Hi Lukasz,

I love your patch! Perhaps something to improve:

[auto build test WARNING on next-20200409]
[cannot apply to pm/linux-next tip/sched/core linus/master linux/master v5.6 
v5.6-rc7 v5.6-rc6 v5.6]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    
https://github.com/0day-ci/linux/commits/Lukasz-Luba/Add-support-for-devices-in-the-Energy-Model/20200410-172456
base:    873e37a44b1ee8ad4628ca257dc51c0c7c654326

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <l...@intel.com>


cppcheck warnings: (new ones prefixed by >>)

>> kernel/power/energy_model.c:394:15: warning: Variable 'ret' is assigned a 
>> value that is never used. [unreadVariable]
    int cpu, ret = 0;
                 ^

vim +/ret +394 kernel/power/energy_model.c

27871f7a8a341e Quentin Perret  2018-12-03  370  
27871f7a8a341e Quentin Perret  2018-12-03  371  /**
b4dc5cca354b8a Lukasz Luba     2020-04-10  372   * 
em_dev_register_perf_domain() - Register the Energy Model (EM) for a device
b4dc5cca354b8a Lukasz Luba     2020-04-10  373   * @dev         : Device for 
which the EM is to register
1ccc27ced21bf5 Lukasz Luba     2020-04-10  374   * @nr_states   : Number of 
performance states to register
27871f7a8a341e Quentin Perret  2018-12-03  375   * @cb          : Callback 
functions providing the data of the Energy Model
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  376   * @cpus        : Pointer to 
cpumask_t, which in case of a CPU device is
b4dc5cca354b8a Lukasz Luba     2020-04-10  377   *              obligatory. It 
can be taken from i.e. 'policy->cpus'. For other
b4dc5cca354b8a Lukasz Luba     2020-04-10  378   *              type of devices 
this should be set to NULL.
27871f7a8a341e Quentin Perret  2018-12-03  379   *
27871f7a8a341e Quentin Perret  2018-12-03  380   * Create Energy Model tables 
for a performance domain using the callbacks
27871f7a8a341e Quentin Perret  2018-12-03  381   * defined in cb.
27871f7a8a341e Quentin Perret  2018-12-03  382   *
27871f7a8a341e Quentin Perret  2018-12-03  383   * If multiple clients register 
the same performance domain, all but the first
27871f7a8a341e Quentin Perret  2018-12-03  384   * registration will be ignored.
27871f7a8a341e Quentin Perret  2018-12-03  385   *
27871f7a8a341e Quentin Perret  2018-12-03  386   * Return 0 on success
27871f7a8a341e Quentin Perret  2018-12-03  387   */
b4dc5cca354b8a Lukasz Luba     2020-04-10  388  int 
em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  389                                  
struct em_data_callback *cb, cpumask_t *cpus)
27871f7a8a341e Quentin Perret  2018-12-03  390  {
27871f7a8a341e Quentin Perret  2018-12-03  391          unsigned long cap, 
prev_cap = 0;
27871f7a8a341e Quentin Perret  2018-12-03  392          struct em_perf_domain 
*pd;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  393          struct em_device 
*em_dev;
27871f7a8a341e Quentin Perret  2018-12-03 @394          int cpu, ret = 0;
27871f7a8a341e Quentin Perret  2018-12-03  395  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  396          if (!dev || !nr_states 
|| !cb)
27871f7a8a341e Quentin Perret  2018-12-03  397                  return -EINVAL;
27871f7a8a341e Quentin Perret  2018-12-03  398  
27871f7a8a341e Quentin Perret  2018-12-03  399          /*
27871f7a8a341e Quentin Perret  2018-12-03  400           * Use a mutex to 
serialize the registration of performance domains and
27871f7a8a341e Quentin Perret  2018-12-03  401           * let the 
driver-defined callback functions sleep.
27871f7a8a341e Quentin Perret  2018-12-03  402           */
27871f7a8a341e Quentin Perret  2018-12-03  403          
mutex_lock(&em_pd_mutex);
27871f7a8a341e Quentin Perret  2018-12-03  404  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  405          em_dev = 
_em_dev_find_existing(dev);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  406          if (em_dev) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  407                  
mutex_unlock(&em_pd_mutex);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  408                  dev_dbg(dev, 
"EM: found exisiting pd%d\n", em_dev->id);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  409                  return -EEXIST;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  410          }
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  411  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  412          if 
(_is_cpu_device(dev)) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  413                  if (!cpus) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  414                          
mutex_unlock(&em_pd_mutex);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  415                          
dev_err(dev, "EM: invalid CPU mask\n");
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  416                          return 
-EINVAL;
27871f7a8a341e Quentin Perret  2018-12-03  417                  }
27871f7a8a341e Quentin Perret  2018-12-03  418  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  419                  /* Make sure we 
don't register domain for existing CPUs */
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  420                  if 
(em_cpus_pd_exist(cpus)) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  421                          
mutex_unlock(&em_pd_mutex);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  422                          return 
-EEXIST;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  423                  }
