Re: [PATCH v4 0/6] arch_topology: Build cacheinfo from primary CPU

[Pierre Gondois <pierre.gondois@arm.com>]

On 1/18/23 13:07, Sudeep Holla wrote:
> On Wed, Jan 18, 2023 at 11:55:59AM +0000, Sudeep Holla wrote:
>> On Wed, 4 Jan 2023 19:30:23 +0100, Pierre Gondois wrote:
>>> v2:
>>>   - Applied renaming/formatting comments from v1.
>>>   - Check CACHE_TYPE_VALID flag in pppt.c.
>>> v3:
>>>   - Applied Sudeep's suggestions (for patch 5/5):
>>>     - Renaming allocate_cache_info() -> fecth_cache_info()
>>>     - Updated error message
>>>     - Extract an inline allocate_cache_info() function
>>>   - Re-run checkpatch with --strict option
>>> v4:
>>>   - Remove RISC-V's implementation of init_cache_level() as not
>>>     necessary.
>>>   - Add patch: 'cacheinfo: Check 'cache-unified' property to count
>>>     cache leaves' to increase the number of leaves at a cache level
>>>     when no cache-size property is found.
>>>   - In cacheinfo: Use RISC-V's init_cache_level() [...],
>>>     make 'levels', 'leaves' and 'level' unsigned int to match
>>>     of_property_read_u32()'s parameters signedness.
>>>
>>> [...]
>>
>> Applied to sudeep.holla/linux (for-next/cacheinfo), thanks!
>>
> 
> I pushed the changes and then noticed some build warning report by
> kbuild posted only to you and one list(missing this list). Please post the
> fix if required on top of my for-next/cacheinfo so that it can be added
> on the top. Sorry for missing that.
> 

Hi Sudeep,
I think the reported issue can be ignored, the 'levels' and 'split_levels'
variables are initialized when used. If necessary, it is straightforward
to fix the warning.
Regards,
Pierre


The reported issue:
--- Start ---

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

    drivers/base/cacheinfo.c: In function 'fetch_cache_info':
>> drivers/base/cacheinfo.c:440:50: warning: 'levels' is used uninitialized [-Wuninitialized]
      440 |                 this_cpu_ci->num_leaves = levels + split_levels;
          |                                           ~~~~~~~^~~~~~~~~~~~~~
    drivers/base/cacheinfo.c:420:22: note: 'levels' was declared here
      420 |         unsigned int levels, split_levels;
          |                      ^~~~~~
>> drivers/base/cacheinfo.c:440:50: warning: 'split_levels' is used uninitialized [-Wuninitialized]
      440 |                 this_cpu_ci->num_leaves = levels + split_levels;
          |                                           ~~~~~~~^~~~~~~~~~~~~~
    drivers/base/cacheinfo.c:420:30: note: 'split_levels' was declared here
      420 |         unsigned int levels, split_levels;
          |                              ^~~~~~~~~~~~


vim +/levels +440 drivers/base/cacheinfo.c

    416	
    417	int fetch_cache_info(unsigned int cpu)
    418	{
    419		struct cpu_cacheinfo *this_cpu_ci;
    420		unsigned int levels, split_levels;
    421		int ret;
    422	
    423		if (acpi_disabled) {
    424			ret = init_of_cache_level(cpu);
    425			if (ret < 0)
    426				return ret;
    427		} else {
    428			ret = acpi_get_cache_info(cpu, &levels, &split_levels);
    429			if (ret < 0)
    430				return ret;
    431	
    432			this_cpu_ci = get_cpu_cacheinfo(cpu);
    433			this_cpu_ci->num_levels = levels;
    434			/*
    435			 * This assumes that:
    436			 * - there cannot be any split caches (data/instruction)
    437			 *   above a unified cache
    438			 * - data/instruction caches come by pair
    439			 */
  > 440			this_cpu_ci->num_leaves = levels + split_levels;
    441		}
    442		if (!cache_leaves(cpu))
    443			return -ENOENT;
    444	
    445		return allocate_cache_info(cpu);
    446	}
    447	

--- End ---

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