Re: [PATCH] PM: QoS: Introduce boot parameter pm_qos_resume_latency_us

[kernel test robot <lkp@intel.com>]

Hi Aaron,

kernel test robot noticed the following build warnings:

[auto build test WARNING on driver-core/driver-core-testing]
[also build test WARNING on driver-core/driver-core-next driver-core/driver-core-linus rafael-pm/linux-next rafael-pm/bleeding-edge linus/master amd-pstate/linux-next amd-pstate/bleeding-edge v6.19-rc6 next-20260122]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Aaron-Tomlin/PM-QoS-Introduce-boot-parameter-pm_qos_resume_latency_us/20260123-090409
base:   driver-core/driver-core-testing
patch link:    https://lore.kernel.org/r/20260123010024.3301276-1-atomlin%40atomlin.com
patch subject: [PATCH] PM: QoS: Introduce boot parameter pm_qos_resume_latency_us
config: x86_64-randconfig-161-20260123 (https://download.01.org/0day-ci/archive/20260123/202601231616.nbo2ijJf-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
smatch version: v0.5.0-8994-gd50c5a4c
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260123/202601231616.nbo2ijJf-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601231616.nbo2ijJf-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/power/qos.c:339:9: warning: variable 'ret' is uninitialized when used here [-Wuninitialized]
     339 |         return ret;
         |                ^~~
   kernel/power/qos.c:266:9: note: initialize the variable 'ret' to silence this warning
     266 |         int ret;
         |                ^
         |                 = 0
   kernel/power/qos.c:354:5: error: redefinition of 'pm_qos_get_boot_cpu_latency_limit'
     354 | s32 pm_qos_get_boot_cpu_latency_limit(unsigned int cpu)
         |     ^
   include/linux/pm_qos.h:222:19: note: previous definition is here
     222 | static inline s32 pm_qos_get_boot_cpu_latency_limit(unsigned int cpu)
         |                   ^
   1 warning and 1 error generated.


vim +/ret +339 kernel/power/qos.c

   245	
   246	/* init_pm_qos_latency_us_setup - Parse the pm_qos_latency_us boot parameter.
   247	 *
   248	 * Parses the kernel command line option "pm_qos_resume_latency_us=" to establish
   249	 * per-CPU resume latency constraints. These constraints are applied
   250	 * immediately when a CPU is registered.
   251	 *
   252	 * Syntax: pm_qos_resume_latency_us=<cpu-list>:<value>[,<cpu-list>:<value>...]
   253	 * Example: pm_qos_resume_latency_us=0-3:0,4-7:20
   254	 *
   255	 * The parsing logic enforces a "First Match Wins" policy. If a CPU is
   256	 * covered by multiple entries in the list, only the first valid entry
   257	 * applies. Any subsequent overlapping ranges for that CPU are ignored.
   258	 *
   259	 * Return: 0 on success, or a negative error code on failure.
   260	 */
   261	static int __init init_pm_qos_latency_us_setup(void)
   262	{
   263		char *token, *cmd = pm_qos_resume_latency_cmdline;
   264		struct pm_qos_boot_entry *entry, *tentry;
   265		cpumask_var_t covered;
   266		int ret;
   267	
   268		if (boot_option_idle_override == IDLE_POLL) {
   269			pr_warn("pm_qos: Cannot be used with idle=poll\n");
   270			return -EINVAL;
   271		}
   272	
   273		if (!zalloc_cpumask_var(&covered, GFP_KERNEL)) {
   274			pr_warn("pm_qos: Failed to allocate memory for parsing boot parameter\n");
   275			return -ENOMEM;
   276		}
   277	
   278		while ((token = strsep(&cmd, ",")) != NULL) {
   279			char *str_range, *str_val;
   280	
   281			str_range = strsep(&token, ":");
   282			str_val = token;
   283	
   284			if (!str_val) {
   285				pr_warn("pm_qos: Missing value range %s\n",
   286					str_range);
   287				continue;
   288			}
   289	
   290			entry = kzalloc(sizeof(*entry), GFP_KERNEL);
   291			if (!entry) {
   292				pr_warn("pm_qos: Failed to allocate memory for boot entry\n");
   293				goto cleanup;
   294			}
   295	
   296			if (cpulist_parse(str_range, &entry->mask)) {
   297				pr_warn("pm_qos: Failed to parse cpulist range %s\n",
   298					str_range);
   299				kfree(entry);
   300				continue;
   301			}
   302	
   303			cpumask_andnot(&entry->mask, &entry->mask, covered);
   304			if (cpumask_empty(&entry->mask)) {
   305				pr_warn("pm_qos: Entry %s already covered, ignoring\n",
   306					str_range);
   307				kfree(entry);
   308				continue;
   309			}
   310			cpumask_or(covered, covered, &entry->mask);
   311	
   312			if (kstrtos32(str_val, 0, &entry->latency)) {
   313				pr_warn("pm_qos: Invalid latency requirement value %s\n",
   314					str_val);
   315				kfree(entry);
   316				continue;
   317			}
   318	
   319			if (entry->latency < 0) {
   320				pr_warn("pm_qos: Latency requirement cannot be negative: %d\n",
   321					entry->latency);
   322				kfree(entry);
   323				continue;
   324			}
   325	
   326			list_add_tail(&entry->node, &pm_qos_boot_list);
   327		}
   328	
   329		free_cpumask_var(covered);
   330		return 0;
   331	
   332	cleanup:
   333		list_for_each_entry_safe(entry, tentry, &pm_qos_boot_list, node) {
   334			list_del(&entry->node);
   335			kfree(entry);
   336		}
   337	
   338		free_cpumask_var(covered);
 > 339		return ret;
   340	}
   341	early_initcall(init_pm_qos_latency_us_setup);
   342	

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