Subject: Re: [PATCH rdma-next v1 07/11] RDMA/nldev: Allow optional-counter status configuration through RDMA netlink

From: Jason Gunthorpe <[email-masked]>
Date: Mon, 27 Sep 2021 14:20:06 -0300

On Wed, Sep 15, 2021 at 02:07:26AM +0300, Leon Romanovsky wrote:
> -		return -EINVAL;
> +		need_enable = false;
> +		disabled = test_bit(i, stats->is_disabled);
> +		nla_for_each_nested(entry_attr,
> +				    tb[RDMA_NLDEV_ATTR_STAT_HWCOUNTERS], rem) {
> +			index = nla_get_u32(entry_attr);
> +			if (index >= stats->num_counters)
> +				return -EINVAL;
> +			if (i == index) {
> +				need_enable = true;
> +				break;
> +			}
> +		}
>  
> -	port = nla_get_u32(tb[RDMA_NLDEV_ATTR_PORT_INDEX]);
> -	if (!rdma_is_port_valid(device, port)) {
> -		ret = -EINVAL;
> -		goto err;
> +		if (disabled && need_enable)
> +			ret = rdma_counter_modify(device, port, i, true);
> +		else if (!disabled && !need_enable)
> +			ret = rdma_counter_modify(device, port, i, false);

This disabled check looks racy, I would do the no-change optimization inside
rdma_counter_modify()

Also, this is a O(N^2) algorithm, why not do it in one pass with a
small memory allocation for the target state bitmap?

Jason