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  424  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  425                  
for_each_cpu(cpu, cpus) {
27871f7a8a341e Quentin Perret  2018-12-03  426                          /*
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  427                           * All 
CPUs of a domain must have the same
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  428                           * 
micro-architecture since they all share the same
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  429                           * 
table.
27871f7a8a341e Quentin Perret  2018-12-03  430                           */
8ec59c0f5f4966 Vincent Guittot 2019-06-17  431                          cap = 
arch_scale_cpu_capacity(cpu);
27871f7a8a341e Quentin Perret  2018-12-03  432                          if 
(prev_cap && prev_cap != cap) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  433                                  
dev_err(dev, "EM: CPUs of %*pbl must have the same capacity\n",
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  434                                  
        cpumask_pr_args(cpus));
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  435  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  436                                  
mutex_unlock(&em_pd_mutex);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  437                                  
return -EINVAL;
27871f7a8a341e Quentin Perret  2018-12-03  438                          }
27871f7a8a341e Quentin Perret  2018-12-03  439                          
prev_cap = cap;
27871f7a8a341e Quentin Perret  2018-12-03  440                  }
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  441          }
27871f7a8a341e Quentin Perret  2018-12-03  442  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  443          pd = em_create_pd(dev, 
nr_states, cb, cpus);
27871f7a8a341e Quentin Perret  2018-12-03  444          if (!pd) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  445                  
mutex_unlock(&em_pd_mutex);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  446                  return -EINVAL;
27871f7a8a341e Quentin Perret  2018-12-03  447          }
27871f7a8a341e Quentin Perret  2018-12-03  448  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  449          em_dev = 
kzalloc(sizeof(struct em_device), GFP_KERNEL);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  450          if (!em_dev) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  451                  ret = -ENOMEM;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  452                  goto free_pd;
27871f7a8a341e Quentin Perret  2018-12-03  453          }
27871f7a8a341e Quentin Perret  2018-12-03  454  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  455          em_dev->id = 
ida_simple_get(&em_dev_ida, 0, 0, GFP_KERNEL);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  456          if (em_dev->id < 0) {
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  457                  ret = 
em_dev->id;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  458                  goto 
free_em_dev;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  459          }
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  460  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  461          em_dev->em_pd = pd;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  462          em_dev->dev = dev;
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  463  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  464          
kref_init(&em_dev->kref);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  465          
list_add(&em_dev->em_dev_list, &em_pd_dev_list);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  466  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  467          
em_debug_create_pd(em_dev);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  468          dev_dbg(dev, "EM: 
created perf domain pd%d\n", em_dev->id);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  469  
27871f7a8a341e Quentin Perret  2018-12-03  470          
mutex_unlock(&em_pd_mutex);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  471          return 0;
27871f7a8a341e Quentin Perret  2018-12-03  472  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  473  free_em_dev:
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  474          kfree(em_dev);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  475  free_pd:
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  476          kfree(pd->table);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  477          kfree(pd);
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  478  
9cf8494b5f4eb8 Lukasz Luba     2020-04-10  479          
mutex_unlock(&em_pd_mutex);
27871f7a8a341e Quentin Perret  2018-12-03  480          return ret;
27871f7a8a341e Quentin Perret  2018-12-03  481  }
b4dc5cca354b8a Lukasz Luba     2020-04-10  482  
EXPORT_SYMBOL_GPL(em_dev_register_perf_domain);
b4dc5cca354b8a Lukasz Luba     2020-04-10  483  

:::::: The code at line 394 was first introduced by commit
:::::: 27871f7a8a341ef5c636a337856369acf8013e4e PM: Introduce an Energy Model 
management framework

:::::: TO: Quentin Perret <quentin.per...@arm.com>
:::::: CC: Ingo Molnar <mi...@kernel.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org
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