linux-kernel - Re: [PATCH v2 1/3] dell-wmi: Stop storing pointers to DMI tables

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Date:	Tue, 19 Jan 2016 10:28:46 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Jean Delvare <jdelvare@...e.de>
Cc:	Andy Lutomirski <luto@...nel.org>,
	Pali Rohár <pali.rohar@...il.com>,
	platform-driver-x86@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] dell-wmi: Stop storing pointers to DMI tables

On Tue, Jan 19, 2016 at 3:04 AM, Jean Delvare <jdelvare@...e.de> wrote:
> Hi Andy,
>
> One more thing I just noticed...
>
> On Mon, 18 Jan 2016 12:59:38 -0800, Andy Lutomirski wrote:
>> @@ -372,20 +390,26 @@ static int __init dell_wmi_input_setup(void)
>>       dell_wmi_input_dev->phys = "wmi/input0";
>>       dell_wmi_input_dev->id.bustype = BUS_HOST;
>>
>> -     if (dell_new_hk_type) {
>> -             const struct key_entry *keymap = dell_wmi_prepare_new_keymap();
>> -             if (!keymap) {
>> -                     err = -ENOMEM;
>> -                     goto err_free_dev;
>> -             }
>> +     err = dmi_walk(handle_dmi_entry, &dmi_results);
>> +     if (err)
>> +             goto err_free_dev;
>> (...)
>> @@ -431,7 +446,6 @@ static int __init dell_wmi_init(void)
>>               return -ENODEV;
>>       }
>>
>> -     dmi_walk(find_hk_type, NULL);
>>
>>       err = dell_wmi_input_setup();
>>       if (err)
>
> Before, in the absence of DMI support, the driver would load and assume
> the old hotkey interface. After your change, the driver will fail to
> load if DMI support is missing. This could, in theory, cause a
> regression (although I would be very surprised if even the oldest
> supported models don't implement DMI.)

I switched it from a failure to a pr_warn.

>
> If you want this patch to make it into stable, you probably should
> stick to the original behavior and move that change (if you still
> believe it is a good idea) to a separate patch, and at the same time
> make DELL_WMI either select or depend on DMI. Many other platform/x86
> drivers should do the same, BTW, but that's a separate topic.
>

I'm going to add a patch for that to the series, without Cc: stable.
I don't think it's a big enough deal to be worth -stable churn.

--Andy