Re: [PATCH] drivers/of: Fix depth for sub-tree blob in unflatten_dt_nodes()

[Gavin Shan <gwshan-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On Wed, Jun 08, 2016 at 11:53:26AM -0400, Rhyland Klein wrote:
>On 6/8/2016 2:50 AM, Gavin Shan wrote:
>> The function is unflattening device sub-tree blob if @dad passed to
>> the function is valid. Currently, this functionality is used by PPC
>> PowerNV PCI hotplug driver only. There are possibly multiple nodes
>> in the first level of depth, fdt_next_node() bails immediately when
>> @depth becomes negative before the second device node can be probed
>> successfully. It leads to the device nodes except the first one won't
>> be unflattened successfully.
>> 
>> This fixes the issue by setting the initial depth (@inital_depth) to
>> 1 when this function is called to unflatten device sub-tree blob. No
>> logic changes when this function is used to unflatten non-sub-tree
>> blob.
>> 
>> Cc: Rhyland Klein <rklein-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> Fixes: 78c44d910 ("drivers/of: Fix depth when unflattening devicetree")
>> Signed-off-by: Gavin Shan <gwshan-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
>> ---
>>  drivers/of/fdt.c | 15 +++++++++++++--
>>  1 file changed, 13 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index 14f2f8c..9d70316 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -395,7 +395,7 @@ static int unflatten_dt_nodes(const void *blob,
>>  			      struct device_node **nodepp)
>>  {
>>  	struct device_node *root;
>> -	int offset = 0, depth = 0;
>> +	int offset = 0, depth = 0, initial_depth = 0;
>>  #define FDT_MAX_DEPTH	64
>>  	unsigned int fpsizes[FDT_MAX_DEPTH];
>>  	struct device_node *nps[FDT_MAX_DEPTH];
>> @@ -408,8 +408,19 @@ static int unflatten_dt_nodes(const void *blob,
>>  	root = dad;
>>  	fpsizes[depth] = dad ? strlen(of_node_full_name(dad)) : 0;
>>  	nps[depth] = dad;
>> +
>> +	/*
>> +	 * We're unflattening device sub-tree if @dad is valid. There are
>> +	 * possibly multiple nodes in the first level of depth. We need
>> +	 * set @depth to 1 to make fdt_next_node() happy as it bails
>> +	 * immediately when negative @depth is found. Otherwise, the device
>> +	 * nodes except the first one won't be unflattened successfully.
>> +	 */
>> +	if (dad)
>> +		depth = initial_depth = 1;
>> +
>>  	for (offset = 0;
>> -	     offset >= 0 && depth >= 0;
>> +	     offset >= 0 && depth >= initial_depth;
>>  	     offset = fdt_next_node(blob, offset, &depth)) {
>>  		if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH))
>>  			continue;
>> 
>
>I tested this and it seems to be working fine for me.
>
>Tested-by: Rhyland Klein <rklein-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>

Rhyland, thanks for your testing. I need send a v2 to adjust the @depth
before @fpsizes[depth] and @nps[depth] are initialized, which doesn't
affect your case and v2 should work for you. Your tested-by will be
included in v2.

Thanks,
Gavin

>-rhyland
>
>-- 
>nvpublic
>

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