netdev - Re: [PATCH net-next v2 11/17] ethernet: ucc_geth: don't statically allocate eight ucc_geth

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Message-ID: <fa391dc7-9870-dd7b-503d-c0f1468328c2@csgroup.eu>
Date:   Wed, 20 Jan 2021 08:02:46 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        netdev@...r.kernel.org
Cc:     Li Yang <leoyang.li@....com>,
        "David S . Miller" <davem@...emloft.net>,
        Zhao Qiang <qiang.zhao@....com>, Andrew Lunn <andrew@...n.ch>,
        Jakub Kicinski <kuba@...nel.org>,
        Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
Subject: Re: [PATCH net-next v2 11/17] ethernet: ucc_geth: don't statically
 allocate eight ucc_geth_info



Le 19/01/2021 à 16:07, 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 65ef7ae38912..67b93d60243e 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)
>   {
> @@ -3715,25 +3713,23 @@ 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);

What about using devm_kmalloc() and avoid those kfree and associated goto ?


> +	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);