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Date:   Sun, 30 Jul 2023 09:35:40 +0200
From:   Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas@t-8ch.de>
To:     Armin Wolf <W_Armin@gmx.de>
Cc:     hdegoede@redhat.com, markgross@kernel.org,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] platform/x86: wmi-bmof: Simplify read_bmof()
Message-ID: <099d2ef4-76d3-4b9f-9264-22ad8437eb5b@t-8ch.de>
References: <20230730043817.12888-1-W_Armin@gmx.de>
 <20230730043817.12888-2-W_Armin@gmx.de>
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On 2023-07-30 06:38:16+0200, Armin Wolf wrote:
> Replace offset handling code with a single call
> to memory_read_from_buffer() to simplify read_bmof().
> 
> Tested on a ASUS PRIME B650-PLUS.
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  drivers/platform/x86/wmi-bmof.c | 22 +++++-----------------
>  1 file changed, 5 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/platform/x86/wmi-bmof.c b/drivers/platform/x86/wmi-bmof.c
> index d0516cacfcb5..644d2fd889c0 100644
> --- a/drivers/platform/x86/wmi-bmof.c
> +++ b/drivers/platform/x86/wmi-bmof.c
> @@ -25,25 +25,13 @@ struct bmof_priv {
>  	struct bin_attribute bmof_bin_attr;
>  };
> 
> -static ssize_t
> -read_bmof(struct file *filp, struct kobject *kobj,
> -	 struct bin_attribute *attr,
> -	 char *buf, loff_t off, size_t count)
> +static ssize_t read_bmof(struct file *filp, struct kobject *kobj, struct bin_attribute *attr,
> +			 char *buf, loff_t off, size_t count)
>  {
> -	struct bmof_priv *priv =
> -		container_of(attr, struct bmof_priv, bmof_bin_attr);
> +	struct bmof_priv *priv = container_of(attr, struct bmof_priv, bmof_bin_attr);
> 
> -	if (off < 0)
> -		return -EINVAL;
> -
> -	if (off >= priv->bmofdata->buffer.length)
> -		return 0;
> -
> -	if (count > priv->bmofdata->buffer.length - off)
> -		count = priv->bmofdata->buffer.length - off;
> -
> -	memcpy(buf, priv->bmofdata->buffer.pointer + off, count);
> -	return count;
> +	return memory_read_from_buffer(buf, count, &off, priv->bmofdata->buffer.pointer,
> +				       priv->bmofdata->buffer.length);

Note: sysfs_kf_bin_read() seems also to be doing most of this validation.
So the invalid input values, expect for negative "off", can't happen anyways.
memory_read_from_buffer() is still nice though.

>  }
> 
>  static int wmi_bmof_probe(struct wmi_device *wdev, const void *context)
> --
> 2.39.2
>