linux-kernel - Re: [PATCH] net: hns3: reduce stack usage in hclge_dbg_dump_tm

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Message-ID: <5402aa8a-a20f-4d28-bd36-3b88702ea6ae@huawei.com>
Date:   Mon, 4 Dec 2023 16:31:59 +0800
From:   Jijie Shao <shaojijie@...wei.com>
To:     Arnd Bergmann <arnd@...nel.org>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
CC:     <shaojijie@...wei.com>, Arnd Bergmann <arnd@...db.de>,
        Hao Chen <chenhao418@...wei.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: hns3: reduce stack usage in hclge_dbg_dump_tm_pri()


on 2023/12/4 15:29, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
>
> @@ -981,7 +981,7 @@ static const struct hclge_dbg_item tm_pri_items[] = {
>   
>   static int hclge_dbg_dump_tm_pri(struct hclge_dev *hdev, char *buf, int len)
>   {
> -	char data_str[ARRAY_SIZE(tm_pri_items)][HCLGE_DBG_DATA_STR_LEN];
> +	char *data_str;
>   	struct hclge_tm_shaper_para c_shaper_para, p_shaper_para;
>   	char *result[ARRAY_SIZE(tm_pri_items)], *sch_mode_str;
>   	char content[HCLGE_DBG_TM_INFO_LEN];
> @@ -991,9 +991,13 @@ static int hclge_dbg_dump_tm_pri(struct hclge_dev *hdev, char *buf, int len)
>   	ret = hclge_tm_get_pri_num(hdev, &pri_num);
>   	if (ret)
>   		return ret;

Thanks,
  But it would be better if there is an empty line here.

> +	data_str = kcalloc(ARRAY_SIZE(tm_pri_items), HCLGE_DBG_DATA_STR_LEN,
> +			   GFP_KERNEL);
> +	if (!data_str)
> +		return -ENOMEM;
>   
>   	for (i = 0; i < ARRAY_SIZE(tm_pri_items); i++)
> -		result[i] = &data_str[i][0];
> +		result[i] = &data_str[i * HCLGE_DBG_DATA_STR_LEN];
>   
>   	hclge_dbg_fill_content(content, sizeof(content), tm_pri_items,
>   			       NULL, ARRAY_SIZE(tm_pri_items));
> @@ -1035,6 +1039,7 @@ static int hclge_dbg_dump_tm_pri(struct hclge_dev *hdev, char *buf, int len)
>   		pos += scnprintf(buf + pos, len - pos, "%s", content);
>   	}
>   

all exception condition also need to free memory before return. eg:
	for (i = 0; i < pri_num; i++) {
		ret = hclge_tm_get_pri_sch_mode(hdev, i, &sch_mode);
		if (ret)
			return ret;

		ret = hclge_tm_get_pri_weight(hdev, i, &weight);
		if (ret)
			return ret;

> +	kfree(data_str);
>   	return 0;
>   }
>