Re: [Freedreno] [PATCH v3 4/9] PM / QoS: Decouple request alloc from dev_pm_qos_mtx
Hi Rob,
kernel test robot noticed the following build warnings:
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:
https://github.com/intel-lab-lkp/linux/commits/Rob-Clark/PM-devfreq-Drop-unneed-locking-to-appease-lockdep/20230804-060505
base: git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:
https://lore.kernel.org/r/20230803220202.78036-5-robdclark%40gmail.com
patch subject: [PATCH v3 4/9] PM / QoS: Decouple request alloc from
dev_pm_qos_mtx
config: i386-randconfig-m021-20230730
(https://download.01.org/0day-ci/archive/20230804/202308041725.npwswh0l-...@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce:
(https://download.01.org/0day-ci/archive/20230804/202308041725.npwswh0l-...@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
| Reported-by: Dan Carpenter
| Closes: https://lore.kernel.org/r/202308041725.npwswh0l-...@intel.com/
smatch warnings:
drivers/base/power/qos.c:973 dev_pm_qos_update_user_latency_tolerance() warn:
possible memory leak of 'req'
vim +/req +973 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 {
b5ac35ff4296f7 Rob Clark 2023-08-03 925struct
dev_pm_qos_request *req = NULL;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 926int ret;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 927
211fb32e3a0547 Rob Clark 2023-08-03 928ret =
dev_pm_qos_constraints_ensure_allocated(dev);
211fb32e3a0547 Rob Clark 2023-08-03 929if (ret)
211fb32e3a0547 Rob Clark 2023-08-03 930return ret;
211fb32e3a0547 Rob Clark 2023-08-03 931
b5ac35ff4296f7 Rob Clark 2023-08-03 932if
(!dev->power.qos->latency_tolerance_req)
b5ac35ff4296f7 Rob Clark 2023-08-03 933req =
kzalloc(sizeof(*req), GFP_KERNEL);
b5ac35ff4296f7 Rob Clark 2023-08-03 934
2d984ad132a87c Rafael J. Wysocki 2014-02-11 935
mutex_lock(&dev_pm_qos_mtx);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 936
211fb32e3a0547 Rob Clark 2023-08-03 937if
(!dev->power.qos->latency_tolerance_req) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 938if (val < 0) {
80a6f7c79b7822 Andrew Lutomirski 2016-11-29 939if (val
== PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT)
80a6f7c79b7822 Andrew Lutomirski 2016-11-29 940
ret = 0;
80a6f7c79b7822 Andrew Lutomirski 2016-11-29 941else
2d984ad132a87c Rafael J. Wysocki 2014-02-11 942
ret = -EINVAL;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 943goto
out;
kfree(req);?
2d984ad132a87c Rafael J. Wysocki 2014-02-11 944}
2d984ad132a87c Rafael J. Wysocki 2014-02-11 945if (!req) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 946ret =
-ENOMEM;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 947goto
out;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 948}
2d984ad132a87c Rafael J. Wysocki 2014-02-11 949ret =
__dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY_TOLERANCE, val);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 950if (ret < 0) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 951
kfree(req);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 952goto
out;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 953}
2d984ad132a87c Rafael J. Wysocki 2014-02-11 954
dev->power.qos->latency_tolerance_req = req;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 955} else {
b5ac35ff4296f7 Rob Clark 2023-08-03 956/*
b5ac35ff4296f7 Rob Clark 2023-08-03 957 * If we raced
with another thread to allocate the request,
b5ac35ff4296f7 Rob Clark 2023-08-03 958 * simply free
the redundant allocation and move on.
b5ac35ff4296f7 Rob Clark 2023-08-03 959 */
b5ac35ff4296f7 Rob Clark 2023-08-03 960if (req)
b5ac35ff4296f7 Rob Clark 2023-08-03 961
kfree(req);
b5ac35ff4296f7 Rob Clark 2023-08-03 962
2d984ad132a87c Rafael J. Wysocki 2014-02-11 963if (val < 0) {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 964
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY_TOLERANCE);
2d984ad132a87c Rafael J. Wysocki 2014-02-11 965ret = 0;
2d984ad132a87c Rafael J. Wysocki 2014-02-11 966} else {
2d984ad132a87c Rafael J. Wysocki 2014-02-11 967
[Freedreno] [PATCH v3 4/9] PM / QoS: Decouple request alloc from dev_pm_qos_mtx
From: Rob Clark
Similar to the previous patch, move the allocation out from under
dev_pm_qos_mtx, by speculatively doing the allocation and handle
any race after acquiring dev_pm_qos_mtx by freeing the redundant
allocation.
Signed-off-by: Rob Clark
---
drivers/base/power/qos.c | 14 +++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index f3e0c6b65635..4537d93ddb45 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -922,17 +922,19 @@ s32 dev_pm_qos_get_user_latency_tolerance(struct device
*dev)
*/
int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val)
{
+ struct dev_pm_qos_request *req = NULL;
int ret;
ret = dev_pm_qos_constraints_ensure_allocated(dev);
if (ret)
return ret;
+ if (!dev->power.qos->latency_tolerance_req)
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+
mutex_lock(&dev_pm_qos_mtx);
if (!dev->power.qos->latency_tolerance_req) {
- struct dev_pm_qos_request *req;
-
if (val < 0) {
if (val == PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT)
ret = 0;
@@ -940,7 +942,6 @@ int dev_pm_qos_update_user_latency_tolerance(struct device
*dev, s32 val)
ret = -EINVAL;
goto out;
}
- req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req) {
ret = -ENOMEM;
goto out;
@@ -952,6 +953,13 @@ int dev_pm_qos_update_user_latency_tolerance(struct device
*dev, s32 val)
}
dev->power.qos->latency_tolerance_req = req;
} else {
+ /*
+* If we raced with another thread to allocate the request,
+* simply free the redundant allocation and move on.
+*/
+ if (req)
+ kfree(req);
+
if (val < 0) {
__dev_pm_qos_drop_user_request(dev,
DEV_PM_QOS_LATENCY_TOLERANCE);
ret = 0;
--
2.41.0
