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

Dan Carpenter
2023-03-21T04:53:43Z

Hi Rob,

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: arm64-randconfig-m041-20230319 (https://download.01.org/0day-ci/archive/20230321/202303211207.mUCSt3CK-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Link: https://lore.kernel.org/r/202303211207.mUCSt3CK-lkp@intel.com/

smatch warnings:
drivers/base/power/qos.c:947 dev_pm_qos_update_user_latency_tolerance() error: uninitialized symbol 'req'.
drivers/base/power/qos.c:975 dev_pm_qos_update_user_latency_tolerance() warn: possible memory leak of 'req'

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

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;

This "req" shadows the ealier 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) {

So it leads to an unintialized variable and a leak.

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 }

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