linux-kernel - Re: [PATCH net-next] iavf: Avoid a memory allocation in iavf_print_link

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Message-ID: <ba7040d4-337f-56a1-0f87-cc6dd70228ec@intel.com>
Date:   Mon, 25 Sep 2023 10:11:22 +0200
From:   Przemek Kitszel <przemyslaw.kitszel@...el.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
CC:     <linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>,
        <intel-wired-lan@...ts.osuosl.org>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] iavf: Avoid a memory allocation in
 iavf_print_link_message()

On 9/23/23 14:17, Christophe JAILLET wrote:
> IAVF_MAX_SPEED_STRLEN is only 13 and 'speed' is allocated and freed within
> iavf_print_link_message().
> 
> 'speed' is only used with some snprintf() and netdev_info() calls.
> 
> So there is no real use to kzalloc()/free() it. Use the stack instead.
> This saves a memory allocation.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>   drivers/net/ethernet/intel/iavf/iavf_virtchnl.c | 7 +------
>   1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
> index 8ce6389b5815..980dc69d7fbe 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
> @@ -1389,18 +1389,14 @@ void iavf_disable_vlan_insertion_v2(struct iavf_adapter *adapter, u16 tpid)
>   static void iavf_print_link_message(struct iavf_adapter *adapter)
>   {
>   	struct net_device *netdev = adapter->netdev;
> +	char speed[IAVF_MAX_SPEED_STRLEN];
>   	int link_speed_mbps;
> -	char *speed;
>   
>   	if (!adapter->link_up) {
>   		netdev_info(netdev, "NIC Link is Down\n");
>   		return;
>   	}
>   
> -	speed = kzalloc(IAVF_MAX_SPEED_STRLEN, GFP_KERNEL);
> -	if (!speed)
> -		return;
> -
>   	if (ADV_LINK_SUPPORT(adapter)) {
>   		link_speed_mbps = adapter->link_speed_mbps;
>   		goto print_link_msg;
> @@ -1452,7 +1448,6 @@ static void iavf_print_link_message(struct iavf_adapter *adapter)
>   	}
>   
>   	netdev_info(netdev, "NIC Link is Up Speed is %s Full Duplex\n", speed);
> -	kfree(speed);
>   }
>   
>   /**

Looks fine, thanks!
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>

I know that Jesse is fixing snprintf() calls currently,
but I bet it's not conflicting.