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

Sagi Grimberg
2021-05-21T22:22:23Z

On 5/19/21 4:13 AM, Shai Malin wrote:
> From: Dean Balandin <dbalandin@marvell.com>
>
> 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 <irusskikh@marvell.com>
> Signed-off-by: Dean Balandin <dbalandin@marvell.com>
> Signed-off-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> Signed-off-by: Omkar Kulkarni <okulkarni@marvell.com>
> Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
> Signed-off-by: Ariel Elior <aelior@marvell.com>
> Signed-off-by: Shai Malin <smalin@marvell.com>
> ---
> 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)) {

This means that every controller will take a long-lived reference on the
module? Why?

> + 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;

goto module_put without an explicit module_get is confusing.

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

ops->setup_ctrl and then call to nvme_tcp_ofld_setup_ctrl?
Looks weird, why are these separated?

> +
> + 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)
>