Re: [PATCH V3 1/3] nvmet: make ctrl-id configurable

[Christoph Hellwig <hch@lst.de>]

On Wed, Nov 27, 2019 at 01:40:32AM -0800, Chaitanya Kulkarni wrote:
> +	int ret = -EINVAL;
> +	u16 cntlid_min;
> +
> +	if (sscanf(page, "%hu\n", &cntlid_min) != 1)
> +		return ret;
> +
> +	if (cntlid_min == 0) {
> +		pr_info("specified cntlid_min = 0 is not allowed\n");
> +		return ret;
> +	}
> +
> +	down_write(&nvmet_config_sem);
> +	if (cntlid_min >= to_subsys(item)->cntlid_max) {
> +		pr_info("specified cntlid_min is >= current cntlid_max\n");
> +		goto out;

I'm not sure we need the pr_info calls here.  The error conditions
are pretty clear when we get an -EINVAL from the write.

> +	}
> +
> +	ret = 0;
> +	to_subsys(item)->cntlid_min = cntlid_min;
> +out:
> +	up_write(&nvmet_config_sem);
> +
> +	return ret ? ret : cnt;

The tail of the function could be simplified by avoid the ret variable.
the ret variable:

	down_write(&nvmet_config_sem);
	if (cntlid_min >= to_subsys(item)->cntlid_max)
		goto out_unlock;
	to_subsys(item)->cntlid_min = cntlid_min;
	up_write(&nvmet_config_sem);
	return cnt;

out_unlock:
	up_write(&nvmet_config_sem);
	return -EINVAL;


> +	if (cntlid_max == 0) {
> +		pr_info("specified cntlid_max = 0 is not allowed\n");
> +		return ret;
> +	}
> +
> +	down_write(&nvmet_config_sem);
> +	if (cntlid_max <= to_subsys(item)->cntlid_min) {
> +		pr_info("specified cntlid_max is <= current cntlid_min\n");
> +		goto out;
> +	}
> +
> +	ret = 0;
> +	to_subsys(item)->cntlid_max = cntlid_max;
> +out:
> +	up_write(&nvmet_config_sem);
> +
> +	return ret ? ret : cnt;

Same comments here.

>  	}
> -
> +	subsys->cntlid_min = NVME_CNTLID_MIN;
> +	subsys->cntlid_max = NVME_CNTLID_MAX;
>  	kref_init(&subsys->ref);
>  
>  	mutex_init(&subsys->lock);
> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> index 46df45e837c9..6492d12e626a 100644
> --- a/drivers/nvme/target/nvmet.h
> +++ b/drivers/nvme/target/nvmet.h
> @@ -211,6 +211,8 @@ struct nvmet_subsys {
>  	struct list_head	namespaces;
>  	unsigned int		nr_namespaces;
>  	unsigned int		max_nsid;
> +	u16			cntlid_min;
> +	u16			cntlid_max;
>  
>  	struct list_head	ctrls;
>  
> -- 
> 2.22.1
---end quoted text---

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