Re: [PATCH 1/4] scsi: Fix can_queue comments

[John Garry <john.g.garry@oracle.com>]

On 17/04/2026 23:57, Mike Christie wrote:
> The Scsi_Host can_queue comment assumes the old pre-mq can_queue use or
> it assumed host_tagset is set. This syncs the scsi_host_template and
> Scsi_Host comment so they are in sync.
> 
> It also redirects the nr_hw_queues comment to can_queue so we only
> have to describe how can_queue and nr_hw_queues are related in one
> place.
> 
> I also dropped the non-interrupt vs interrupt driven comment because it
> doesn't seem to apply anymore.
> 
> Signed-off-by: Mike Christie <michael.christie@oracle.com>

Regardless of some nitpicking:
Reviewed-by: John Garry <john.g.garry@oracle.com>

> ---
>   include/scsi/scsi_host.h | 21 +++++++++------------
>   1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
> index f6e12565a81d..7c747b566bc3 100644
> --- a/include/scsi/scsi_host.h
> +++ b/include/scsi/scsi_host.h
> @@ -381,10 +381,13 @@ struct scsi_host_template {
>   	const char *proc_name;
>   
>   	/*
> -	 * This determines if we will use a non-interrupt driven
> -	 * or an interrupt driven scheme.  It is set to the maximum number
> -	 * of simultaneous commands a single hw queue in HBA will accept
> -	 * excluding internal commands.
> +	 * If host_tagset is set, this is the maximum number of simultaneous
> +	 * commands the host will accept excluding internal commands.

nit: I'd have "... simultaneous commands the host will accept excluding 
internal commands over all HW queues".

> +	 *
> +	 * If host_tagset is not set, this is the maximum number simultaneous
> +	 * commands a single hw queue in the host will accept excluding
> +	 * internal commands. In other words, the total queue depth per host
> +	 * is nr_hw_queues * can_queue.
>   	 */
>   	int can_queue;
>   
> @@ -631,10 +634,7 @@ struct Scsi_Host {
>   
>   	int this_id;
>   
> -	/*
> -	 * Number of commands this host can handle at the same time.
> -	 * This excludes reserved commands as specified by nr_reserved_cmds.
> -	 */
> +	/* See scsi_host_template's can_queue. */
>   	int can_queue;
>   	/*
>   	 * Number of reserved commands to allocate, if any.
> @@ -653,10 +653,7 @@ struct Scsi_Host {
>   	/*
>   	 * In scsi-mq mode, the number of hardware queues supported by the LLD.

I think that this scsi-mq comment can be removed or fixed, as we have 
not had a separate mq mode in some time. I can do that as a separate 
change if you like.

>   	 *
> -	 * Note: it is assumed that each hardware queue has a queue depth of
> -	 * can_queue. In other words, the total queue depth per host
> -	 * is nr_hw_queues * can_queue. However, for when host_tagset is set,
> -	 * the total queue depth is can_queue.
> +	 * See scsi_host_template's can_queue for queueing requirements.

nit: I am not sure if we even need to mention this. By default, people 
would or should reference scsi_host_template

>   	 */
>   	unsigned nr_hw_queues;
>   	unsigned nr_maps;