Revert "perf: Add PM notifiers to fix CPU hotplug races"

This reverts commit 144060fee07e9c22e179d00819c83c86fbcbf82c.

It causes a resume regression for Andi on his Acer Aspire 1830T post
3.1.  The screen just stays black after wakeup.

Also, it really looks like the wrong way to suspend and resume perf
events: I think they should be done as part of the CPU suspend and
resume, rather than as a notifier that does smp_call_function().

Reported-by: Andi Kleen <andi@firstfloor.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/events/core.c

@@ -29,7 +29,6 @@
 #include <linux/hardirq.h>
 #include <linux/rculist.h>
 #include <linux/uaccess.h>
-#include <linux/suspend.h>
 #include <linux/syscalls.h>
 #include <linux/anon_inodes.h>
 #include <linux/kernel_stat.h>
@@ -6853,7 +6852,7 @@ static void __cpuinit perf_event_init_cpu(int cpu)
 	struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
 	mutex_lock(&swhash->hlist_mutex);
-	if (swhash->hlist_refcount > 0 && !swhash->swevent_hlist) {
+	if (swhash->hlist_refcount > 0) {
 		struct swevent_hlist *hlist;
 
 		hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));
@@ -6942,14 +6941,7 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (long)hcpu;
 
-	/*
-	 * Ignore suspend/resume action, the perf_pm_notifier will
-	 * take care of that.
-	 */
-	if (action & CPU_TASKS_FROZEN)
-		return NOTIFY_OK;
-
-	switch (action) {
+	switch (action & ~CPU_TASKS_FROZEN) {
 
 	case CPU_UP_PREPARE:
 	case CPU_DOWN_FAILED:
@@ -6968,90 +6960,6 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
 	return NOTIFY_OK;
 }
 
-static void perf_pm_resume_cpu(void *unused)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event_context *ctx;
-	struct pmu *pmu;
-	int idx;
-
-	idx = srcu_read_lock(&pmus_srcu);
-	list_for_each_entry_rcu(pmu, &pmus, entry) {
-		cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
-		ctx = cpuctx->task_ctx;
-
-		perf_ctx_lock(cpuctx, ctx);
-		perf_pmu_disable(cpuctx->ctx.pmu);
-
-		cpu_ctx_sched_out(cpuctx, EVENT_ALL);
-		if (ctx)
-			ctx_sched_out(ctx, cpuctx, EVENT_ALL);
-
-		perf_pmu_enable(cpuctx->ctx.pmu);
-		perf_ctx_unlock(cpuctx, ctx);
-	}
-	srcu_read_unlock(&pmus_srcu, idx);
-}
-
-static void perf_pm_suspend_cpu(void *unused)
-{
-	struct perf_cpu_context *cpuctx;
-	struct perf_event_context *ctx;
-	struct pmu *pmu;
-	int idx;
-
-	idx = srcu_read_lock(&pmus_srcu);
-	list_for_each_entry_rcu(pmu, &pmus, entry) {
-		cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
-		ctx = cpuctx->task_ctx;
-
-		perf_ctx_lock(cpuctx, ctx);
-		perf_pmu_disable(cpuctx->ctx.pmu);
-
-		perf_event_sched_in(cpuctx, ctx, current);
-
-		perf_pmu_enable(cpuctx->ctx.pmu);
-		perf_ctx_unlock(cpuctx, ctx);
-	}
-	srcu_read_unlock(&pmus_srcu, idx);
-}
-
-static int perf_resume(void)
-{
-	get_online_cpus();
-	smp_call_function(perf_pm_resume_cpu, NULL, 1);
-	put_online_cpus();
-
-	return NOTIFY_OK;
-}
-
-static int perf_suspend(void)
-{
-	get_online_cpus();
-	smp_call_function(perf_pm_suspend_cpu, NULL, 1);
-	put_online_cpus();
-
-	return NOTIFY_OK;
-}
-
-static int perf_pm(struct notifier_block *self, unsigned long action, void *ptr)
-{
-	switch (action) {
-	case PM_POST_HIBERNATION:
-	case PM_POST_SUSPEND:
-		return perf_resume();
-	case PM_HIBERNATION_PREPARE:
-	case PM_SUSPEND_PREPARE:
-		return perf_suspend();
-	default:
-		return NOTIFY_DONE;
-	}
-}
-
-static struct notifier_block perf_pm_notifier = {
-	.notifier_call = perf_pm,
-};
-
 void __init perf_event_init(void)
 {
 	int ret;
@@ -7066,7 +6974,6 @@ void __init perf_event_init(void)
 	perf_tp_register();
 	perf_cpu_notifier(perf_cpu_notify);
 	register_reboot_notifier(&perf_reboot_notifier);
-	register_pm_notifier(&perf_pm_notifier);
 
 	ret = init_hw_breakpoint();
 	WARN(ret, "hw_breakpoint initialization failed with: %d", ret);