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

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Message-ID: <20210927172006.GC1529966@nvidia.com>
Date:   Mon, 27 Sep 2021 14:20:06 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Doug Ledford <dledford@...hat.com>,
        Aharon Landau <aharonl@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
        Gal Pressman <galpress@...zon.com>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, Maor Gottlieb <maorg@...dia.com>,
        Mark Zhang <markzhang@...dia.com>,
        Mike Marciniszyn <mike.marciniszyn@...nelisnetworks.com>,
        Mustafa Ismail <mustafa.ismail@...el.com>,
        Naresh Kumar PBS <nareshkumar.pbs@...adcom.com>,
        Neta Ostrovsky <netao@...dia.com>, netdev@...r.kernel.org,
        Potnuri Bharat Teja <bharat@...lsio.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Selvin Xavier <selvin.xavier@...adcom.com>,
        Shiraz Saleem <shiraz.saleem@...el.com>,
        Yishai Hadas <yishaih@...dia.com>,
        Zhu Yanjun <zyjzyj2000@...il.com>
Subject: Re: [PATCH rdma-next v1 07/11] RDMA/nldev: Allow optional-counter
 status configuration through RDMA netlink

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