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

[Andy Lutomirski]

On Feb 2, 2016 5:37 AM, "Corey Minyard" <minyard@xxxxxxx> wrote:
>
> 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 Ã 16:43 -0600, minyard@xxxxxxx a Ãcrit :
>>>
>>> From: Corey Minyard <cminyard@xxxxxxxxxx>
>>>
>>> This is so that an IPMI platform device can be created from a
>>> DMI firmware entry.
>>>
>>> Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
>>> Cc: Jean Delvare <jdelvare@xxxxxxx>
>>> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
>>> ---
>>>   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.

I think dmi_device is right, especially if your patches result in a
firmware_node sysfs link being created.  That way the link will point
to the right place.


--Andy