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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-02-24 13:25:14 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-02-27 15:07:38 +0100
commit6dbf5cea05a7098a69f294c96b6d76f08562cae5 (patch)
treeb82971769598b518c88773bbb88874875a91aa62 /drivers/cpuidle
parent37efa4b41ffb31dcdfc3beb97d47992bb2a083e5 (diff)
downloadlinux-6dbf5cea05a7098a69f294c96b6d76f08562cae5.tar.bz2
cpuidle: menu: Avoid taking spinlock for accessing QoS values
After commit 9908859acaa9 (cpuidle/menu: add per CPU PM QoS resume latency consideration) the cpuidle menu governor calls dev_pm_qos_read_value() on CPU devices to read the current resume latency QoS constraint values for them. That function takes a spinlock to prevent the device's power.qos pointer from becoming NULL during the access which is a problem for the RT patchset where spinlocks are converted into mutexes and the idle loop stops working. However, it is not even necessary for the menu governor to take that spinlock, because the power.qos pointer accessed under it cannot be modified during the access anyway. For this reason, introduce a "raw" routine for accessing device QoS resume latency constraints without locking and use it in the menu governor. Fixes: 9908859acaa9 (cpuidle/menu: add per CPU PM QoS resume latency consideration) Acked-by: Alex Shi <alex.shi@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/governors/menu.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 8d6d25c38c02..6d6f46e79d94 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -287,7 +287,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
unsigned int interactivity_req;
unsigned int expected_interval;
unsigned long nr_iowaiters, cpu_load;
- int resume_latency = dev_pm_qos_read_value(device);
+ int resume_latency = dev_pm_qos_raw_read_value(device);
if (data->needs_update) {
menu_update(drv, dev);