linux-kernel - Re: [PATCH V7 1/8] ACPI: I/O Remapping Table (IORT) initial support

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Message-ID: <576A7E98.4060502@arm.com>
Date:	Wed, 22 Jun 2016 13:03:36 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Tomasz Nowicki <tn@...ihalf.com>,
	Hanjun Guo <hanjun.guo@...aro.org>, tglx@...utronix.de,
	jason@...edaemon.net, rjw@...ysocki.net, bhelgaas@...gle.com,
	lorenzo.pieralisi@....com, robert.richter@...iumnetworks.com,
	shijie.huang@....com, Suravee.Suthikulpanit@....com
Cc:	al.stone@...aro.org, mw@...ihalf.com, graeme.gregory@...aro.org,
	Catalin.Marinas@....com, will.deacon@....com,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, ddaney.cavm@...il.com,
	okaya@...eaurora.org, andrea.gallo@...aro.org,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH V7 1/8] ACPI: I/O Remapping Table (IORT) initial support

On 22/06/16 12:06, Tomasz Nowicki wrote:
> On 22.06.2016 12:50, Marc Zyngier wrote:
>> On 21/06/16 08:12, Hanjun Guo wrote:
>>> Hi Tomasz,
>>>
>>> Sorry for jumping out late, just one comment below.
>>>
>>> On 2016/6/20 19:02, Tomasz Nowicki wrote:
>>>> IORT shows representation of IO topology for ARM based systems.
>>>> It describes how various components are connected together on
>>>> parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec.
>>>>
>>>> Initial support allows to detect IORT table presence and save its
>>>> root pointer obtained through acpi_get_table(). The pointer validity
>>>> depends on acpi_gbl_permanent_mmap because if acpi_gbl_permanent_mmap
>>>> is not set while using IORT nodes we would dereference unmapped pointers.
>>>>
>>>> For the aforementioned reason call iort_table_detect() from acpi_init()
>>>> which guarantees acpi_gbl_permanent_mmap to be set at that point.
>>>>
>>>> Add generic helpers which are helpful for scanning and retrieving
>>>> information from IORT table content. List of the most important helpers:
>>>> - iort_find_dev_node() finds IORT node for a given device
>>>> - iort_node_map_rid() maps device RID and returns IORT node which provides
>>>>    final translation
>>>>
>>>> Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
>>>> ---
>>>>   drivers/acpi/Kconfig  |   3 +
>>>>   drivers/acpi/Makefile |   1 +
>>>>   drivers/acpi/bus.c    |   2 +
>>>>   drivers/acpi/iort.c   | 220 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>>>   include/linux/iort.h  |  30 +++++++
>>>
>>> [...]
>>>
>>>> +static acpi_status
>>>> +iort_match_node_callback(struct acpi_iort_node *node, void *context)
>>>> +{
>>>> +	struct device *dev = context;
>>>> +
>>>> +	switch (node->type) {
>>>> +	case ACPI_IORT_NODE_NAMED_COMPONENT: {
>>>> +		struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>>>
>>> ACPI_ALLOCATE_BUFFER is used here, so ...
>>>
>>>> +		struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
>>>> +		struct acpi_iort_named_component *ncomp;
>>>> +
>>>> +		if (!adev)
>>>> +			break;
>>>> +
>>>> +		ncomp = (struct acpi_iort_named_component *)node->node_data;
>>>> +
>>>> +		if (ACPI_FAILURE(acpi_get_name(adev->handle,
>>>> +					       ACPI_FULL_PATHNAME, &buffer))) {
>>>> +			dev_warn(dev, "Can't get device full path name\n");
>>>> +			break;
>>>> +		}
>>>> +
>>>> +		if (!strcmp(ncomp->device_name, (char *)buffer.pointer))
>>>> +			return AE_OK;
>>>
>>> ... we need to kfree(buffer.pointer) before we return or break.
>>
>> For the record, I've queued this patch on top:
>>
>> diff --git a/drivers/acpi/iort.c b/drivers/acpi/iort.c
>> index 496dcf6..3b9e55b 100644
>> --- a/drivers/acpi/iort.c
>> +++ b/drivers/acpi/iort.c
>> @@ -158,11 +158,15 @@ iort_match_node_callback(struct acpi_iort_node *node, void *context)
>>   		if (ACPI_FAILURE(acpi_get_name(adev->handle,
>>   					       ACPI_FULL_PATHNAME, &buffer))) {
>>   			dev_warn(dev, "Can't get device full path name\n");
>> -			break;
>> -		}
>> +		} else {
>> +			int match;
>>
>> -		if (!strcmp(ncomp->device_name, (char *)buffer.pointer))
>> -			return AE_OK;
>> +			match = !strcmp(ncomp->device_name, buffer.pointer);
>> +			acpi_os_free(&buffer);
>> +
>> +			if (match)
>> +				return AE_OK;
>> +		}
>>
>>   		break;
>>   	}
>>
>>
>> assuming that Rafael is OK with the general approach, of course.
>>
> 
> Thanks Marc. As Lorenzo pointed out, we need another fix for 
> iort_node_map_rid(). Do you want me to refresh the whole series or this 
> patch only?

If the changes are localized enough, just this patch.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...