Merge "perf: Add support for creating events for offline CPU" (44db5480) · Commits · e / devices / android_kernel_fairphone_FP3

include/linux/perf_event.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -497,6 +497,7 @@ struct perf_addr_filters_head {
		* enum perf_event_active_state - the states of a event
		*/
		enum perf_event_active_state {
		PERF_EVENT_STATE_DORMANT = -6,
		PERF_EVENT_STATE_DEAD = -5,
		PERF_EVENT_STATE_ZOMBIE = -4,
		PERF_EVENT_STATE_EXIT = -3,
		@@ -722,6 +723,13 @@ struct perf_event {
		/* Is this event shared with other events */
		bool shared;
		struct list_head zombie_entry;

		/*
		* Entry into the list that holds the events whose CPUs
		* are offline. These events will be installed once the
		* CPU wakes up and will be removed from the list after that
		*/
		struct list_head dormant_event_entry;
		#endif /* CONFIG_PERF_EVENTS */
		};

kernel/events/core.c

+68 −1

Original line number	Diff line number	Diff line
		@@ -2315,6 +2315,19 @@ static void ctx_resched(struct perf_cpu_context *cpuctx,
		perf_pmu_enable(cpuctx->ctx.pmu);
		}

		#if defined CONFIG_HOTPLUG_CPU \|\| defined CONFIG_KEXEC_CORE
		static LIST_HEAD(dormant_event_list);
		static DEFINE_SPINLOCK(dormant_event_list_lock);

		static void perf_prepare_install_in_context(struct perf_event *event)
		{
		spin_lock(&dormant_event_list_lock);
		event->state = PERF_EVENT_STATE_DORMANT;
		list_add_tail(&event->dormant_event_entry, &dormant_event_list);
		spin_unlock(&dormant_event_list_lock);
		}
		#endif

		/*
		* Cross CPU call to install and enable a performance event
		*
		@@ -2391,6 +2404,13 @@ perf_install_in_context(struct perf_event_context *ctx,
		*/
		smp_store_release(&event->ctx, ctx);

		#if defined CONFIG_HOTPLUG_CPU \|\| defined CONFIG_KEXEC_CORE
		if (!cpu_online(cpu)) {
		perf_prepare_install_in_context(event);
		return;
		}
		#endif

		if (!task) {
		cpu_function_call(cpu, __perf_install_in_context, event);
		return;
		@@ -2460,6 +2480,35 @@ perf_install_in_context(struct perf_event_context *ctx,
		raw_spin_unlock_irq(&ctx->lock);
		}

		#if defined CONFIG_HOTPLUG_CPU \|\| defined CONFIG_KEXEC_CORE
		static void perf_deferred_install_in_context(int cpu)
		{
		struct perf_event event, tmp;
		struct perf_event_context *ctx;

		spin_lock(&dormant_event_list_lock);
		list_for_each_entry_safe(event, tmp, &dormant_event_list,
		dormant_event_entry) {
		if (cpu != event->cpu)
		continue;

		list_del(&event->dormant_event_entry);
		event->state = PERF_EVENT_STATE_INACTIVE;
		spin_unlock(&dormant_event_list_lock);

		ctx = event->ctx;
		perf_event__state_init(event);

		mutex_lock(&ctx->mutex);
		perf_install_in_context(ctx, event, cpu);
		mutex_unlock(&ctx->mutex);

		spin_lock(&dormant_event_list_lock);
		}
		spin_unlock(&dormant_event_list_lock);
		}
		#endif

		/*
		* Put a event into inactive state and update time fields.
		* Enabling the leader of a group effectively enables all
		@@ -4300,10 +4349,12 @@ static int __perf_event_release_kernel(struct perf_event *event)
		* back online.
		*/
		#if defined CONFIG_HOTPLUG_CPU \|\| defined CONFIG_KEXEC_CORE
		if (event->cpu != -1 && per_cpu(is_hotplugging, event->cpu)) {
		if (event->cpu != -1 && per_cpu(is_hotplugging, event->cpu))
		if (event->state == PERF_EVENT_STATE_ZOMBIE)
		return 0;

		if (!cpu_online(event->cpu) &&
		event->state == PERF_EVENT_STATE_ACTIVE) {
		event->state = PERF_EVENT_STATE_ZOMBIE;

		spin_lock(&zombie_list_lock);
		@@ -4312,6 +4363,11 @@ static int __perf_event_release_kernel(struct perf_event *event)

		return 0;
		}

		spin_lock(&dormant_event_list_lock);
		if (event->state == PERF_EVENT_STATE_DORMANT)
		list_del(&event->dormant_event_entry);
		spin_unlock(&dormant_event_list_lock);
		#endif

		/*
		@@ -4632,6 +4688,15 @@ perf_read(struct file file, char __user buf, size_t count, loff_t *ppos)
		struct perf_event_context *ctx;
		int ret;

		#if defined CONFIG_HOTPLUG_CPU \|\| defined CONFIG_KEXEC_CORE
		spin_lock(&dormant_event_list_lock);
		if (event->state == PERF_EVENT_STATE_DORMANT) {
		spin_unlock(&dormant_event_list_lock);
		return 0;
		}
		spin_unlock(&dormant_event_list_lock);
		#endif

		ctx = perf_event_ctx_lock(event);
		ret = __perf_read(event, buf, count);
		perf_event_ctx_unlock(event, ctx);
		@@ -9466,6 +9531,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
		mutex_init(&event->child_mutex);
		INIT_LIST_HEAD(&event->child_list);

		INIT_LIST_HEAD(&event->dormant_event_entry);
		INIT_LIST_HEAD(&event->group_entry);
		INIT_LIST_HEAD(&event->event_entry);
		INIT_LIST_HEAD(&event->sibling_list);
		@@ -11169,6 +11235,7 @@ static int perf_event_start_swevents(unsigned int cpu)

		mutex_lock(&pmus_lock);
		perf_event_zombie_cleanup(cpu);
		perf_deferred_install_in_context(cpu);

		idx = srcu_read_lock(&pmus_srcu);
		list_for_each_entry_rcu(pmu, &pmus, entry) {