netdev - Re: [PATCH rdma-next v1 05/11] RDMA/counter: Add optional counter support

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Message-ID: <20210927170318.GB1529966@nvidia.com>
Date:   Mon, 27 Sep 2021 14:03:18 -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 05/11] RDMA/counter: Add optional counter
 support

On Wed, Sep 15, 2021 at 02:07:24AM +0300, Leon Romanovsky wrote:
>  
> +int rdma_counter_modify(struct ib_device *dev, u32 port, int index, bool enable)
> +{
> +	struct rdma_hw_stats *stats;
> +	int ret;
> +
> +	if (!dev->ops.modify_hw_stat)
> +		return -EOPNOTSUPP;
> +
> +	stats = ib_get_hw_stats_port(dev, port);
> +	if (!stats)
> +		return -EINVAL;
> +
> +	mutex_lock(&stats->lock);
> +	ret = dev->ops.modify_hw_stat(dev, port, index, enable);
> +	if (!ret)
> +		enable ? clear_bit(index, stats->is_disabled) :
> +			set_bit(index, stats->is_disabled);

This is not a kernel coding style write out the if, use success
oriented flow

Also, shouldn't this logic protect the driver from being called on
non-optional counters?

>  	for (i = 0; i < data->stats->num_counters; i++) {
> -		attr = &data->attrs[i];
> +		if (data->stats->descs[i].flags & IB_STAT_FLAG_OPTIONAL)
> +			continue;
> +		attr = &data->attrs[pos];
>  		sysfs_attr_init(&attr->attr.attr);
>  		attr->attr.attr.name = data->stats->descs[i].name;
>  		attr->attr.attr.mode = 0444;
>  		attr->attr.show = hw_stat_device_show;
>  		attr->show = show_hw_stats;
> -		data->group.attrs[i] = &attr->attr.attr;
> +		data->group.attrs[pos] = &attr->attr.attr;
> +		pos++;
>  	}

This isn't OK, the hw_stat_device_show() computes the stat index like
this:

	return stat_attr->show(ibdev, ibdev->hw_stats_data->stats,
			       stat_attr - ibdev->hw_stats_data->attrs, 0, buf);

Which assumes the stats are packed contiguously. This only works
because mlx5 is always putting the optional stats at the end.

>  /**
>   * struct rdma_stat_desc
>   * @name - The name of the counter
> - *
> + * @flags - Flags of the counter; For example, IB_STAT_FLAG_OPTIONAL
>   */

The previous patch shouldn't have had the extra blank line then?

  
> +int rdma_counter_modify(struct ib_device *dev, u32 port, int index,
> +			bool is_add);

index should be unsigned int

The bool is called 'is_add' here but the implementation is 'enable' ?

Jason