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Subject[rui:amd-pstate-dev-v4 7/22] drivers/cpufreq/amd-pstate.c:193:6: warning: variable 'des_perf' is used uninitialized whenever 'if' condition is false
tree:   https://git.kernel.org/pub/scm/linux/kernel/git/rui/linux.git amd-pstate-dev-v4
head: 17a6d8cd0f5821b7a5ebd40fe1491a0c77a9c306
commit: 2adf4a47fba000e94b1976144af27a51d2ddcd4e [7/22] cpufreq: amd: add fast switch function for amd-pstate
config: x86_64-randconfig-r036-20211126 (https://download.01.org/0day-ci/archive/20211127/202111271256.9GZ2i3ea-lkp@intel.com/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 5162b558d8c0b542e752b037e72a69d5fd51eb1e)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/rui/linux.git/commit/?id=2adf4a47fba000e94b1976144af27a51d2ddcd4e
git remote add rui https://git.kernel.org/pub/scm/linux/kernel/git/rui/linux.git
git fetch --no-tags rui amd-pstate-dev-v4
git checkout 2adf4a47fba000e94b1976144af27a51d2ddcd4e
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/cpufreq/ drivers/gpio/

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

All warnings (new ones prefixed by >>):

>> drivers/cpufreq/amd-pstate.c:193:6: warning: variable 'des_perf' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (target_perf < capacity)
^~~~~~~~~~~~~~~~~~~~~~
drivers/cpufreq/amd-pstate.c:207:36: note: uninitialized use occurs here
des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
^~~~~~~~
include/linux/minmax.h:124:60: note: expanded from macro 'clamp_t'
#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
^~~
include/linux/minmax.h:112:48: note: expanded from macro 'max_t'
#define max_t(type, x, y) __careful_cmp((type)(x), (type)(y), >)
^
include/linux/minmax.h:38:14: note: expanded from macro '__careful_cmp'
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
^
note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
include/linux/minmax.h:104:48: note: expanded from macro 'min_t'
#define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <)
^
include/linux/minmax.h:38:14: note: expanded from macro '__careful_cmp'
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
^
include/linux/minmax.h:31:25: note: expanded from macro '__cmp_once'
typeof(x) unique_x = (x); \
^
drivers/cpufreq/amd-pstate.c:193:2: note: remove the 'if' if its condition is always true
if (target_perf < capacity)
^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/cpufreq/amd-pstate.c:185:44: note: initialize the variable 'des_perf' to silence this warning
unsigned long max_perf, min_perf, des_perf,
^
= 0
1 warning generated.


vim +193 drivers/cpufreq/amd-pstate.c

179
180 static void amd_pstate_adjust_perf(unsigned int cpu,
181 unsigned long _min_perf,
182 unsigned long target_perf,
183 unsigned long capacity)
184 {
185 unsigned long max_perf, min_perf, des_perf,
186 cap_perf, lowest_nonlinear_perf;
187 struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
188 struct amd_cpudata *cpudata = policy->driver_data;
189
190 cap_perf = READ_ONCE(cpudata->highest_perf);
191 lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
192
> 193 if (target_perf < capacity)
194 des_perf = DIV_ROUND_UP(cap_perf * target_perf, capacity);
195
196 min_perf = READ_ONCE(cpudata->highest_perf);
197 if (_min_perf < capacity)
198 min_perf = DIV_ROUND_UP(cap_perf * _min_perf, capacity);
199
200 if (min_perf < lowest_nonlinear_perf)
201 min_perf = lowest_nonlinear_perf;
202
203 max_perf = cap_perf;
204 if (max_perf < min_perf)
205 max_perf = min_perf;
206
207 des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
208
209 amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true);
210 }
211

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

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