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

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Message-ID: <576A711D.5080206@semihalf.com>
Date:	Wed, 22 Jun 2016 13:06:05 +0200
From:	Tomasz Nowicki <tn@...ihalf.com>
To:	Marc Zyngier <marc.zyngier@....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 22.06.2016 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?

Tomasz