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

[Dan Carpenter]

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 at intel.com>
| Reported-by: Dan Carpenter <error27 at 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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