Re: [PATCH] hns3: work around stack size warning

[Arnd Bergmann]

On Mon, Jun 23, 2025, at 05:19, Jijie Shao wrote:
>> on 2025/6/12 23:33, Jakub Kicinski wrote:
>>
>
> *Hi Jakub, Arnd We have changed the impleament as your suggestion. Would 
> you please help check it ? If it's OK, we will rewrite the rest parts of 
> our debugfs code. Thanks! *

The conversion to seq_file looks good to me, this does address the
stack usage problems I was observing.
Thanks for cleaning this up!

> -    sprintf(result[j++], "%u", index);
> -    sprintf(result[j++], "%u", readl_relaxed(ring->tqp->io_base +
> -        HNS3_RING_TX_RING_BD_NUM_REG));
> +    seq_printf(s, "%-4u%6s", index, " ");
> +    seq_printf(s, "%-5u%3s",
> +           readl_relaxed(base + HNS3_RING_TX_RING_BD_NUM_REG), " ");

I'm not sure I understand the format string changes here, I did
not think they were necessary.

Are you doing this to keep the output the same as before, or are
you reformatting the contents for readability?

> +static int hns3_dbg_common_init_t1(struct hnae3_handle *handle, u32 
> cmd)
> +{
> +    struct device *dev = &handle->pdev->dev;
> +    struct dentry *entry_dir;
> +    read_func func = NULL;
> +
> +    switch (hns3_dbg_cmd[cmd].cmd) {
> +    case HNAE3_DBG_CMD_TX_QUEUE_INFO:
> +        func = hns3_dbg_tx_queue_info;
> +        break;
> +    default:
> +        return -EINVAL;
> +    }
> +
> +    entry_dir = hns3_dbg_dentry[hns3_dbg_cmd[cmd].dentry].dentry;
> +    debugfs_create_devm_seqfile(dev, hns3_dbg_cmd[cmd].name, entry_dir,
> +                    func);
> +
> +    return 0;

This will work fine as well, but I think you can do slightly better
by having your own file_operations with a read function based
on single_open() and your current hns3_dbg_read_cmd().

I don't think you gain anything from using debugfs_create_devm_seqfile()
since you use debugfs_remove_recursive() for cleaning it up anyway.

     Arnd