linux-kernel - Re: [PATCH 2/4] dmi: Add a DMI firmware node and handling

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Date:	Tue, 02 Feb 2016 07:37:05 -0600
From:	Corey Minyard <minyard@....org>
To:	Jean Delvare <jdelvare@...e.de>
Cc:	openipmi-developer@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
	Corey Minyard <cminyard@...sta.com>
Subject: Re: [PATCH 2/4] dmi: Add a DMI firmware node and handling

On 02/01/2016 03:25 AM, Jean Delvare wrote:
> Hi Corey,
>
> I won't comment on the IPMI side of this as this isn't my area. However
> I have a comment on the DMI part:
>
> Le Friday 29 January 2016 à 16:43 -0600, minyard@....org a écrit :
>> From: Corey Minyard <cminyard@...sta.com>
>>
>> This is so that an IPMI platform device can be created from a
>> DMI firmware entry.
>>
>> Signed-off-by: Corey Minyard <cminyard@...sta.com>
>> Cc: Jean Delvare <jdelvare@...e.de>
>> Cc: Andy Lutomirski <luto@...nel.org>
>> ---
>>   drivers/firmware/dmi_scan.c | 34 ++++++++++++++++++++++++----------
>>   include/linux/dmi.h         | 24 ++++++++++++++++++++++++
>>   include/linux/fwnode.h      |  1 +
>>   3 files changed, 49 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
>> index da471b2..13d9bca 100644
>> --- a/drivers/firmware/dmi_scan.c
>> +++ b/drivers/firmware/dmi_scan.c
>> @@ -41,6 +41,16 @@ static struct dmi_memdev_info {
>>   } *dmi_memdev;
>>   static int dmi_memdev_nr;
>>   
>> +static void *dmi_zalloc(unsigned len)
>> +{
>> +	void *ret = dmi_alloc(len);
>> +
>> +	if (ret)
>> +		memset(ret, 0, len);
>> +
>> +	return ret;
>> +}
>> +
>>   static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
>>   {
>>   	const u8 *bp = ((u8 *) dm) + dm->length;
>> @@ -242,6 +252,12 @@ static void __init dmi_save_type(const struct dmi_header *dm, int slot,
>> (...)
>> @@ -250,15 +266,14 @@ static void __init dmi_save_one_device(int type, const char *name)
>>   	if (dmi_find_device(type, name, NULL))
>>   		return;
>>   
>> -	dev = dmi_alloc(sizeof(*dev) + strlen(name) + 1);
>> +	dev = dmi_zalloc(sizeof(*dev) + strlen(name) + 1);
>>   	if (!dev)
>>   		return;
>>   
>>   	dev->type = type;
>>   	strcpy((char *)(dev + 1), name);
>>   	dev->name = (char *)(dev + 1);
>> -	dev->device_data = NULL;
> This change seems rather unrelated, and I'm not sure what purpose it
> serves. On ia64 and arm64 it is clearly redundant as dmi_alloc calls
> kzalloc directly. On x86_64, extend_brk is called instead (don't ask me
> why, I have no clue) but looking at the code I see that it does
> memset(ret, 0, size) as well so memory is also zeroed there. Which makes
> dmi_alloc the same as dmi_zalloc on all 3 architectures.
>
> So please revert this change. This will make your patch easier to
> review, too.
>
Ok.  I had assumed extend_break wasn't zeroing since there were all the 
NULL assignments,
I should have looked.

I was thinking about this, and the fwnode could just be added to the 
IPMI device.  I'm not
sure if you would prefer that over adding it to dmi_device.  The fwnode 
is in acpi_device,
and I was modelling these changes after that, but maybe that's not 
required here.

Thanks,

-corey