[PATCH 5/5] 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 synchronously 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 | 18 ++++++++++++++++--
 drivers/nvme/host/nvme.h |  3 ++-
 drivers/nvme/host/pci.c  | 30 ++++++++++++++++++++++++++++--
 3 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c7d448f186fb..7000adea1e41 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2225,7 +2225,7 @@ 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;
@@ -2234,10 +2234,24 @@ 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_shutdown_wait() 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);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 8c30f9856621..43667d7a471a 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)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 367e322dc818..9052dcf0f70c 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 +3100,32 @@ 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);
+	/*
+	 * Finish waiting for the shutdown request
+	 * initiated in nvme_shutdown() above using
+	 * NVME_DISABLE_SHUTDOWN_ASYNC.
+	 */
+	nvme_wait_ready(&dev->ctrl, NVME_CSTS_SHST_MASK,
+			NVME_CSTS_SHST_CMPLT,
+			dev->ctrl.shutdown_timeout, "shutdown");
+	/*
+	 * 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);
 }
 
 /*
@@ -3494,6 +3519,7 @@ 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