On Wed, Sep 05, 2018 at 12:09:46PM +0800, Jianchao Wang wrote: > nvme_dev_disable freezes queues to prevent new IO. nvme_reset_work > will unfreeze and wait to drain the queues. However, if IO timeout > at the moment, no body could do recovery as nvme_reset_work is > waiting. We will encounter IO hang. > > To avoid this scenario, use queue close to prevent new IO which > doesn't need to drain the queues. And just use queue freeze to > try to wait for in-flight IO for shutdown case. > > Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx> > --- > drivers/nvme/host/core.c | 22 ++++++++++++++++++++++ > drivers/nvme/host/nvme.h | 3 +++ > drivers/nvme/host/pci.c | 27 ++++++++++++++------------- > 3 files changed, 39 insertions(+), 13 deletions(-) > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index dd8ec1d..ce5b35b 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -3602,6 +3602,28 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl) > } > EXPORT_SYMBOL_GPL(nvme_kill_queues); > > +void nvme_close_queues(struct nvme_ctrl *ctrl) > +{ > + struct nvme_ns *ns; > + > + down_read(&ctrl->namespaces_rwsem); > + list_for_each_entry(ns, &ctrl->namespaces, list) > + blk_set_queue_closed(ns->queue); > + up_read(&ctrl->namespaces_rwsem); > +} > +EXPORT_SYMBOL_GPL(nvme_close_queues); > + > +void nvme_open_queues(struct nvme_ctrl *ctrl) > +{ > + struct nvme_ns *ns; > + > + down_read(&ctrl->namespaces_rwsem); > + list_for_each_entry(ns, &ctrl->namespaces, list) > + blk_clear_queue_closed(ns->queue); > + up_read(&ctrl->namespaces_rwsem); > +} > +EXPORT_SYMBOL_GPL(nvme_open_queues); > + > void nvme_unfreeze(struct nvme_ctrl *ctrl) > { > struct nvme_ns *ns; > diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h > index bb4a200..fcd44cb 100644 > --- a/drivers/nvme/host/nvme.h > +++ b/drivers/nvme/host/nvme.h > @@ -437,6 +437,9 @@ void nvme_wait_freeze(struct nvme_ctrl *ctrl); > void nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl, long timeout); > void nvme_start_freeze(struct nvme_ctrl *ctrl); > > +void nvme_close_queues(struct nvme_ctrl *ctrl); > +void nvme_open_queues(struct nvme_ctrl *ctrl); > + > #define NVME_QID_ANY -1 > struct request *nvme_alloc_request(struct request_queue *q, > struct nvme_command *cmd, blk_mq_req_flags_t flags, int qid); > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index d668682..c0ccd04 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -2145,23 +2145,25 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown) > struct pci_dev *pdev = to_pci_dev(dev->dev); > > mutex_lock(&dev->shutdown_lock); > + nvme_close_queues(&dev->ctrl); > if (pci_is_enabled(pdev)) { > u32 csts = readl(dev->bar + NVME_REG_CSTS); > > - if (dev->ctrl.state == NVME_CTRL_LIVE || > - dev->ctrl.state == NVME_CTRL_RESETTING) > - nvme_start_freeze(&dev->ctrl); > dead = !!((csts & NVME_CSTS_CFS) || !(csts & NVME_CSTS_RDY) || > pdev->error_state != pci_channel_io_normal); > - } > > - /* > - * Give the controller a chance to complete all entered requests if > - * doing a safe shutdown. > - */ > - if (!dead) { > - if (shutdown) > - nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT); > + if (dev->ctrl.state == NVME_CTRL_LIVE || > + dev->ctrl.state == NVME_CTRL_RESETTING) { > + /* > + * Give the controller a chance to complete all entered > + * requests if doing a safe shutdown. > + */ > + if (!dead && shutdown) { > + nvme_start_freeze(&dev->ctrl); > + nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT); > + nvme_unfreeze(&dev->ctrl); > + } > + } > } > > nvme_stop_queues(&dev->ctrl); > @@ -2328,11 +2330,9 @@ static void nvme_reset_work(struct work_struct *work) > new_state = NVME_CTRL_ADMIN_ONLY; > } else { > nvme_start_queues(&dev->ctrl); > - nvme_wait_freeze(&dev->ctrl); > /* hit this only when allocate tagset fails */ > if (nvme_dev_add(dev)) > new_state = NVME_CTRL_ADMIN_ONLY; > - nvme_unfreeze(&dev->ctrl); nvme_dev_add() still may call freeze & unfreeze queue, so your patch can't avoid draining queue completely here. Thanks, Ming