Merge commit '8700c95adb03' into timers/nohz

The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.

Merge a common upstream merge point that has these
updates.

Conflicts:
	include/linux/perf_event.h
	kernel/rcutree.h
	kernel/rcutree_plugin.h

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

2 files changed, 77 insertions, 46 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 8f97a7407714..66f67afad4fa 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -28,10 +28,6 @@ config BUILDTIME_EXTABLE_SORT
 
 menu "General setup"
 
-config EXPERIMENTAL
-	bool
-	default y
-
 config BROKEN
 	bool
 
@@ -583,13 +579,16 @@ config RCU_FAST_NO_HZ
 	depends on NO_HZ_COMMON && SMP
 	default n
 	help
-	  This option causes RCU to attempt to accelerate grace periods in
-	  order to allow CPUs to enter dynticks-idle state more quickly.
-	  On the other hand, this option increases the overhead of the
-	  dynticks-idle checking, thus degrading scheduling latency.
+	  This option permits CPUs to enter dynticks-idle state even if
+	  they have RCU callbacks queued, and prevents RCU from waking
+	  these CPUs up more than roughly once every four jiffies (by
+	  default, you can adjust this using the rcutree.rcu_idle_gp_delay
+	  parameter), thus improving energy efficiency.  On the other
+	  hand, this option increases the duration of RCU grace periods,
+	  for example, slowing down synchronize_rcu().
 
-	  Say Y if energy efficiency is critically important, and you don't
-	  	care about real-time response.
+	  Say Y if energy efficiency is critically important, and you
+	  	don't care about increased grace-period durations.
 
 	  Say N if you are unsure.
 
@@ -656,7 +655,7 @@ config RCU_BOOST_DELAY
 	  Accept the default if unsure.
 
 config RCU_NOCB_CPU
-	bool "Offload RCU callback processing from boot-selected CPUs"
+	bool "Offload RCU callback processing from boot-selected CPUs (EXPERIMENTAL"
 	depends on TREE_RCU || TREE_PREEMPT_RCU
 	default n
 	help
@@ -667,16 +666,56 @@ config RCU_NOCB_CPU
 
 	  This option offloads callback invocation from the set of
 	  CPUs specified at boot time by the rcu_nocbs parameter.
-	  For each such CPU, a kthread ("rcuoN") will be created to
-	  invoke callbacks, where the "N" is the CPU being offloaded.
-	  Nothing prevents this kthread from running on the specified
-	  CPUs, but (1) the kthreads may be preempted between each
-	  callback, and (2) affinity or cgroups can be used to force
-	  the kthreads to run on whatever set of CPUs is desired.
-
-	  Say Y here if you want reduced OS jitter on selected CPUs.
+	  For each such CPU, a kthread ("rcuox/N") will be created to
+	  invoke callbacks, where the "N" is the CPU being offloaded,
+	  and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
+	  "s" for RCU-sched.  Nothing prevents this kthread from running
+	  on the specified CPUs, but (1) the kthreads may be preempted
+	  between each callback, and (2) affinity or cgroups can be used
+	  to force the kthreads to run on whatever set of CPUs is desired.
+
+	  Say Y here if you want to help to debug reduced OS jitter.
 	  Say N here if you are unsure.
 
+choice
+	prompt "Build-forced no-CBs CPUs"
+	default RCU_NOCB_CPU_NONE
+	help
+	  This option allows no-CBs CPUs to be specified at build time.
+	  Additional no-CBs CPUs may be specified by the rcu_nocbs=
+	  boot parameter.
+
+config RCU_NOCB_CPU_NONE
+	bool "No build_forced no-CBs CPUs"
+	depends on RCU_NOCB_CPU
+	help
+	  This option does not force any of the CPUs to be no-CBs CPUs.
+	  Only CPUs designated by the rcu_nocbs= boot parameter will be
+	  no-CBs CPUs.
+
+config RCU_NOCB_CPU_ZERO
+	bool "CPU 0 is a build_forced no-CBs CPU"
+	depends on RCU_NOCB_CPU
+	help
+	  This option forces CPU 0 to be a no-CBs CPU.  Additional CPUs
+	  may be designated as no-CBs CPUs using the rcu_nocbs= boot
+	  parameter will be no-CBs CPUs.
+
+	  Select this if CPU 0 needs to be a no-CBs CPU for real-time
+	  or energy-efficiency reasons.
+
+config RCU_NOCB_CPU_ALL
+	bool "All CPUs are build_forced no-CBs CPUs"
+	depends on RCU_NOCB_CPU
+	help
+	  This option forces all CPUs to be no-CBs CPUs.  The rcu_nocbs=
+	  boot parameter will be ignored.
+
+	  Select this if all CPUs need to be no-CBs CPUs for real-time
+	  or energy-efficiency reasons.
+
+endchoice
+
 endmenu # "RCU Subsystem"
 
