Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull smp hotplug updates from Thomas Gleixner:
 "This is the final round of converting the notifier mess to the state
  machine. The removal of the notifiers and the related infrastructure
  will happen around rc1, as there are conversions outstanding in other
  trees.

  The whole exercise removed about 2000 lines of code in total and in
  course of the conversion several dozen bugs got fixed. The new
  mechanism allows to test almost every hotplug step standalone, so
  usage sites can exercise all transitions extensively.

  There is more room for improvement, like integrating all the
  pointlessly different architecture mechanisms of synchronizing,
  setting cpus online etc into the core code"

* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
  tracing/rb: Init the CPU mask on allocation
  soc/fsl/qbman: Convert to hotplug state machine
  soc/fsl/qbman: Convert to hotplug state machine
  zram: Convert to hotplug state machine
  KVM/PPC/Book3S HV: Convert to hotplug state machine
  arm64/cpuinfo: Convert to hotplug state machine
  arm64/cpuinfo: Make hotplug notifier symmetric
  mm/compaction: Convert to hotplug state machine
  iommu/vt-d: Convert to hotplug state machine
  mm/zswap: Convert pool to hotplug state machine
  mm/zswap: Convert dst-mem to hotplug state machine
  mm/zsmalloc: Convert to hotplug state machine
  mm/vmstat: Convert to hotplug state machine
  mm/vmstat: Avoid on each online CPU loops
  mm/vmstat: Drop get_online_cpus() from init_cpu_node_state/vmstat_cpu_dead()
  tracing/rb: Convert to hotplug state machine
  oprofile/nmi timer: Convert to hotplug state machine
  net/iucv: Use explicit clean up labels in iucv_init()
  x86/pci/amd-bus: Convert to hotplug state machine
  x86/oprofile/nmi: Convert to hotplug state machine
  ...

2 files changed, 42 insertions, 39 deletions

diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c
index 37dc0fe1093f..46730017b3c5 100644
--- a/arch/arm/common/bL_switcher.c
+++ b/arch/arm/common/bL_switcher.c
@@ -757,19 +757,18 @@ EXPORT_SYMBOL_GPL(bL_switcher_put_enabled);
  * while the switcher is active.
  * We're just not ready to deal with that given the trickery involved.
  */
-static int bL_switcher_hotplug_callback(struct notifier_block *nfb,
-					unsigned long action, void *hcpu)
+static int bL_switcher_cpu_pre(unsigned int cpu)
 {
-	if (bL_switcher_active) {
-		int pairing = bL_switcher_cpu_pairing[(unsigned long)hcpu];
-		switch (action & 0xf) {
-		case CPU_UP_PREPARE:
-		case CPU_DOWN_PREPARE:
-			if (pairing == -1)
-				return NOTIFY_BAD;
-		}
-	}
-	return NOTIFY_DONE;
+	int pairing;
+
+	if (!bL_switcher_active)
+		return 0;
+
+	pairing = bL_switcher_cpu_pairing[cpu];
+
+	if (pairing == -1)
+		return -EINVAL;
+	return 0;
 }
 
 static bool no_bL_switcher;
@@ -782,8 +781,15 @@ static int __init bL_switcher_init(void)
 	if (!mcpm_is_available())
 		return -ENODEV;
 
-	cpu_notifier(bL_switcher_hotplug_callback, 0);
-
+	cpuhp_setup_state_nocalls(CPUHP_ARM_BL_PREPARE, "arm/bl:prepare",
+				  bL_switcher_cpu_pre, NULL);
+	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "arm/bl:predown",
+					NULL, bL_switcher_cpu_pre);
+	if (ret < 0) {
+		cpuhp_remove_state_nocalls(CPUHP_ARM_BL_PREPARE);
+		pr_err("bL_switcher: Failed to allocate a hotplug state\n");
+		return ret;
+	}
 	if (!no_bL_switcher) {
 		ret = bL_switcher_enable();
 		if (ret)
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index b8df45883cf7..188180b5523d 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -925,9 +925,9 @@ static bool core_has_os_save_restore(void)
 	}
 }
 
-static void reset_ctrl_regs(void *unused)
+static void reset_ctrl_regs(unsigned int cpu)
 {
-	int i, raw_num_brps, err = 0, cpu = smp_processor_id();
+	int i, raw_num_brps, err = 0;
 	u32 val;
 
 	/*
@@ -1020,25 +1020,20 @@ out_mdbgen:
 		cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
 }
 
-static int dbg_reset_notify(struct notifier_block *self,
-				      unsigned long action, void *cpu)
+static int dbg_reset_online(unsigned int cpu)
 {
-	if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
-		smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
-
-	return NOTIFY_OK;
+	local_irq_disable();
+	reset_ctrl_regs(cpu);
+	local_irq_enable();
+	return 0;
 }
 
-static struct notifier_block dbg_reset_nb = {
-	.notifier_call = dbg_reset_notify,
-};
-
 #ifdef CONFIG_CPU_PM
 static int dbg_cpu_pm_notify(struct notifier_block *self, unsigned long action,
 			     void *v)
 {
 	if (action == CPU_PM_EXIT)
-		reset_ctrl_regs(NULL);
+		reset_ctrl_regs(smp_processor_id());
 
 	return NOTIFY_OK;
 }
@@ -1059,6 +1054,8 @@ static inline void pm_init(void)
 
 static int __init arch_hw_breakpoint_init(void)
 {
+	int ret;
+
 	debug_arch = get_debug_arch();
 
 	if (!debug_arch_supported()) {
@@ -1072,25 +1069,28 @@ static int __init arch_hw_breakpoint_init(void)
 	core_num_brps = get_num_brps();
 	core_num_wrps = get_num_wrps();
 
-	cpu_notifier_register_begin();
-
 	/*
 	 * We need to tread carefully here because DBGSWENABLE may be
 	 * driven low on this core and there isn't an architected way to
 	 * determine that.
 	 */
+	get_online_cpus();
 	register_undef_hook(&debug_reg_hook);
 
 	/*
-	 * Reset the breakpoint resources. We assume that a halting
-	 * debugger will leave the world in a nice state for us.
+	 * Register CPU notifier which resets the breakpoint resources. We
+	 * assume that a halting debugger will leave the world in a nice state
+	 * for us.
 	 */
-	on_each_cpu(reset_ctrl_regs, NULL, 1);
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm/hw_breakpoint:online",
+				dbg_reset_online, NULL);
 	unregister_undef_hook(&debug_reg_hook);
-	if (!cpumask_empty(&debug_err_mask)) {
+	if (WARN_ON(ret < 0) || !cpumask_empty(&debug_err_mask)) {
 		core_num_brps = 0;
 		core_num_wrps = 0;
-		cpu_notifier_register_done();
+		if (ret > 0)
+			cpuhp_remove_state_nocalls(ret);
+		put_online_cpus();
 		return 0;
 	}
 
@@ -1108,12 +1108,9 @@ static int __init arch_hw_breakpoint_init(void)
 			TRAP_HWBKPT, "watchpoint debug exception");
 	hook_ifault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
 			TRAP_HWBKPT, "breakpoint debug exception");
+	put_online_cpus();
 
-	/* Register hotplug and PM notifiers. */
-	__register_cpu_notifier(&dbg_reset_nb);
-
-	cpu_notifier_register_done();
-
+	/* Register PM notifiers. */
 	pm_init();
 	return 0;
 }