nvme: introduce a controller state machine

Replace the adhoc flags in the PCI driver with a state machine in the
core code.  Based on code from Sagi Grimberg for the Fabrics driver.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Acked-by Jon Derrick: <jonathan.derrick@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 20559ad..bd8f598 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -58,6 +58,55 @@ static DEFINE_SPINLOCK(dev_list_lock);
 
 static struct class *nvme_class;
 
+bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
+               enum nvme_ctrl_state new_state)
+{
+       enum nvme_ctrl_state old_state = ctrl->state;
+       bool changed = false;
+
+       spin_lock_irq(&ctrl->lock);
+       switch (new_state) {
+       case NVME_CTRL_LIVE:
+               switch (old_state) {
+               case NVME_CTRL_RESETTING:
+                       changed = true;
+                       /* FALLTHRU */
+               default:
+                       break;
+               }
+               break;
+       case NVME_CTRL_RESETTING:
+               switch (old_state) {
+               case NVME_CTRL_NEW:
+               case NVME_CTRL_LIVE:
+                       changed = true;
+                       /* FALLTHRU */
+               default:
+                       break;
+               }
+               break;
+       case NVME_CTRL_DELETING:
+               switch (old_state) {
+               case NVME_CTRL_LIVE:
+               case NVME_CTRL_RESETTING:
+                       changed = true;
+                       /* FALLTHRU */
+               default:
+                       break;
+               }
+               break;
+       default:
+               break;
+       }
+       spin_unlock_irq(&ctrl->lock);
+
+       if (changed)
+               ctrl->state = new_state;
+
+       return changed;
+}
+EXPORT_SYMBOL_GPL(nvme_change_ctrl_state);
+
 static void nvme_free_ns(struct kref *kref)
 {
        struct nvme_ns *ns = container_of(kref, struct nvme_ns, kref);
@@ -1583,6 +1632,8 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 {
        int ret;
 
+       ctrl->state = NVME_CTRL_NEW;
+       spin_lock_init(&ctrl->lock);
        INIT_LIST_HEAD(&ctrl->namespaces);
        mutex_init(&ctrl->namespaces_mutex);
        kref_init(&ctrl->kref);

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 41e922b..4135626 100644 (file)
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -67,7 +67,16 @@ enum nvme_quirks {
        NVME_QUIRK_DISCARD_ZEROES               = (1 << 2),
 };
 
+enum nvme_ctrl_state {
+       NVME_CTRL_NEW,
+       NVME_CTRL_LIVE,
+       NVME_CTRL_RESETTING,
+       NVME_CTRL_DELETING,
+};
+
 struct nvme_ctrl {
+       enum nvme_ctrl_state state;
+       spinlock_t lock;
        const struct nvme_ctrl_ops *ops;
        struct request_queue *admin_q;
        struct device *dev;
@@ -187,6 +196,8 @@ static inline bool nvme_req_needs_retry(struct request *req, u16 status)
                (jiffies - req->start_time) < req->timeout;
 }
 
+bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
+               enum nvme_ctrl_state new_state);
 int nvme_disable_ctrl(struct nvme_ctrl *ctrl, u64 cap);
 int nvme_enable_ctrl(struct nvme_ctrl *ctrl, u64 cap);
 int nvme_shutdown_ctrl(struct nvme_ctrl *ctrl);

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 321b8e0..0cee236 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -102,11 +102,6 @@ struct nvme_dev {
        dma_addr_t cmb_dma_addr;
        u64 cmb_size;
        u32 cmbsz;
-       unsigned long flags;
-
-#define NVME_CTRL_RESETTING    0
-#define NVME_CTRL_REMOVING     1
-
        struct nvme_ctrl ctrl;
        struct completion ioq_wait;
 };
@@ -277,9 +272,8 @@ static void nvme_queue_scan(struct nvme_dev *dev)
         * Do not queue new scan work when a controller is reset during
         * removal.
         */
-       if (test_bit(NVME_CTRL_REMOVING, &dev->flags))
-               return;
-       queue_work(nvme_workq, &dev->scan_work);
+       if (dev->ctrl.state != NVME_CTRL_DELETING)
+               queue_work(nvme_workq, &dev->scan_work);
 }
 
 static void nvme_complete_async_event(struct nvme_dev *dev,
@@ -901,7 +895,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
         * cancellation error. All outstanding requests are completed on
         * shutdown, so we return BLK_EH_HANDLED.
         */
-       if (test_bit(NVME_CTRL_RESETTING, &dev->flags)) {
+       if (dev->ctrl.state == NVME_CTRL_RESETTING) {
                dev_warn(dev->ctrl.device,
                         "I/O %d QID %d timeout, disable controller\n",
                         req->tag, nvmeq->qid);
@@ -1835,7 +1829,7 @@ static void nvme_reset_work(struct work_struct *work)
        struct nvme_dev *dev = container_of(work, struct nvme_dev, reset_work);
        int result = -ENODEV;
 
-       if (WARN_ON(test_bit(NVME_CTRL_RESETTING, &dev->flags)))
+       if (WARN_ON(dev->ctrl.state == NVME_CTRL_RESETTING))
                goto out;
 
        /*
@@ -1845,7 +1839,8 @@ static void nvme_reset_work(struct work_struct *work)
        if (dev->ctrl.ctrl_config & NVME_CC_ENABLE)
                nvme_dev_disable(dev, false);
 
-       set_bit(NVME_CTRL_RESETTING, &dev->flags);
+       if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING))
+               goto out;
 
        result = nvme_pci_enable(dev);
        if (result)
@@ -1894,7 +1889,10 @@ static void nvme_reset_work(struct work_struct *work)
                nvme_dev_add(dev);
        }
 
-       clear_bit(NVME_CTRL_RESETTING, &dev->flags);
+       if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_LIVE)) {
+               dev_warn(dev->ctrl.device, "failed to mark controller live\n");
+               goto out;
+       }
        return;
 
  out:
@@ -2067,7 +2065,8 @@ static void nvme_remove(struct pci_dev *pdev)
 
        del_timer_sync(&dev->watchdog_timer);
 
-       set_bit(NVME_CTRL_REMOVING, &dev->flags);
+       nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
+
        pci_set_drvdata(pdev, NULL);
        flush_work(&dev->async_work);
        flush_work(&dev->scan_work);