On Fri, May 18, 2018 at 10:38:18AM -0600, Keith Busch wrote:
> This patch fixes races that occur with simultaneous controller
> resets by synchronizing request queues prior to initializing the
> controller. Withouth this, a thread may attempt disabling a controller
> at the same time as we're trying to enable it.
>
> Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
> ---
> drivers/nvme/host/core.c | 21 +++++++++++++++++++--
> drivers/nvme/host/nvme.h | 1 +
> drivers/nvme/host/pci.c | 1 +
> 3 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 99b857e5a7a9..1de68b56b318 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -3471,6 +3471,12 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
> }
> EXPORT_SYMBOL_GPL(nvme_init_ctrl);
>
> +static void nvme_start_queue(struct nvme_ns *ns)
> +{
> + blk_mq_unquiesce_queue(ns->queue);
> + blk_mq_kick_requeue_list(ns->queue);
> +}
> +
> /**
> * nvme_kill_queues(): Ends all namespace queues
> * @ctrl: the dead controller that needs to end
> @@ -3499,7 +3505,7 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl)
> blk_set_queue_dying(ns->queue);
>
> /* Forcibly unquiesce queues to avoid blocking dispatch */
> - blk_mq_unquiesce_queue(ns->queue);
> + nvme_start_queue(ns);
> }
> up_read(&ctrl->namespaces_rwsem);
> }
> @@ -3569,11 +3575,22 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
>
> down_read(&ctrl->namespaces_rwsem);
> list_for_each_entry(ns, &ctrl->namespaces, list)
> - blk_mq_unquiesce_queue(ns->queue);
> + nvme_start_queue(ns);
> up_read(&ctrl->namespaces_rwsem);
> }
> EXPORT_SYMBOL_GPL(nvme_start_queues);
>
> +void nvme_sync_queues(struct nvme_ctrl *ctrl)
> +{
> + struct nvme_ns *ns;
> +
> + down_read(&ctrl->namespaces_rwsem);
> + list_for_each_entry(ns, &ctrl->namespaces, list)
> + blk_sync_queue(ns->queue);
> + up_read(&ctrl->namespaces_rwsem);
> +}
> +EXPORT_SYMBOL_GPL(nvme_sync_queues);
This way can't sync timeout reliably, since timeout events can
come from two NS at the same time, and one may be handled as
RESET_TIMER, and another one can be handled as EH_HANDLED.
Thanks,
Ming
