From: Keith Busch <kbusch@kernel.org>

Date: Wed, 4 Sep 2019 10:06:11 -0600

Subject: [PATCH] nvme: Wait for reset state when required

Git-commit: c1ac9a4b0797ca8bb4470f863a5f78ef1ab13bed

Patch-mainline: v5.4-rc4

References: bsc#1169045

Prevent simultaneous controller disabling/enabling tasks from interfering

with each other through a function to wait until the task successfully

transitioned the controller to the RESETTING state. This ensures disabling

the controller will not be interrupted by another reset path, otherwise

a concurrent reset may leave the controller in the wrong state.

Tested-by: Edmund Nadolski <edmund.nadolski@intel.com>

Reviewed-by: Christoph Hellwig <hch@lst.de>

Signed-off-by: Keith Busch <kbusch@kernel.org>

Acked-by: Hannes Reinecke <hare@suse.com>

---

 drivers/nvme/host/core.c | 41 +++++++++++++++++++++++++++++++++++++++--

 drivers/nvme/host/nvme.h |  4 ++++

 drivers/nvme/host/pci.c  | 46 +++++++++++++++++++++++++++++++---------------

 3 files changed, 74 insertions(+), 17 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c

index e94fa693dd4b..fa7ba09dca77 100644

--- a/drivers/nvme/host/core.c

+++ b/drivers/nvme/host/core.c

@@ -126,7 +126,7 @@ static void nvme_queue_scan(struct nvme_ctrl *ctrl)

  * code paths that can't be interrupted by other reset attempts. A hot removal

  * may prevent this from succeeding.

  */

-static int nvme_try_sched_reset(struct nvme_ctrl *ctrl)

+int nvme_try_sched_reset(struct nvme_ctrl *ctrl)

 {

 	if (ctrl->state != NVME_CTRL_RESETTING)

 		return -EBUSY;

@@ -134,6 +134,7 @@ static int nvme_try_sched_reset(struct nvme_ctrl *ctrl)

 		return -EBUSY;

 	return 0;

 }

+EXPORT_SYMBOL_GPL(nvme_try_sched_reset);

 int nvme_reset_ctrl(struct nvme_ctrl *ctrl)

 {

@@ -384,8 +385,10 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,

 		break;

 	}

-	if (changed)

+	if (changed) {

 		ctrl->state = new_state;

+		wake_up_all(&ctrl->state_wq);

+	}

 	spin_unlock_irqrestore(&ctrl->lock, flags);

 	if (changed && ctrl->state == NVME_CTRL_LIVE)

@@ -394,6 +397,39 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,

 }

 EXPORT_SYMBOL_GPL(nvme_change_ctrl_state);

+/*

+ * Returns true for sink states that can't ever transition back to live.

+ */

+static bool nvme_state_terminal(struct nvme_ctrl *ctrl)

+{

+	switch (ctrl->state) {

+	case NVME_CTRL_NEW:

+	case NVME_CTRL_LIVE:

+	case NVME_CTRL_RESETTING:

+	case NVME_CTRL_CONNECTING:

+		return false;

+	case NVME_CTRL_DELETING:

+	case NVME_CTRL_DEAD:

+		return true;

+	default:

+		WARN_ONCE(1, "Unhandled ctrl state:%d", ctrl->state);

+		return true;

+	}

+}

+

+/*

+ * Waits for the controller state to be resetting, or returns false if it is

+ * not possible to ever transition to that state.

+ */

+bool nvme_wait_reset(struct nvme_ctrl *ctrl)

+{

+	wait_event(ctrl->state_wq,

+		   nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING) ||

+		   nvme_state_terminal(ctrl));

+	return ctrl->state == NVME_CTRL_RESETTING;

+}

+EXPORT_SYMBOL_GPL(nvme_wait_reset);

+

 static void nvme_free_ns_head(struct kref *ref)

 {

 	struct nvme_ns_head *head =

@@ -3998,6 +4034,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,

 	INIT_WORK(&ctrl->async_event_work, nvme_async_event_work);

 	INIT_WORK(&ctrl->fw_act_work, nvme_fw_act_work);

 	INIT_WORK(&ctrl->delete_work, nvme_delete_ctrl_work);

+	init_waitqueue_head(&ctrl->state_wq);

 	INIT_DELAYED_WORK(&ctrl->ka_work, nvme_keep_alive_work);

 	memset(&ctrl->ka_cmd, 0, sizeof(ctrl->ka_cmd));

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h

index 2ba577271ada..22e8401352c2 100644

--- a/drivers/nvme/host/nvme.h

+++ b/drivers/nvme/host/nvme.h

@@ -15,6 +15,7 @@

 #include <linux/sed-opal.h>

 #include <linux/fault-inject.h>

 #include <linux/rcupdate.h>

+#include <linux/wait.h>

 #include <trace/events/block.h>

@@ -198,6 +199,7 @@ struct nvme_ctrl {

 	struct cdev cdev;

 	struct work_struct reset_work;

 	struct work_struct delete_work;

+	wait_queue_head_t state_wq;

 	struct nvme_subsystem *subsys;

 	struct list_head subsys_entry;

@@ -448,6 +450,7 @@ void nvme_complete_rq(struct request *req);

 bool nvme_cancel_request(struct request *req, void *data, bool reserved);

 bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,

 		enum nvme_ctrl_state new_state);

