Re: [PATCH v2 18/23] PM / QoS: Decouple request alloc from dev_pm_qos_mtx

kernel test robot
2023-03-20T20:14:22Z

Hi Rob,

I love your patch! Perhaps something to improve:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on rafael-pm/linux-next drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-tip/drm-tip linus/master v6.3-rc3 next-20230320]
[cannot apply to chanwoo/devfreq-testing]
[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/Rob-Clark/drm-msm-Pre-allocate-hw_fence/20230320-224826
base: git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link: https://lore.kernel.org/r/20230320144356.803762-19-robdclark%40gmail.com
patch subject: [PATCH v2 18/23] PM / QoS: Decouple request alloc from dev_pm_qos_mtx
config: arm-randconfig-r005-20230319 (https://download.01.org/0day-ci/archive/20230321/202303210444.Qtybv08z-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 67409911353323ca5edf2049ef0df54132fa1ca7)
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
# install arm cross compiling tool for clang build
# apt-get install binutils-arm-linux-gnueabi
# https://github.com/intel-lab-lkp/linux/commit/2d7e4629d7265d7e77fc72d01e84d27d805b7485
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Rob-Clark/drm-msm-Pre-allocate-hw_fence/20230320-224826
git checkout 2d7e4629d7265d7e77fc72d01e84d27d805b7485
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/base/power/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303210444.Qtybv08z-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/base/power/qos.c:947:8: warning: variable 'req' is uninitialized when used here [-Wuninitialized]
if (!req) {
^~~
drivers/base/power/qos.c:938:33: note: initialize the variable 'req' to silence this warning
struct dev_pm_qos_request *req;
^
= NULL
1 warning generated.

vim +/req +947 drivers/base/power/qos.c

2d984ad132a87c Rafael J. Wysocki 2014-02-11 917
2d984ad132a87c Rafael J. Wysocki 2014-02-11 918 /**
2d984ad132a87c Rafael J. Wysocki 2014-02-11 919 * dev_pm_qos_update_user_latency_tolerance - Update user space latency tolerance.
2d984ad132a87c Rafael J. Wysocki 2014-02-11 920 * @dev: Device to update the user space latency tolerance for.
2d984ad132a87c Rafael J. Wysocki 2014-02-11 921 * @val: New user space latency tolerance for @dev (negative values disable).
2d984ad132a87c Rafael J. Wysocki 2014-02-11 922 */
2d984ad132a87c Rafael J. Wysocki 2014-02-11 923 int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val)
2d984ad132a87c Rafael J. Wysocki 2014-02-11 924 {
2d7e4629d7265d Rob Clark 2023-03-20 925 struct dev_pm_qos_request *req = NULL;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 926 int ret;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 927
00dd582e52a535 Rob Clark 2023-03-20 928 ret = dev_pm_qos_constraints_ensure_allocated(dev);
00dd582e52a535 Rob Clark 2023-03-20 929 if (ret)
00dd582e52a535 Rob Clark 2023-03-20 930 return ret;
00dd582e52a535 Rob Clark 2023-03-20 931
2d7e4629d7265d Rob Clark 2023-03-20 932 if (!dev->power.qos->latency_tolerance_req)
2d7e4629d7265d Rob Clark 2023-03-20 933 req = kzalloc(sizeof(*req), GFP_KERNEL);
2d7e4629d7265d Rob Clark 2023-03-20 934
2d984ad132a87c Rafael J. Wysocki 2014-02-11 935 mutex_lock(&dev_pm_qos_mtx);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 936
00dd582e52a535 Rob Clark 2023-03-20 937 if (!dev->power.qos->latency_tolerance_req) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 938 struct dev_pm_qos_request *req;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 939
2d984ad132a87c Rafael J. Wysocki 2014-02-11 940 if (val < 0) {
80a6f7c79b7822 Andrew Lutomirski 2016-11-29 941 if (val == PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT)
80a6f7c79b7822 Andrew Lutomirski 2016-11-29 942 ret = 0;
80a6f7c79b7822 Andrew Lutomirski 2016-11-29 943 else
2d984ad132a87c Rafael J. Wysocki 2014-02-11 944 ret = -EINVAL;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 945 goto out;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 946 }
2d984ad132a87c Rafael J. Wysocki 2014-02-11 @947 if (!req) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 948 ret = -ENOMEM;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 949 goto out;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 950 }
2d984ad132a87c Rafael J. Wysocki 2014-02-11 951 ret = __dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY_TOLERANCE, val);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 952 if (ret < 0) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 953 kfree(req);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 954 goto out;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 955 }
2d984ad132a87c Rafael J. Wysocki 2014-02-11 956 dev->power.qos->latency_tolerance_req = req;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 957 } else {
2d7e4629d7265d Rob Clark 2023-03-20 958 /*
2d7e4629d7265d Rob Clark 2023-03-20 959 * If we raced with another thread to allocate the request,
2d7e4629d7265d Rob Clark 2023-03-20 960 * simply free the redundant allocation and move on.
2d7e4629d7265d Rob Clark 2023-03-20 961 */
2d7e4629d7265d Rob Clark 2023-03-20 962 if (req)
2d7e4629d7265d Rob Clark 2023-03-20 963 kfree(req);
2d7e4629d7265d Rob Clark 2023-03-20 964
2d984ad132a87c Rafael J. Wysocki 2014-02-11 965 if (val < 0) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 966 __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY_TOLERANCE);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 967 ret = 0;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 968 } else {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 969 ret = __dev_pm_qos_update_request(dev->power.qos->latency_tolerance_req, val);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 970 }
2d984ad132a87c Rafael J. Wysocki 2014-02-11 971 }
2d984ad132a87c Rafael J. Wysocki 2014-02-11 972
2d984ad132a87c Rafael J. Wysocki 2014-02-11 973 out:
2d984ad132a87c Rafael J. Wysocki 2014-02-11 974 mutex_unlock(&dev_pm_qos_mtx);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 975 return ret;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 976 }
034e7906211c18 Andrew Lutomirski 2016-11-29 977 EXPORT_SYMBOL_GPL(dev_pm_qos_update_user_latency_tolerance);
13b2c4a0c3b1cd Mika Westerberg 2015-07-27 978

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