linux-kernel - Re: [PATCH 14/20] ethernet: ucc_geth: don't statically allocate eight ucc_geth

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Date:   Tue, 8 Dec 2020 16:13:15 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        Li Yang <leoyang.li@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Vladimir Oltean <vladimir.oltean@....com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Zhao Qiang <qiang.zhao@....com>
Subject: Re: [PATCH 14/20] ethernet: ucc_geth: don't statically allocate eight
 ucc_geth_info



Le 05/12/2020 à 20:17, Rasmus Villemoes a écrit :
> struct ucc_geth_info is somewhat large, and on systems with only one
> or two UCC instances, that just wastes a few KB of memory. So
> allocate and populate a chunk of memory at probe time instead of
> initializing them all during driver init.
> 
> Note that the existing "ug_info == NULL" check was dead code, as the
> address of some static array element can obviously never be NULL.
> 
> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@...vas.dk>
> ---
>   drivers/net/ethernet/freescale/ucc_geth.c | 32 +++++++++--------------
>   1 file changed, 12 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c
> index a06744d8b4af..273342233bba 100644
> --- a/drivers/net/ethernet/freescale/ucc_geth.c
> +++ b/drivers/net/ethernet/freescale/ucc_geth.c
> @@ -157,8 +157,6 @@ static const struct ucc_geth_info ugeth_primary_info = {
>   	.riscRx = QE_RISC_ALLOCATION_RISC1_AND_RISC2,
>   };
>   
> -static struct ucc_geth_info ugeth_info[8];
> -
>   #ifdef DEBUG
>   static void mem_disp(u8 *addr, int size)
>   {
> @@ -3714,25 +3712,23 @@ static int ucc_geth_probe(struct platform_device* ofdev)
>   	if ((ucc_num < 0) || (ucc_num > 7))
>   		return -ENODEV;
>   
> -	ug_info = &ugeth_info[ucc_num];
> -	if (ug_info == NULL) {
> -		if (netif_msg_probe(&debug))
> -			pr_err("[%d] Missing additional data!\n", ucc_num);
> -		return -ENODEV;
> -	}
> +	ug_info = kmalloc(sizeof(*ug_info), GFP_KERNEL);

Could we use dev_kmalloc() instead, to avoid the freeing on the wait out and the err_free_info: path ?

> +	if (ug_info == NULL)
> +		return -ENOMEM;
> +	memcpy(ug_info, &ugeth_primary_info, sizeof(*ug_info));
>   
>   	ug_info->uf_info.ucc_num = ucc_num;
>   
>   	err = ucc_geth_parse_clock(np, "rx", &ug_info->uf_info.rx_clock);
>   	if (err)
> -		return err;
> +		goto err_free_info;
>   	err = ucc_geth_parse_clock(np, "tx", &ug_info->uf_info.tx_clock);
>   	if (err)
> -		return err;
> +		goto err_free_info;
>   
>   	err = of_address_to_resource(np, 0, &res);
>   	if (err)
> -		return -EINVAL;
> +		goto err_free_info;
>   
>   	ug_info->uf_info.regs = res.start;
>   	ug_info->uf_info.irq = irq_of_parse_and_map(np, 0);
> @@ -3745,7 +3741,7 @@ static int ucc_geth_probe(struct platform_device* ofdev)
>   		 */
>   		err = of_phy_register_fixed_link(np);
>   		if (err)
> -			return err;
> +			goto err_free_info;
>   		ug_info->phy_node = of_node_get(np);
>   	}
>   
> @@ -3876,6 +3872,8 @@ static int ucc_geth_probe(struct platform_device* ofdev)
>   		of_phy_deregister_fixed_link(np);
>   	of_node_put(ug_info->tbi_node);
>   	of_node_put(ug_info->phy_node);
> +err_free_info:
> +	kfree(ug_info);
>   
>   	return err;
>   }
> @@ -3886,6 +3884,7 @@ static int ucc_geth_remove(struct platform_device* ofdev)
>   	struct ucc_geth_private *ugeth = netdev_priv(dev);
>   	struct device_node *np = ofdev->dev.of_node;
>   
> +	kfree(ugeth->ug_info);
>   	ucc_geth_memclean(ugeth);
>   	if (of_phy_is_fixed_link(np))
>   		of_phy_deregister_fixed_link(np);
> @@ -3920,17 +3919,10 @@ static struct platform_driver ucc_geth_driver = {
>   
>   static int __init ucc_geth_init(void)
>   {
> -	int i, ret;
> -
>   	if (netif_msg_drv(&debug))
>   		pr_info(DRV_DESC "\n");
> -	for (i = 0; i < 8; i++)
> -		memcpy(&(ugeth_info[i]), &ugeth_primary_info,
> -		       sizeof(ugeth_primary_info));
> -
> -	ret = platform_driver_register(&ucc_geth_driver);
>   
> -	return ret;
> +	return platform_driver_register(&ucc_geth_driver);
>   }
>   
>   static void __exit ucc_geth_exit(void)
>