[PATCH v2] thermal/intel_powerclamp: Fix sched_setscheduler fail

[xinwu . liu]

From: "Liu, Xinwu" <xinwu.liu@xxxxxxxxx>

The schedule policy of thread "kidle_inject" is SCHED_NORMAL:
[  772.796284] intel_powerclamp: Start idle injection to reduce power
[  772.825757] ------------[ cut here ]------------
[  772.825877] WARNING: CPU: 0 PID: 2140 at ../../../../../../kernel/glv/kernel/sched/idle.c:298 play_idle+0x16f/0x230
[  772.826096] Modules linked in: ip6table_raw iptable_raw hci_uart bluetooth rfkill_gpio cfg80211 imc_ipc(O)
[  772.826194] CPU: 0 PID: 2140 Comm: kidle_inject/0 Tainted: G          IO    4.9.0-ge701680f3a17 #1
[  772.826373]  ffffc90001103d58 ffffffff813ba085 0000000000000000 0000000000000000
[  772.826552]  ffffc90001103d98 ffffffff810953e1 0000012a691441c0 0000000000000006
[  772.826731]  0000000000000002 ffff88006a39d708 ffff8800691441c0 ffffe8ffffc0dab8
[  772.826794] Call Trace:
[  772.826903]  [<ffffffff813ba085>] dump_stack+0x67/0x92
[  772.827007]  [<ffffffff810953e1>] __warn+0xd1/0xf0
[  772.827124]  [<ffffffff810954cd>] warn_slowpath_null+0x1d/0x20
[  772.827234]  [<ffffffff810d6c6f>] play_idle+0x16f/0x230
[  772.827365]  [<ffffffff81a9b4b7>] ? __schedule+0x217/0x6f0
[  772.827485]  [<ffffffff81856c9a>] clamp_idle_injection_func+0x6a/0x1f0
[  772.827612]  [<ffffffff810b568d>] kthread_worker_fn+0xdd/0x200
[  772.827741]  [<ffffffff810b55b0>] ? __kthread_init_worker+0x50/0x50
[  772.827860]  [<ffffffff810b5542>] kthread+0x102/0x120
[  772.828004]  [<ffffffff810b5440>] ? kthread_park+0x60/0x60
[  772.828118]  [<ffffffff81aa2517>] ret_from_fork+0x27/0x40
[  772.828228] ---[ end trace bb738d5d79381554 ]---

Normaly, the user thread have not the capability "CAP_SYS_NICE"
(and they shouldn't), it will fail to change the schedule policy.
So, fix it by changing by themselves.

Signed-off-by: Liu, Xinwu <xinwu.liu@xxxxxxxxx>
Signed-off-by: Zhang, Di <di.zhang@xxxxxxxxx>
---
 drivers/thermal/intel_powerclamp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/intel_powerclamp.c b/drivers/thermal/intel_powerclamp.c
index 83e6971..ea2d9cf 100644
--- a/drivers/thermal/intel_powerclamp.c
+++ b/drivers/thermal/intel_powerclamp.c
@@ -377,6 +377,7 @@ static bool powerclamp_adjust_controls(unsigned int target_ratio,
 	return set_target_ratio + guard <= current_ratio;
 }
 
+static DEFINE_PER_CPU(int, setscheduler_done);
 static void clamp_balancing_func(struct kthread_work *work)
 {
 	struct powerclamp_worker_data *w_data;
@@ -388,6 +389,10 @@ static void clamp_balancing_func(struct kthread_work *work)
 	w_data = container_of(work, struct powerclamp_worker_data,
 			      balancing_work);
 
+	if (unlikely(this_cpu_read(setscheduler_done) == 0)) {
+		sched_setscheduler(current, SCHED_FIFO, &sparam);
+		this_cpu_inc(setscheduler_done);
+	}
 	/*
 	 * make sure user selected ratio does not take effect until
 	 * the next round. adjust target_ratio if user has changed
@@ -507,7 +512,6 @@ static void start_power_clamp_worker(unsigned long cpu)
 	w_data->cpu = cpu;
 	w_data->clamping = true;
 	set_bit(cpu, cpu_clamping_mask);
-	sched_setscheduler(worker->task, SCHED_FIFO, &sparam);
 	kthread_init_work(&w_data->balancing_work, clamp_balancing_func);
 	kthread_init_delayed_work(&w_data->idle_injection_work,
 				  clamp_idle_injection_func);
-- 
1.9.1