[PATCH 4/4] nvme: Add two-pass shutdown support

[Jeremy Allison]

This works with the two-pass shutdown mechanism setup for the PCI
drivers and participates to provide the shutdown_wait
method at the pci_driver structure level.

Adds the new NVME_DISABLE_SHUTDOWN_ASYNC to enum shutdown_type.
Changes the nvme shutdown() method to set the
NVME_CC_SHN_NORMAL bit and then return to the caller when
requested by NVME_DISABLE_SHUTDOWN_ASYNC.

nvme_shutdown_wait() is added to call an internal
nvme_wait_for_shutdown_cmpl() function to synchronously
wait for the device to wait for the NVME_CSTS_SHST_CMPLT bit.

This change speeds up the shutdown in a system which hosts
many controllers.

Signed-off-by: Jeremy Allison <jallison at ciq.com>
Signed-off-by: Tanjore Suresh <tansuresh at google.com>
---
 drivers/nvme/host/core.c | 29 +++++++++++++++++++++++++++--
 drivers/nvme/host/nvme.h |  4 +++-
 drivers/nvme/host/pci.c  | 24 ++++++++++++++++++++++--
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index bc7040da8e74..2ebcd40106b7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2216,7 +2216,7 @@ int nvme_disable_ctrl(struct nvme_ctrl *ctrl, enum shutdown_type shutdown_type)
 	int ret;
 
 	ctrl->ctrl_config &= ~NVME_CC_SHN_MASK;
-	if (shutdown_type == NVME_DISABLE_SHUTDOWN_SYNC)
+	if (shutdown_type != NVME_DISABLE_RESET)
 		ctrl->ctrl_config |= NVME_CC_SHN_NORMAL;
 	else
 		ctrl->ctrl_config &= ~NVME_CC_ENABLE;
@@ -2225,10 +2225,24 @@ int nvme_disable_ctrl(struct nvme_ctrl *ctrl, enum shutdown_type shutdown_type)
 	if (ret)
 		return ret;
 
-	if (shutdown_type == NVME_DISABLE_SHUTDOWN_SYNC) {
+	switch (shutdown_type) {
+	case NVME_DISABLE_SHUTDOWN_ASYNC:
+		/*
+		 * nvme_wait_for_shutdown_cmpl() will read the reply for this.
+		*/
+		return ret;
+	case NVME_DISABLE_SHUTDOWN_SYNC:
+		/*
+		 * Spin on the read of the control register.
+		 */
 		return nvme_wait_ready(ctrl, NVME_CSTS_SHST_MASK,
 				       NVME_CSTS_SHST_CMPLT,
 				       ctrl->shutdown_timeout, "shutdown");
+	case NVME_DISABLE_RESET:
+		/*
+		 * Doing a reset here. Handle below.
+		 */
+		break;
 	}
 	if (ctrl->quirks & NVME_QUIRK_DELAY_BEFORE_CHK_RDY)
 		msleep(NVME_QUIRK_DELAY_AMOUNT);
@@ -2237,6 +2251,17 @@ int nvme_disable_ctrl(struct nvme_ctrl *ctrl, enum shutdown_type shutdown_type)
 }
 EXPORT_SYMBOL_GPL(nvme_disable_ctrl);
 
+int nvme_wait_for_shutdown_cmpl(struct nvme_ctrl *ctrl)
+{
+	ctrl->ctrl_config &= ~NVME_CC_SHN_MASK;
+	ctrl->ctrl_config |= NVME_CC_SHN_NORMAL;
+
+	return nvme_wait_ready(ctrl, NVME_CSTS_SHST_MASK,
+			       NVME_CSTS_SHST_CMPLT,
+			       ctrl->shutdown_timeout, "shutdown");
+}
+EXPORT_SYMBOL_GPL(nvme_wait_for_shutdown_cmpl);
+
 int nvme_enable_ctrl(struct nvme_ctrl *ctrl)
 {
 	unsigned dev_page_min;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index d880f1ee08d4..adbff23532de 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -189,7 +189,8 @@ enum {
 
 enum shutdown_type {
 	NVME_DISABLE_RESET = 0,
-	NVME_DISABLE_SHUTDOWN_SYNC = 1
+	NVME_DISABLE_SHUTDOWN_SYNC = 1,
+	NVME_DISABLE_SHUTDOWN_ASYNC = 2
 };
 
 static inline struct nvme_request *nvme_req(struct request *req)
@@ -756,6 +757,7 @@ void nvme_cancel_admin_tagset(struct nvme_ctrl *ctrl);
 bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
 		enum nvme_ctrl_state new_state);
 int nvme_disable_ctrl(struct nvme_ctrl *ctrl, enum shutdown_type shutdown_type);
+int nvme_wait_for_shutdown_cmpl(struct nvme_ctrl *ctrl);
 int nvme_enable_ctrl(struct nvme_ctrl *ctrl);
 int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 		const struct nvme_ctrl_ops *ops, unsigned long quirks);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 77b015affb0b..9cb4436710dd 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2586,7 +2586,7 @@ static void nvme_dev_disable(struct nvme_dev *dev, enum shutdown_type shutdown_t
 		 * Give the controller a chance to complete all entered requests
 		 * if doing a safe shutdown.
 		 */
-		if (!dead && (shutdown_type == NVME_DISABLE_SHUTDOWN_SYNC))
+		if (!dead && (shutdown_type != NVME_DISABLE_RESET))
 			nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT);
 	}
 
@@ -3100,7 +3100,26 @@ static void nvme_shutdown(struct pci_dev *pdev)
 {
 	struct nvme_dev *dev = pci_get_drvdata(pdev);
 
-	nvme_disable_prepare_reset(dev, NVME_DISABLE_SHUTDOWN_SYNC);
+	nvme_disable_prepare_reset(dev, NVME_DISABLE_SHUTDOWN_ASYNC);
+}
+
+static void nvme_shutdown_wait(struct pci_dev *pdev)
+{
+	struct nvme_dev *dev = pci_get_drvdata(pdev);
+
+	mutex_lock(&dev->shutdown_lock);
+	nvme_wait_for_shutdown_cmpl(&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.
+	 */
+	nvme_unquiesce_io_queues(&dev->ctrl);
+	if (dev->ctrl.admin_q && !blk_queue_dying(dev->ctrl.admin_q))
+		nvme_unquiesce_admin_queue(&dev->ctrl);
+
+	mutex_unlock(&dev->shutdown_lock);
 }
 
 /*
@@ -3492,6 +3511,7 @@ static struct pci_driver nvme_driver = {
 	.probe		= nvme_probe,
 	.remove		= nvme_remove,
 	.shutdown	= nvme_shutdown,
+	.shutdown_wait  = nvme_shutdown_wait,
 	.driver		= {
 		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
 #ifdef CONFIG_PM_SLEEP
-- 
2.39.3