linux-kernel - Re: [PATCH v9 06/17] platform/x86: wmi: Don't allow drivers to get each other's GUIDs

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Date:   Tue, 17 Oct 2017 21:00:43 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Mario Limonciello <mario.limonciello@...l.com>
Cc:     dvhart@...radead.org, Andy Shevchenko <andy.shevchenko@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        Andy Lutomirski <luto@...nel.org>, quasisec@...gle.com,
        rjw@...ysocki.net, mjg59@...gle.com, hch@....de,
        Greg KH <greg@...ah.com>, Alan Cox <gnomes@...rguk.ukuu.org.uk>
Subject: Re: [PATCH v9 06/17] platform/x86: wmi: Don't allow drivers to get
 each other's GUIDs

On Tuesday 17 October 2017 13:21:50 Mario Limonciello wrote:
> The only driver using this was dell-wmi, and it really was a hack.
> The driver was getting a data attribute from another driver and this
> type of action should not be encouraged.
> 
> Rather drivers that need to interact with one another should pass
> data back and forth via exported functions.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@...l.com>
> Reviewed-by: Edward O'Callaghan <quasisec@...gle.com>

Reviewed-by: Pali Rohár <pali.rohar@...il.com>

> ---
>  drivers/platform/x86/wmi.c | 17 -----------------
>  include/linux/wmi.h        |  4 ----
>  2 files changed, 21 deletions(-)
> 
> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> index 4d73a87c2ddf..bcb41c1c7f52 100644
> --- a/drivers/platform/x86/wmi.c
> +++ b/drivers/platform/x86/wmi.c
> @@ -368,23 +368,6 @@ union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance)
>  }
>  EXPORT_SYMBOL_GPL(wmidev_block_query);
>  
> -struct wmi_device *wmidev_get_other_guid(struct wmi_device *wdev,
> -					 const char *guid_string)
> -{
> -	struct wmi_block *this_wb = container_of(wdev, struct wmi_block, dev);
> -	struct wmi_block *other_wb;
> -
> -	if (!find_guid(guid_string, &other_wb))
> -		return NULL;
> -
> -	if (other_wb->acpi_device != this_wb->acpi_device)
> -		return NULL;
> -
> -	get_device(&other_wb->dev.dev);
> -	return &other_wb->dev;
> -}
> -EXPORT_SYMBOL_GPL(wmidev_get_other_guid);
> -
>  /**
>   * wmi_set_block - Write to a WMI block
>   * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
> diff --git a/include/linux/wmi.h b/include/linux/wmi.h
> index 2cd10c3b89e9..ddee427e0721 100644
> --- a/include/linux/wmi.h
> +++ b/include/linux/wmi.h
> @@ -36,10 +36,6 @@ extern acpi_status wmidev_evaluate_method(struct wmi_device *wdev,
>  extern union acpi_object *wmidev_block_query(struct wmi_device *wdev,
>  					     u8 instance);
>  
> -/* Gets another device on the same bus.  Caller must put_device the result. */
> -extern struct wmi_device *wmidev_get_other_guid(struct wmi_device *wdev,
> -						const char *guid_string);
> -
>  struct wmi_device_id {
>  	const char *guid_string;
>  };

-- 
Pali Rohár
pali.rohar@...il.com