+bool nvme_wait_reset(struct nvme_ctrl *ctrl);

 int nvme_disable_ctrl(struct nvme_ctrl *ctrl);

 int nvme_enable_ctrl(struct nvme_ctrl *ctrl);

 int nvme_shutdown_ctrl(struct nvme_ctrl *ctrl);

@@ -498,6 +501,7 @@ int nvme_set_queue_count(struct nvme_ctrl *ctrl, int *count);

 void nvme_stop_keep_alive(struct nvme_ctrl *ctrl);

 int nvme_reset_ctrl(struct nvme_ctrl *ctrl);

 int nvme_reset_ctrl_sync(struct nvme_ctrl *ctrl);

+int nvme_try_sched_reset(struct nvme_ctrl *ctrl);

 int nvme_delete_ctrl(struct nvme_ctrl *ctrl);

 int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp,

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c

index e7e79d6af9ba..4b181969c432 100644

--- a/drivers/nvme/host/pci.c

+++ b/drivers/nvme/host/pci.c

@@ -2463,6 +2463,14 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)

 	mutex_unlock(&dev->shutdown_lock);

 }

+static int nvme_disable_prepare_reset(struct nvme_dev *dev, bool shutdown)

+{

+	if (!nvme_wait_reset(&dev->ctrl))

+		return -EBUSY;

+	nvme_dev_disable(dev, shutdown);

+	return 0;

+}

+

 static int nvme_setup_prp_pools(struct nvme_dev *dev)

 {

 	dev->prp_page_pool = dma_pool_create("prp list page", dev->dev,

@@ -2510,6 +2518,11 @@ static void nvme_pci_free_ctrl(struct nvme_ctrl *ctrl)

 static void nvme_remove_dead_ctrl(struct nvme_dev *dev)

 {

+	/*

+	 * Set state to deleting now to avoid blocking nvme_wait_reset(), which

+	 * may be holding this pci_dev's device lock.

+	 */

+	nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);

 	nvme_get_ctrl(&dev->ctrl);

 	nvme_dev_disable(dev, false);

 	nvme_kill_queues(&dev->ctrl);

@@ -2835,19 +2848,28 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)

 static void nvme_reset_prepare(struct pci_dev *pdev)

 {

 	struct nvme_dev *dev = pci_get_drvdata(pdev);

-	nvme_dev_disable(dev, false);

+

+	/*

+	 * We don't need to check the return value from waiting for the reset

+	 * state as pci_dev device lock is held, making it impossible to race

+	 * with ->remove().

+	 */

+	nvme_disable_prepare_reset(dev, false);

+	nvme_sync_queues(&dev->ctrl);

 }

 static void nvme_reset_done(struct pci_dev *pdev)

 {

 	struct nvme_dev *dev = pci_get_drvdata(pdev);

-	nvme_reset_ctrl_sync(&dev->ctrl);

+

+	if (!nvme_try_sched_reset(&dev->ctrl))

+		flush_work(&dev->ctrl.reset_work);

 }

 static void nvme_shutdown(struct pci_dev *pdev)

 {

 	struct nvme_dev *dev = pci_get_drvdata(pdev);

-	nvme_dev_disable(dev, true);

+	nvme_disable_prepare_reset(dev, true);

 }

 /*

@@ -2900,7 +2922,7 @@ static int nvme_resume(struct device *dev)

 	if (ndev->last_ps == U32_MAX ||

 	    nvme_set_power_state(ctrl, ndev->last_ps) != 0)

-		nvme_reset_ctrl(ctrl);

+		return nvme_try_sched_reset(&ndev->ctrl);

 	return 0;

 }

@@ -2928,10 +2950,8 @@ static int nvme_suspend(struct device *dev)

 	 */

 	if (pm_suspend_via_firmware() || !ctrl->npss ||

 	    !pcie_aspm_enabled(pdev) ||

-	    (ndev->ctrl.quirks & NVME_QUIRK_SIMPLE_SUSPEND)) {

-		nvme_dev_disable(ndev, true);

-		return 0;

-	}

+	    (ndev->ctrl.quirks & NVME_QUIRK_SIMPLE_SUSPEND))

+		return nvme_disable_prepare_reset(ndev, true);

 	nvme_start_freeze(ctrl);

 	nvme_wait_freeze(ctrl);

@@ -2963,9 +2983,8 @@ static int nvme_suspend(struct device *dev)

 		 * Clearing npss forces a controller reset on resume. The

 		 * correct value will be resdicovered then.

 		 */

-		nvme_dev_disable(ndev, true);

+		ret = nvme_disable_prepare_reset(ndev, true);

 		ctrl->npss = 0;

-		ret = 0;

 	}

 unfreeze:

 	nvme_unfreeze(ctrl);

@@ -2975,9 +2994,7 @@ static int nvme_suspend(struct device *dev)

 static int nvme_simple_suspend(struct device *dev)

 {

 	struct nvme_dev *ndev = pci_get_drvdata(to_pci_dev(dev));

-

-	nvme_dev_disable(ndev, true);

-	return 0;

+	return nvme_disable_prepare_reset(ndev, true);

 }

 static int nvme_simple_resume(struct device *dev)

@@ -2985,8 +3002,7 @@ static int nvme_simple_resume(struct device *dev)

 	struct pci_dev *pdev = to_pci_dev(dev);

 	struct nvme_dev *ndev = pci_get_drvdata(pdev);

-	nvme_reset_ctrl(&ndev->ctrl);

-	return 0;

+	return nvme_try_sched_reset(&ndev->ctrl);

 }

 static const struct dev_pm_ops nvme_dev_pm_ops = {

-- 

2.16.4