From 302ad8cc09339ea261eef58a8d5f4a116a8ffda5 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Wed, 1 Mar 2017 14:22:12 -0500 Subject: [PATCH] nvme: Complete all stuck requests If the nvme driver is shutting down its controller, the drievr will not start the queues up again, preventing blk-mq's hot CPU notifier from making forward progress. To fix that, this patch starts a request_queue freeze when the driver resets a controller so no new requests may enter. The driver will wait for frozen after IO queues are restarted to ensure the queue reference can be reinitialized when nvme requests to unfreeze the queues. If the driver is doing a safe shutdown, the driver will wait for the controller to successfully complete all inflight requests so that we don't unnecessarily fail them. Once the controller has been disabled, the queues will be restarted to force remaining entered requests to end in failure so that blk-mq's hot cpu notifier may progress. Signed-off-by: Keith Busch Reviewed-by: Sagi Grimberg Signed-off-by: Jens Axboe --- drivers/nvme/host/core.c | 47 ++++++++++++++++++++++++++++++++++++++++ drivers/nvme/host/nvme.h | 4 ++++ drivers/nvme/host/pci.c | 33 +++++++++++++++++++++++----- 3 files changed, 79 insertions(+), 5 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 25ec4e585220..9b3b57fef446 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -2344,6 +2344,53 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl) } EXPORT_SYMBOL_GPL(nvme_kill_queues); +void nvme_unfreeze(struct nvme_ctrl *ctrl) +{ + struct nvme_ns *ns; + + mutex_lock(&ctrl->namespaces_mutex); + list_for_each_entry(ns, &ctrl->namespaces, list) + blk_mq_unfreeze_queue(ns->queue); + mutex_unlock(&ctrl->namespaces_mutex); +} +EXPORT_SYMBOL_GPL(nvme_unfreeze); + +void nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl, long timeout) +{ + struct nvme_ns *ns; + + mutex_lock(&ctrl->namespaces_mutex); + list_for_each_entry(ns, &ctrl->namespaces, list) { + timeout = blk_mq_freeze_queue_wait_timeout(ns->queue, timeout); + if (timeout <= 0) + break; + } + mutex_unlock(&ctrl->namespaces_mutex); +} +EXPORT_SYMBOL_GPL(nvme_wait_freeze_timeout); + +void nvme_wait_freeze(struct nvme_ctrl *ctrl) +{ + struct nvme_ns *ns; + + mutex_lock(&ctrl->namespaces_mutex); + list_for_each_entry(ns, &ctrl->namespaces, list) + blk_mq_freeze_queue_wait(ns->queue); + mutex_unlock(&ctrl->namespaces_mutex); +} +EXPORT_SYMBOL_GPL(nvme_wait_freeze); + +void nvme_start_freeze(struct nvme_ctrl *ctrl) +{ + struct nvme_ns *ns; + + mutex_lock(&ctrl->namespaces_mutex); + list_for_each_entry(ns, &ctrl->namespaces, list) + blk_mq_freeze_queue_start(ns->queue); + mutex_unlock(&ctrl->namespaces_mutex); +} +EXPORT_SYMBOL_GPL(nvme_start_freeze); + void nvme_stop_queues(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index a3da1e90b99d..2aa20e3e5675 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -294,6 +294,10 @@ void nvme_queue_async_events(struct nvme_ctrl *ctrl); void nvme_stop_queues(struct nvme_ctrl *ctrl); void nvme_start_queues(struct nvme_ctrl *ctrl); void nvme_kill_queues(struct nvme_ctrl *ctrl); +void nvme_unfreeze(struct nvme_ctrl *ctrl); +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); #define NVME_QID_ANY -1 struct request *nvme_alloc_request(struct request_queue *q, diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index eee8f8426ff2..26a5fd05fe88 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -1675,21 +1675,34 @@ static void nvme_pci_disable(struct nvme_dev *dev) static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown) { int i, queues; - u32 csts = -1; + bool dead = true; + struct pci_dev *pdev = to_pci_dev(dev->dev); del_timer_sync(&dev->watchdog_timer); mutex_lock(&dev->shutdown_lock); - if (pci_is_enabled(to_pci_dev(dev->dev))) { - nvme_stop_queues(&dev->ctrl); - csts = readl(dev->bar + NVME_REG_CSTS); + if (pci_is_enabled(pdev)) { + u32 csts = readl(dev->bar + NVME_REG_CSTS); + + if (dev->ctrl.state == NVME_CTRL_LIVE) + 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 && shutdown) + nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT); + nvme_stop_queues(&dev->ctrl); + queues = dev->online_queues - 1; for (i = dev->queue_count - 1; i > 0; i--) nvme_suspend_queue(dev->queues[i]); - if (csts & NVME_CSTS_CFS || !(csts & NVME_CSTS_RDY)) { + if (dead) { /* A device might become IO incapable very soon during * probe, before the admin queue is configured. Thus, * queue_count can be 0 here. @@ -1704,6 +1717,14 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown) blk_mq_tagset_busy_iter(&dev->tagset, nvme_cancel_request, &dev->ctrl); blk_mq_tagset_busy_iter(&dev->admin_tagset, nvme_cancel_request, &dev->ctrl); + + /* + * The driver will not be starting up queues again if shutting down so + * must flush all entered requests to their failed completion to avoid + * deadlocking blk-mq hot-cpu notifier. + */ + if (shutdown) + nvme_start_queues(&dev->ctrl); mutex_unlock(&dev->shutdown_lock); } @@ -1826,7 +1847,9 @@ static void nvme_reset_work(struct work_struct *work) nvme_remove_namespaces(&dev->ctrl); } else { nvme_start_queues(&dev->ctrl); + nvme_wait_freeze(&dev->ctrl); nvme_dev_add(dev); + nvme_unfreeze(&dev->ctrl); } if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_LIVE)) { -- 2.20.1