linux-kernel - Re: [PATCH v2] hv_netvsc: Allocate rx indirection table size dynamically

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Message-ID: <ZG8ao4SnUCyZO6jH@corigine.com>
Date:   Thu, 25 May 2023 10:21:55 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Shradha Gupta <shradhagupta@...ux.microsoft.com>
Cc:     linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Long Li <longli@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        "David S. Miller" <davem@...emloft.net>,
        Steen Hegelund <steen.hegelund@...rochip.com>
Subject: Re: [PATCH v2] hv_netvsc: Allocate rx indirection table size
 dynamically

On Wed, May 24, 2023 at 02:57:10AM -0700, Shradha Gupta wrote:
> Allocate the size of rx indirection table dynamically in netvsc
> from the value of size provided by OID_GEN_RECEIVE_SCALE_CAPABILITIES
> query instead of using a constant value of ITAB_NUM.
> 
> Signed-off-by: Shradha Gupta <shradhagupta@...ux.microsoft.com>

Hi Shradha,

thanks for your patch.

Some nits from my side.
And some friendly advice: please consider using checkpatch

...

> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index 0103ff914024..ab791e4ca63c 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -1040,6 +1040,13 @@ static int netvsc_detach(struct net_device *ndev,
>  
>  	rndis_filter_device_remove(hdev, nvdev);
>  
> +	/* 
> +	 * Free the rx indirection table and reset the table size to 0.
> +	 * With the netvsc_attach call it will get allocated again.
> +	 */

nit: In Networking code multi-line comments look like this:

	/* Free the rx indirection table and reset the table size to 0.
	 * With the netvsc_attach call it will get allocated again.
	 */

> +	ndev_ctx->rx_table_sz = 0;
> +	kfree(ndev_ctx->rx_table);
> +
>  	return 0;
>  }
>  

...

> @@ -1548,6 +1548,20 @@ struct netvsc_device *rndis_filter_device_add(struct hv_device *dev,
>  	if (ret || rsscap.num_recv_que < 2)
>  		goto out;
>  
> +	if (rsscap.num_indirect_tabent &&
> +	    rsscap.num_indirect_tabent <= ITAB_NUM_MAX)
> +		ndc->rx_table_sz = rsscap.num_indirect_tabent;
> +	else
> +		ndc->rx_table_sz = ITAB_NUM;
> +
> +	ndc->rx_table = kzalloc(sizeof(u16) * ndc->rx_table_sz,
> +				GFP_KERNEL);

nit: kcalloc seems appropriate here.

> +	if (!ndc->rx_table) {
> +		netdev_err(net, "Error in allocating rx indirection table of size %d\n",
> +				ndc->rx_table_sz);

nit: No need to log memory allocation errors, the mm core does that.

     Also, the alignment of the line above should match of the opening '('
     of the preceding line.

	f(a,
	  b);

> +		goto out;
> +	}
> +
>  	/* This guarantees that num_possible_rss_qs <= num_online_cpus */
>  	num_possible_rss_qs = min_t(u32, num_online_cpus(),