Merge "sched: Ensure watchdog is enabled before disabling" (527706a7) · Commits · e / devices / android_kernel_oneplus_sm8150

kernel/sched/core.c

+17 −0

Original line number	Original line	Diff line number	Diff line
	@@ -27,6 +27,7 @@
	#include <linux/security.h>		#include <linux/security.h>
	#include <linux/syscalls.h>		#include <linux/syscalls.h>
	#include <linux/irq.h>		#include <linux/irq.h>
			#include <linux/delay.h>

	#include <linux/kthread.h>		#include <linux/kthread.h>

	@@ -5985,6 +5986,22 @@ int sched_isolate_cpu(int cpu)
	if (++cpu_isolation_vote[cpu] > 1)		if (++cpu_isolation_vote[cpu] > 1)
	goto out;		goto out;

			/*
			* There is a race between watchdog being enabled by hotplug and
			* core isolation disabling the watchdog. When a CPU is hotplugged in
			* and the hotplug lock has been released the watchdog thread might
			* not have run yet to enable the watchdog.
			* We have to wait for the watchdog to be enabled before proceeding.
			*/
			if (!watchdog_configured(cpu)) {
			msleep(20);
			if (!watchdog_configured(cpu)) {
			--cpu_isolation_vote[cpu];
			ret_code = -EBUSY;
			goto out;
			}
			}

	set_cpu_isolated(cpu, true);		set_cpu_isolated(cpu, true);
	cpumask_clear_cpu(cpu, &avail_cpus);		cpumask_clear_cpu(cpu, &avail_cpus);

kernel/watchdog.c

+20 −8

Original line number	Original line	Diff line number	Diff line
	@@ -456,17 +456,13 @@ static void watchdog_set_prio(unsigned int policy, unsigned int prio)
	sched_setscheduler(current, policy, &param);		sched_setscheduler(current, policy, &param);
	}		}

	/* Must be called with hotplug lock (lock_device_hotplug()) held. */
	void watchdog_enable(unsigned int cpu)		void watchdog_enable(unsigned int cpu)
	{		{
	struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);		struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
	unsigned int *enabled = this_cpu_ptr(&watchdog_en);		unsigned int *enabled = this_cpu_ptr(&watchdog_en);

	lock_device_hotplug_assert();

	if (*enabled)		if (*enabled)
	return;		return;
	*enabled = 1;

	/*		/*
	* Start the timer first to prevent the NMI watchdog triggering		* Start the timer first to prevent the NMI watchdog triggering
	@@ -484,19 +480,24 @@ void watchdog_enable(unsigned int cpu)
	watchdog_nmi_enable(cpu);		watchdog_nmi_enable(cpu);

	watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);		watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);

			/*
			* Need to ensure above operations are observed by other CPUs before
			* indicating that timer is enabled. This is to synchronize core
			* isolation and hotplug. Core isolation will wait for this flag to be
			* set.
			*/
			mb();
			*enabled = 1;
	}		}

	/* Must be called with hotplug lock (lock_device_hotplug()) held. */
	void watchdog_disable(unsigned int cpu)		void watchdog_disable(unsigned int cpu)
	{		{
	struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);		struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
	unsigned int *enabled = this_cpu_ptr(&watchdog_en);		unsigned int *enabled = this_cpu_ptr(&watchdog_en);

	lock_device_hotplug_assert();

	if (!*enabled)		if (!*enabled)
	return;		return;
	*enabled = 0;

	watchdog_set_prio(SCHED_NORMAL, 0);		watchdog_set_prio(SCHED_NORMAL, 0);
	/*		/*
	@@ -506,6 +507,17 @@ void watchdog_disable(unsigned int cpu)
	*/		*/
	watchdog_nmi_disable(cpu);		watchdog_nmi_disable(cpu);
	hrtimer_cancel(hrtimer);		hrtimer_cancel(hrtimer);

			/*
			* No need for barrier here since disabling the watchdog is
			* synchronized with hotplug lock
			*/
			*enabled = 0;
			}

			bool watchdog_configured(unsigned int cpu)
			{
			return *per_cpu_ptr(&watchdog_en, cpu);
	}		}

	static void watchdog_cleanup(unsigned int cpu, bool online)		static void watchdog_cleanup(unsigned int cpu, bool online)