Re: [PATCH 2/3] of/numa: fix a memory@ dt node can only contains one memory block

[Leizhen (ThunderTown)]

On 2016/5/27 12:20, Rob Herring wrote:
> On Thu, May 26, 2016 at 10:36 PM, Leizhen (ThunderTown)
> <thunder.leizhen@xxxxxxxxxx> wrote:
>>
>>
>> On 2016/5/26 21:13, Rob Herring wrote:
>>> On Thu, May 26, 2016 at 10:43:58AM +0800, Zhen Lei wrote:
>>>> For a normal memory@ devicetree node, its reg property can contains more
>>>> memory blocks.
>>>>
>>>> Because we don't known how many memory blocks maybe contained, so we try
>>>> from index=0, increase 1 until error returned(the end).
>>>>
>>>> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
>>>> ---
>>>>  drivers/of/of_numa.c | 30 ++++++++++++++++++++----------
>>>>  1 file changed, 20 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/of/of_numa.c b/drivers/of/of_numa.c
>>>> index 21d831f..2c5f249 100644
>>>> --- a/drivers/of/of_numa.c
>>>> +++ b/drivers/of/of_numa.c
>>>> @@ -63,7 +63,7 @@ static int __init of_numa_parse_memory_nodes(void)
>>>>      struct device_node *np = NULL;
>>>>      struct resource rsrc;
>>>>      u32 nid;
>>>> -    int r = 0;
>>>> +    int i, r = 0;
>>>>
>>>>      for (;;) {
>>>>              np = of_find_node_by_type(np, "memory");
>>>> @@ -82,17 +82,27 @@ static int __init of_numa_parse_memory_nodes(void)
>>>>                      /* some other error */
>>>>                      break;
>>>>
>>>> -            r = of_address_to_resource(np, 0, &rsrc);
>>>> -            if (r) {
>>>> -                    pr_err("NUMA: bad reg property in memory node\n");
>>>> -                    break;
>>>> +            for (i = 0; ; i++) {
>>>> +                    r = of_address_to_resource(np, i, &rsrc);
>>>> +                    if (r) {
>>>> +                            /* reached the end of of_address */
>>>> +                            if (i > 0) {
>>>> +                                    r = 0;
>>>> +                                    break;
>>>> +                            }
>>>> +
>>>> +                            pr_err("NUMA: bad reg property in memory node\n");
>>>> +                            goto finished;
>>>> +                    }
>>>> +
>>>> +                    r = numa_add_memblk(nid, rsrc.start,
>>>> +                                        rsrc.end - rsrc.start + 1);
>>>> +                    if (r)
>>>> +                            goto finished;
>>>>              }
>>>> -
>>>> -            r = numa_add_memblk(nid, rsrc.start,
>>>> -                                rsrc.end - rsrc.start + 1);
>>>> -            if (r)
>>>> -                    break;
>>>>      }
>>>> +
>>>> +finished:
>>>>      of_node_put(np);
>>>
>>> This function can be simplified down to:
>>>
>>>       for_each_node_by_type(np, "memory") {
>> OK, That's good.
>>
>>>               r = of_property_read_u32(np, "numa-node-id", &nid);
>>>               if (r == -EINVAL)
>>>                       /*
>>>                        * property doesn't exist if -EINVAL, continue
>>>                        * looking for more memory nodes with
>>>                        * "numa-node-id" property
>>>                        */
>>>                       continue;
>> Hi, everybody:
>>     If some "memory" node contains "numa-node-id", but some others missed. Can we simply ignored it?
>> I think we should break out too, and faking to only have node0.
> 
> Continuing to work is probably better than not.
> 
>>
>>>               else if (r)
>>>                       /* some other error */
>>>                       break;
>>>
>>>               r = of_address_to_resource(np, 0, &rsrc);
>>>               for (i = 0; !r; i++, r = of_address_to_resource(np, i,
>>
>> But r(non-zero) is just break this loop, the original is break the outer for (;;) loop
> 
> It is not really the kernel's job to validate the DT. If there's
> random things in it then kernel's behavior is undefined.
> 
>>
>> How about as below?
>>
>>         for_each_node_by_type(np, "memory") {
>>                 ... ...
>>
>>                 for (i = 0; !of_address_to_resource(np, i, &rsrc); i++) {
>>                         r = numa_add_memblk(nid, rsrc.start,
>>                                             rsrc.end - rsrc.start + 1);
>>                         if (r)
>>                                 goto finished;
>>                 }
>>
>>                 if (!i)
>>                         pr_err("NUMA: bad reg property in memory node\n");
>>         }
>>
>> finished:
> 
> Please try to avoid the goto. You can check r in the outer loop too.

OK. I have rewritten this function according to your advice.

	for_each_node_by_type(np, "memory") {
                r = of_property_read_u32(np, "numa-node-id", &nid);
                if (r == -EINVAL)
                        /*
                         * property doesn't exist if -EINVAL, continue
                         * looking for more memory nodes with
                         * "numa-node-id" property
                         */
                        continue;
									//I deleted the break of "some other error", and it will break in below "if (!i || r)" branch

                for (i = 0; !r && !of_address_to_resource(np, i, &rsrc); i++)
                        r = numa_add_memblk(nid, rsrc.start,
                                            rsrc.end - rsrc.start + 1);

                if (!i || r) {
                        of_node_put(np);				//I moved here, so that it looks more clear. Because in the normal use of for_each_node_by_type, of_node_put is not required
                        pr_err("NUMA: bad property in memory node\n");	//Deleted "reg", so that it's suitable or harmless for other error cases
                        break;
                }
        }

	return r;

> 
> Rob
> 
> .
>