Merge "trace: fix preemption disable tracking during context switch to idle" (3163b825) · Commits · e / devices / android_kernel_fairphone_FP4

kernel/sched/core.c

+19 −6

Original line number	Diff line number	Diff line
		@@ -3322,10 +3322,24 @@ struct preempt_store {
		u64 ts;
		unsigned long caddr[4];
		bool irqs_disabled;
		bool is_idle_task;
		};

		DEFINE_PER_CPU(struct preempt_store, the_ps);

		/*
		* This is only called from __schedule() upon context switch.
		*
		* schedule() calls __schedule() with preemption disabled.
		* if we had entered idle and exiting idle now, reset the preemption
		* tracking otherwise we may think preemption is disabled the whole time
		* when the non idle task re-enables the preemption in schedule().
		*/
		static inline void preempt_latency_reset(void)
		{
		if (is_idle_task(this_rq()->curr))
		this_cpu_ptr(&the_ps)->ts = 0;
		}

		/*
		* If the value passed in is equal to the current preempt count
		* then we just disabled preemption. Start timing the latency.
		@@ -3333,7 +3347,6 @@ DEFINE_PER_CPU(struct preempt_store, the_ps);
		static inline void preempt_latency_start(int val)
		{
		int cpu = raw_smp_processor_id();
		struct rq *rq = cpu_rq(cpu);
		struct preempt_store *ps = &per_cpu(the_ps, cpu);

		if (preempt_count() == val) {
		@@ -3347,7 +3360,6 @@ static inline void preempt_latency_start(int val)
		ps->caddr[2] = CALLER_ADDR2;
		ps->caddr[3] = CALLER_ADDR3;
		ps->irqs_disabled = irqs_disabled();
		ps->is_idle_task = (rq->curr == rq->idle);

		trace_preempt_off(CALLER_ADDR0, ip);
		}
		@@ -3384,14 +3396,13 @@ static inline void preempt_latency_stop(int val)
		if (preempt_count() == val) {
		struct preempt_store *ps = &per_cpu(the_ps,
		raw_smp_processor_id());
		u64 delta = sched_clock() - ps->ts;
		u64 delta = ps->ts ? (sched_clock() - ps->ts) : 0;

		/*
		* Trace preempt disable stack if preemption
		* is disabled for more than the threshold.
		*/
		if (!ps->is_idle_task &&
		delta > sysctl_preemptoff_tracing_threshold_ns)
		if (delta > sysctl_preemptoff_tracing_threshold_ns)
		trace_sched_preempt_disable(delta, ps->irqs_disabled,
		ps->caddr[0], ps->caddr[1],
		ps->caddr[2], ps->caddr[3]);
		@@ -3424,6 +3435,7 @@ NOKPROBE_SYMBOL(preempt_count_sub);
		#else
		static inline void preempt_latency_start(int val) { }
		static inline void preempt_latency_stop(int val) { }
		static inline void preempt_latency_reset(void) { }
		#endif

		static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
		@@ -3647,6 +3659,7 @@ static void __sched notrace __schedule(bool preempt)
		if (!prev->on_rq)
		prev->last_sleep_ts = wallclock;

		preempt_latency_reset();
		update_task_ravg(prev, rq, PUT_PREV_TASK, wallclock, 0);
		update_task_ravg(next, rq, PICK_NEXT_TASK, wallclock, 0);
		rq->nr_switches++;