Re: [RFC PATCH v5 03/27] nvme-tcp-offload: Add device scan implementation

From: Dean Balandin <redacted>

As part of create_ctrl(), it scans the registered devices and calls
the claim_dev op on each of them, to find the first devices that matches
the connection params. Once the correct devices is found (claim_dev
returns true), we raise the refcnt of that device and return that device
as the device to be used for ctrl currently being created.

Acked-by: Igor Russkikh <redacted>
Signed-off-by: Dean Balandin <redacted>
Signed-off-by: Prabhakar Kushwaha <redacted>
Signed-off-by: Omkar Kulkarni <redacted>
Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
Signed-off-by: Ariel Elior <redacted>
Signed-off-by: Shai Malin <redacted>
---
  drivers/nvme/host/tcp-offload.c | 94 +++++++++++++++++++++++++++++++++
  1 file changed, 94 insertions(+)

diff --git a/drivers/nvme/host/tcp-offload.c b/drivers/nvme/host/tcp-offload.c
index 711232eba339..aa7cc239abf2 100644
--- a/drivers/nvme/host/tcp-offload.c
+++ b/drivers/nvme/host/tcp-offload.c

@@ -13,6 +13,11 @@
  static LIST_HEAD(nvme_tcp_ofld_devices);
  static DECLARE_RWSEM(nvme_tcp_ofld_devices_rwsem);
  
+static inline struct nvme_tcp_ofld_ctrl *to_tcp_ofld_ctrl(struct nvme_ctrl *nctrl)
+{
+	return container_of(nctrl, struct nvme_tcp_ofld_ctrl, nctrl);
+}
+
  /**
   * nvme_tcp_ofld_register_dev() - NVMeTCP Offload Library registration
   * function.

@@ -98,6 +103,94 @@ void nvme_tcp_ofld_req_done(struct nvme_tcp_ofld_req *req,
  	/* Placeholder - complete request with/without error */
  }
  
+struct nvme_tcp_ofld_dev *
+nvme_tcp_ofld_lookup_dev(struct nvme_tcp_ofld_ctrl *ctrl)
+{
+	struct nvme_tcp_ofld_dev *dev;
+
+	down_read(&nvme_tcp_ofld_devices_rwsem);
+	list_for_each_entry(dev, &nvme_tcp_ofld_devices, entry) {
+		if (dev->ops->claim_dev(dev, &ctrl->conn_params)) {
+			/* Increase driver refcnt */
+			if (!try_module_get(dev->ops->module)) {

+				pr_err("try_module_get failed\n");
+				dev = NULL;
+			}
+
+			goto out;
+		}
+	}
+
+	dev = NULL;
+out:
+	up_read(&nvme_tcp_ofld_devices_rwsem);
+
+	return dev;
+}
+
+static int nvme_tcp_ofld_setup_ctrl(struct nvme_ctrl *nctrl, bool new)
+{
+	/* Placeholder - validates inputs and creates admin and IO queues */
+
+	return 0;
+}
+
+static struct nvme_ctrl *
+nvme_tcp_ofld_create_ctrl(struct device *ndev, struct nvmf_ctrl_options *opts)
+{
+	struct nvme_tcp_ofld_ctrl *ctrl;
+	struct nvme_tcp_ofld_dev *dev;
+	struct nvme_ctrl *nctrl;
+	int rc = 0;
+
+	ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl)
+		return ERR_PTR(-ENOMEM);
+
+	nctrl = &ctrl->nctrl;
+
+	/* Init nvme_tcp_ofld_ctrl and nvme_ctrl params based on received opts */
+
+	/* Find device that can reach the dest addr */
+	dev = nvme_tcp_ofld_lookup_dev(ctrl);
+	if (!dev) {
+		pr_info("no device found for addr %s:%s.\n",
+			opts->traddr, opts->trsvcid);
+		rc = -EINVAL;
+		goto out_free_ctrl;
+	}
+
+	ctrl->dev = dev;
+
+	if (ctrl->dev->ops->max_hw_sectors)
+		nctrl->max_hw_sectors = ctrl->dev->ops->max_hw_sectors;
+	if (ctrl->dev->ops->max_segments)
+		nctrl->max_segments = ctrl->dev->ops->max_segments;
+
+	/* Init queues */
+
+	/* Call nvme_init_ctrl */
+
+	rc = ctrl->dev->ops->setup_ctrl(ctrl, true);
+	if (rc)
+		goto out_module_put;

+
+	rc = nvme_tcp_ofld_setup_ctrl(nctrl, true);
+	if (rc)
+		goto out_uninit_ctrl;

+
+	return nctrl;
+
+out_uninit_ctrl:
+	ctrl->dev->ops->release_ctrl(ctrl);
+out_module_put:
+	module_put(dev->ops->module);
+out_free_ctrl:
+	kfree(ctrl);
+
+	return ERR_PTR(rc);
+}
+
  static struct nvmf_transport_ops nvme_tcp_ofld_transport = {
  	.name		= "tcp_offload",
  	.module		= THIS_MODULE,

@@ -107,6 +200,7 @@ static struct nvmf_transport_ops nvme_tcp_ofld_transport = {
  			  NVMF_OPT_RECONNECT_DELAY | NVMF_OPT_HDR_DIGEST |
  			  NVMF_OPT_DATA_DIGEST | NVMF_OPT_NR_POLL_QUEUES |
  			  NVMF_OPT_TOS,
+	.create_ctrl	= nvme_tcp_ofld_create_ctrl,
  };
  
  static int __init nvme_tcp_ofld_init_module(void)