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[PATCH v3 1/2] nvme: add capability to connect to an administrative controller

Kamaljit Singh posted 2 patches 2 months, 2 weeks ago
There is a newer version of this series
[PATCH v3 1/2] nvme: add capability to connect to an administrative controller
Posted by Kamaljit Singh 2 months, 2 weeks ago 
Suggested-by: Niklas Cassel <cassel@kernel.org>

Add capability to connect to an administrative controller by
preventing ioq creation for admin-controllers.

* Add helper nvme_admin_ctrl() to check for an administrative controller
* Add helper nvme_override_prohibited_io_queues() to override queue_count
* Call nvme_override_prohibited_io_queues() from nvme_init_ctrl_finish()
  so it applies to nvme/tcp and nvme/rdma

Signed-off-by: Kamaljit Singh <kamaljit.singh1@wdc.com>
---
 drivers/nvme/host/core.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e533d791955d..105127638c31 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3149,6 +3149,21 @@ static inline bool nvme_discovery_ctrl(struct nvme_ctrl *ctrl)
 	return ctrl->opts && ctrl->opts->discovery_nqn;
 }
 
+static inline bool nvme_admin_ctrl(struct nvme_ctrl *ctrl)
+{
+	return ctrl->cntrltype == NVME_CTRL_ADMIN;
+}
+
+/*
+ * An admin controller has one admin queue, but no I/O queues.
+ * Override queue_count so it only creates an admin queue.
+ */
+static inline void nvme_override_prohibited_io_queues(struct nvme_ctrl *ctrl)
+{
+	if (nvme_admin_ctrl(ctrl))
+		ctrl->queue_count = 1;
+}
+
 static bool nvme_validate_cntlid(struct nvme_subsystem *subsys,
 		struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 {
@@ -3670,6 +3685,12 @@ int nvme_init_ctrl_finish(struct nvme_ctrl *ctrl, bool was_suspended)
 	if (ret)
 		return ret;
 
+	if (nvme_admin_ctrl(ctrl))
+		dev_dbg(ctrl->device,
+			"Subsystem %s is an administrative controller",
+			ctrl->subsys->subnqn);
+	nvme_override_prohibited_io_queues(ctrl);
+
 	ret = nvme_configure_apst(ctrl);
 	if (ret < 0)
 		return ret;
-- 
2.43.0
Re: [PATCH v3 1/2] nvme: add capability to connect to an administrative controller
Posted by Hannes Reinecke 2 months, 2 weeks ago 
On 7/18/25 02:14, Kamaljit Singh wrote:
> Suggested-by: Niklas Cassel <cassel@kernel.org>
> 
> Add capability to connect to an administrative controller by
> preventing ioq creation for admin-controllers.
> 
> * Add helper nvme_admin_ctrl() to check for an administrative controller
> * Add helper nvme_override_prohibited_io_queues() to override queue_count
> * Call nvme_override_prohibited_io_queues() from nvme_init_ctrl_finish()
>    so it applies to nvme/tcp and nvme/rdma
> 
> Signed-off-by: Kamaljit Singh <kamaljit.singh1@wdc.com>
> ---
>   drivers/nvme/host/core.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index e533d791955d..105127638c31 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -3149,6 +3149,21 @@ static inline bool nvme_discovery_ctrl(struct nvme_ctrl *ctrl)
>   	return ctrl->opts && ctrl->opts->discovery_nqn;
>   }
>   
> +static inline bool nvme_admin_ctrl(struct nvme_ctrl *ctrl)
> +{
> +	return ctrl->cntrltype == NVME_CTRL_ADMIN;
> +}
> +
> +/*
> + * An admin controller has one admin queue, but no I/O queues.
> + * Override queue_count so it only creates an admin queue.
> + */
> +static inline void nvme_override_prohibited_io_queues(struct nvme_ctrl *ctrl)
> +{
> +	if (nvme_admin_ctrl(ctrl))
> +		ctrl->queue_count = 1;
> +}
> +
>   static bool nvme_validate_cntlid(struct nvme_subsystem *subsys,
>   		struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
>   {
> @@ -3670,6 +3685,12 @@ int nvme_init_ctrl_finish(struct nvme_ctrl *ctrl, bool was_suspended)
>   	if (ret)
>   		return ret;
>   
> +	if (nvme_admin_ctrl(ctrl))
> +		dev_dbg(ctrl->device,
> +			"Subsystem %s is an administrative controller",
> +			ctrl->subsys->subnqn);
> +	nvme_override_prohibited_io_queues(ctrl);
> +
>   	ret = nvme_configure_apst(ctrl);
>   	if (ret < 0)
>   		return ret;

