On Wed, May 20, 2009 at 12:01 AM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
>
> We need this in libata to ensure that we don't race between internal
> tag usage and the block layer usage.
>
> Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
> ---
> block/blk-tag.c | 99 ++++++++++++++++++++++++++++++++-------------
> drivers/ata/libata-core.c | 29 +++++++++----
> include/linux/blkdev.h | 3 +
> 3 files changed, 95 insertions(+), 36 deletions(-)
>
> diff --git a/block/blk-tag.c b/block/blk-tag.c
> index e9a7501..208468b 100644
> --- a/block/blk-tag.c
> +++ b/block/blk-tag.c
> @@ -149,6 +149,7 @@ static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
> goto fail;
>
> atomic_set(&tags->refcnt, 1);
> + init_waitqueue_head(&tags->waitq);
> return tags;
> fail:
> kfree(tags);
> @@ -264,6 +265,65 @@ int blk_queue_resize_tags(struct request_queue *q, int new_depth)
> }
> EXPORT_SYMBOL(blk_queue_resize_tags);
>
> +void blk_queue_acquire_tag(struct request_queue *q, int tag)
> +{
> + struct blk_queue_tag *bqt;
> +
> + if (!blk_queue_tagged(q) || !q->queue_tags)
> + return;
> +
> + bqt = q->queue_tags;
> + do {
> + DEFINE_WAIT(wait);
> +
> + if (!test_and_set_bit_lock(tag, bqt->tag_map))
> + break;
> +
> + prepare_to_wait(&bqt->waitq, &wait, TASK_UNINTERRUPTIBLE);
> + if (test_and_set_bit_lock(tag, bqt->tag_map)) {
> + spin_unlock_irq(q->queue_lock);
> + schedule();
> + spin_lock_irq(q->queue_lock);
> + }
> + finish_wait(&bqt->waitq, &wait);
> + } while (1);
> +}
Should blk_queue_acquire_tag() also be EXPORT_SYMBOL like
blk_queue_release_tag() is?
> +
> +void blk_queue_release_tag(struct request_queue *q, int tag)
> +{
...
> +}
> +EXPORT_SYMBOL(blk_queue_release_tag);
thanks,
grant
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