nvme-rdma: use ib_client API to detect device removal

Change nvme-rdma to use the IB Client API to detect device removal.
This has the wonderful benefit of being able to blow away all the
ib/rdma_cm resources for the device being removed.  No craziness about
not destroying the cm_id handling the event.  No deadlocks due to broken
iw_cm/rdma_cm/iwarp dependencies.  And no need to have a bound cm_id
around during controller recovery/reconnect to catch device removal
events.

We don't use the device_add aspect of the ib_client service since we only
want to create resources for an IB device if we have a target utilizing
that device.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

1 files changed, 40 insertions, 68 deletions

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index eeb08b658640..d6bdf55a969e 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1320,64 +1320,6 @@ out_destroy_queue_ib:
         return ret;
 }
 
-/**
- * nvme_rdma_device_unplug() - Handle RDMA device unplug
- * @queue:      Queue that owns the cm_id that caught the event
- *
- * DEVICE_REMOVAL event notifies us that the RDMA device is about
- * to unplug so we should take care of destroying our RDMA resources.
- * This event will be generated for each allocated cm_id.
- *
- * In our case, the RDMA resources are managed per controller and not
- * only per queue. So the way we handle this is we trigger an implicit
- * controller deletion upon the first DEVICE_REMOVAL event we see, and
- * hold the event inflight until the controller deletion is completed.
- *
- * One exception that we need to handle is the destruction of the cm_id
- * that caught the event. Since we hold the callout until the controller
- * deletion is completed, we'll deadlock if the controller deletion will
- * call rdma_destroy_id on this queue's cm_id. Thus, we claim ownership
- * of destroying this queue before-hand, destroy the queue resources,
- * then queue the controller deletion which won't destroy this queue and
- * we destroy the cm_id implicitely by returning a non-zero rc to the callout.
- */
-static int nvme_rdma_device_unplug(struct nvme_rdma_queue *queue)
-{
-        struct nvme_rdma_ctrl *ctrl = queue->ctrl;
-        int ret = 0;
-
-        /* Own the controller deletion */
-        if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_DELETING))
-                return 0;
-
-        dev_warn(ctrl->ctrl.device,
-                "Got rdma device removal event, deleting ctrl\n");
-
-        /* Get rid of reconnect work if its running */
-        cancel_delayed_work_sync(&ctrl->reconnect_work);
-
-        /* Disable the queue so ctrl delete won't free it */
-        if (!test_and_set_bit(NVME_RDMA_Q_DELETING, &queue->flags)) {
-                /* Free this queue ourselves */
-                nvme_rdma_stop_queue(queue);
-                nvme_rdma_destroy_queue_ib(queue);
-
-                /* Return non-zero so the cm_id will destroy implicitly */
-                ret = 1;
-        }
-
-        /*
-         * Queue controller deletion. Keep a reference until all
-         * work is flushed since delete_work will free the ctrl mem
-         */
-        kref_get(&ctrl->ctrl.kref);
-        queue_work(nvme_rdma_wq, &ctrl->delete_work);
-        flush_work(&ctrl->delete_work);
-        nvme_put_ctrl(&ctrl->ctrl);
-
-        return ret;
-}
-
 static int nvme_rdma_cm_handler(struct rdma_cm_id *cm_id,
                 struct rdma_cm_event *ev)
 {
@@ -1419,8 +1361,8 @@ static int nvme_rdma_cm_handler(struct rdma_cm_id *cm_id,
                 nvme_rdma_error_recovery(queue->ctrl);
                 break;
         case RDMA_CM_EVENT_DEVICE_REMOVAL:
-                /* return 1 means impliciy CM ID destroy */
-                return nvme_rdma_device_unplug(queue);
+                /* device removal is handled via the ib_client API */
+                break;
         default:
                 dev_err(queue->ctrl->ctrl.device,
                         "Unexpected RDMA CM event (%d)\n", ev->event);
@@ -2030,27 +1972,57 @@ static struct nvmf_transport_ops nvme_rdma_transport = {
         .create_ctrl    = nvme_rdma_create_ctrl,
 };
 
+static void nvme_rdma_add_one(struct ib_device *ib_device)
+{
+}
+
+static void nvme_rdma_remove_one(struct ib_device *ib_device, void *client_data)
+{
+        struct nvme_rdma_ctrl *ctrl;
+
+        /* Delete all controllers using this device */
+        mutex_lock(&nvme_rdma_ctrl_mutex);
+        list_for_each_entry(ctrl, &nvme_rdma_ctrl_list, list) {
+                if (ctrl->device->dev != ib_device)
+                        continue;
+                dev_info(ctrl->ctrl.device,
+                        "Removing ctrl: NQN \"%s\", addr %pISp\n",
+                        ctrl->ctrl.opts->subsysnqn, &ctrl->addr);
+                __nvme_rdma_del_ctrl(ctrl);
+        }
+        mutex_unlock(&nvme_rdma_ctrl_mutex);
+
+        flush_workqueue(nvme_rdma_wq);
+}
+
+static struct ib_client nvme_rdma_ib_client = {
+        .name   = "nvme_rdma",
+        .add = nvme_rdma_add_one,
+        .remove = nvme_rdma_remove_one
+};
+
 static int __init nvme_rdma_init_module(void)
 {
+        int ret;
+
         nvme_rdma_wq = create_workqueue("nvme_rdma_wq");
         if (!nvme_rdma_wq)
                 return -ENOMEM;
 
+        ret = ib_register_client(&nvme_rdma_ib_client);
+        if (ret) {
+                destroy_workqueue(nvme_rdma_wq);
+                return ret;
+        }
+
         nvmf_register_transport(&nvme_rdma_transport);
         return 0;
 }
 
 static void __exit nvme_rdma_cleanup_module(void)
 {
-        struct nvme_rdma_ctrl *ctrl;
-
         nvmf_unregister_transport(&nvme_rdma_transport);
-
-        mutex_lock(&nvme_rdma_ctrl_mutex);
-        list_for_each_entry(ctrl, &nvme_rdma_ctrl_list, list)
-                __nvme_rdma_del_ctrl(ctrl);
-        mutex_unlock(&nvme_rdma_ctrl_mutex);
-
+        ib_unregister_client(&nvme_rdma_ib_client);
         destroy_workqueue(nvme_rdma_wq);
 }