One wonders why this is done for admin controllers only; surely 
discovery controllers also don't support I/O queues, and should
therefore have the same setting?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
Re: [PATCH v3 1/2] nvme: add capability to connect to an administrative controller
Posted by Niklas Cassel 2 months, 2 weeks ago 
Hello Kamaljit,

I think that the patch looks good.

That said, the Suggested-by trailer should go together with all other
trailers at the end of the commit log, see e.g.:
https://git.kernel.org/pub/scm/linux/kernel/git/libata/linux.git/commit/?id=a4daf088a77323154514eb1f8626bbdf9329cfd4


Kind regards,
Niklas
Re: [PATCH v3 1/2] nvme: add capability to connect to an administrative controller
Posted by Damien Le Moal 2 months, 2 weeks ago 
On 2025/07/18 9:14, Kamaljit Singh wrote:
> Suggested-by: Niklas Cassel <cassel@kernel.org>
> 
> Add capability to connect to an administrative controller by
> preventing ioq creation for admin-controllers.
> 
> * Add helper nvme_admin_ctrl() to check for an administrative controller
> * Add helper nvme_override_prohibited_io_queues() to override queue_count
> * Call nvme_override_prohibited_io_queues() from nvme_init_ctrl_finish()
>   so it applies to nvme/tcp and nvme/rdma
> 
> Signed-off-by: Kamaljit Singh <kamaljit.singh1@wdc.com>
> ---
>  drivers/nvme/host/core.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index e533d791955d..105127638c31 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -3149,6 +3149,21 @@ static inline bool nvme_discovery_ctrl(struct nvme_ctrl *ctrl)
>  	return ctrl->opts && ctrl->opts->discovery_nqn;
>  }
>  
> +static inline bool nvme_admin_ctrl(struct nvme_ctrl *ctrl)
> +{
> +	return ctrl->cntrltype == NVME_CTRL_ADMIN;
> +}
> +
> +/*
> + * An admin controller has one admin queue, but no I/O queues.
> + * Override queue_count so it only creates an admin queue.
> + */
> +static inline void nvme_override_prohibited_io_queues(struct nvme_ctrl *ctrl)
> +{
> +	if (nvme_admin_ctrl(ctrl))
> +		ctrl->queue_count = 1;
> +}
> +
>  static bool nvme_validate_cntlid(struct nvme_subsystem *subsys,
>  		struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
>  {
> @@ -3670,6 +3685,12 @@ int nvme_init_ctrl_finish(struct nvme_ctrl *ctrl, bool was_suspended)
>  	if (ret)
>  		return ret;
>  
> +	if (nvme_admin_ctrl(ctrl))
> +		dev_dbg(ctrl->device,
> +			"Subsystem %s is an administrative controller",
> +			ctrl->subsys->subnqn);
> +	nvme_override_prohibited_io_queues(ctrl);

I do not think that this inline function is useful. Simply open-code it inside
the if above:

	if (nvme_admin_ctrl(ctrl)) {
		/*
		 * An admin controller has one admin queue, but no I/O queues.
		 * Override queue_count so it only creates an admin queue.
		 */
		dev_dbg(ctrl->device,
			"Subsystem %s is an administrative controller",
			ctrl->subsys->subnqn);
		ctrl->queue_count = 1;
	}

With this, feel free to add:

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

-- 
Damien Le Moal
Western Digital Research

Patchew 2.1-devel-b67e4c2

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