f9027c8..5025abe 100644
> --- a/drivers/mmc/mmc_block.c
> +++ b/drivers/mmc/mmc_block.c
> @@ -83,7 +83,6 @@ static void mmc_blk_put(struct mmc_blk_d
> md->usage--;
> if (md->usage == 0) {
> put_disk(md->disk);
> - mmc_cleanup_queue(&md->queue);
> kfree(md);
> }
> mutex_unlock(&open_lock);
> @@ -553,12 +552,11 @@ static void mmc_blk_remove(struct mmc_ca
> if (md) {
> int devidx;
>
> + /* Stop new requests from getting into the queue */
> del_gendisk(md->disk);
>
> - /*
> - * I think this is needed.
> - */
> - md->disk->queue = NULL;
> + /* Then flush out any already in there */
> + mmc_cleanup_queue(&md->queue);
>
> devidx = md->disk->first_minor >> MMC_SHIFT;
> __clear_bit(devidx, dev_use);
You now have a disk which may be in use (and a block device) for which
there is no queue. I couldn't see any locking what so ever in del_gendisk
so it's quite possible that the queue could still be referenced while
the disk is still open.
I also don't think del_gendisk() is sufficient to ensure that no new
requests appear in the queue, which is why I'm setting md->disk->queue
to NULL there.
But shug, I don't know the block layer. Jens is your best bet.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core
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