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SubjectRe: [PATCH 5/8] nbd: use blk_mq_queue_tag_busy_iter
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On Fri, 2019-03-15 at 16:57 +0800, Jianchao Wang wrote:
> blk_mq_tagset_busy_iter is not safe that it could get stale request
> in tags->rqs[]. Use blk_mq_queue_tag_busy_iter here.
>
> Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
> ---
> drivers/block/nbd.c | 2 +
> 1 file changed, 1 insertion(), 1 deletion(-)
>
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 7c9a949..9e7e828 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -747,7 +747,7 @@ static bool nbd_clear_req(struct request *req, void *data, bool reserved)
> static void nbd_clear_que(struct nbd_device *nbd)
> {
> blk_mq_quiesce_queue(nbd->disk->queue);
> - blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
> + blk_mq_queue_tag_busy_iter(nbd->disk->queue, nbd_clear_req, NULL, true);
> blk_mq_unquiesce_queue(nbd->disk->queue);
> dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
> }

Hi Jianchao,

The nbd driver calls nbd_clear_que() after having called sock_shutdown(). So
what makes you think that it's not safe to call blk_mq_tagset_busy_iter()
from nbd_clear_que()?

Thanks,

Bart.

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