 config IKCONFIG
diff --git a/init/main.c b/init/main.c
index 2acb5bbde99b..1952bf2f6875 100644
--- a/init/main.c
+++ b/init/main.c
@@ -9,6 +9,8 @@
  *  Simplified starting of init:  Michael A. Griffith <grif@acm.org> 
  */
 
+#define DEBUG		/* Enable initcall_debug */
+
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/proc_fs.h>
@@ -174,8 +176,8 @@ static int __init obsolete_checksetup(char *line)
 				if (line[n] == '\0' || line[n] == '=')
 					had_early_param = 1;
 			} else if (!p->setup_func) {
-				printk(KERN_WARNING "Parameter %s is obsolete,"
-				       " ignored\n", p->str);
+				pr_warn("Parameter %s is obsolete, ignored\n",
+					p->str);
 				return 1;
 			} else if (p->setup_func(line + n))
 				return 1;
@@ -384,7 +386,7 @@ static noinline void __init_refok rest_init(void)
 	init_idle_bootup_task(current);
 	schedule_preempt_disabled();
 	/* Call into cpu_idle with preempt disabled */
-	cpu_idle();
+	cpu_startup_entry(CPUHP_ONLINE);
 }
 
 /* Check for early params. */
@@ -398,8 +400,7 @@ static int __init do_early_param(char *param, char *val, const char *unused)
 		     strcmp(p->str, "earlycon") == 0)
 		) {
 			if (p->setup_func(val) != 0)
-				printk(KERN_WARNING
-				       "Malformed early option '%s'\n", param);
+				pr_warn("Malformed early option '%s'\n", param);
 		}
 	}
 	/* We accept everything at this stage. */
@@ -497,7 +498,7 @@ asmlinkage void __init start_kernel(void)
 	tick_init();
 	boot_cpu_init();
 	page_address_init();
-	printk(KERN_NOTICE "%s", linux_banner);
+	pr_notice("%s", linux_banner);
 	setup_arch(&command_line);
 	mm_init_owner(&init_mm, &init_task);
 	mm_init_cpumask(&init_mm);
@@ -509,7 +510,7 @@ asmlinkage void __init start_kernel(void)
 	build_all_zonelists(NULL, NULL);
 	page_alloc_init();
 
-	printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
+	pr_notice("Kernel command line: %s\n", boot_command_line);
 	parse_early_param();
 	parse_args("Booting kernel", static_command_line, __start___param,
 		   __stop___param - __start___param,
@@ -539,11 +540,8 @@ asmlinkage void __init start_kernel(void)
 	 * fragile until we cpu_idle() for the first time.
 	 */
 	preempt_disable();
-	if (!irqs_disabled()) {
-		printk(KERN_WARNING "start_kernel(): bug: interrupts were "
-				"enabled *very* early, fixing it\n");
+	if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
 		local_irq_disable();
-	}
 	idr_init_cache();
 	perf_event_init();
 	rcu_init();
@@ -559,9 +557,7 @@ asmlinkage void __init start_kernel(void)
 	time_init();
 	profile_init();
 	call_function_init();
-	if (!irqs_disabled())
-		printk(KERN_CRIT "start_kernel(): bug: interrupts were "
-				 "enabled early\n");
+	WARN(!irqs_disabled(), "Interrupts were enabled early\n");
 	early_boot_irqs_disabled = false;
 	local_irq_enable();
 
@@ -588,8 +584,7 @@ asmlinkage void __init start_kernel(void)
 #ifdef CONFIG_BLK_DEV_INITRD
 	if (initrd_start && !initrd_below_start_ok &&
 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
-		printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
-		    "disabling it.\n",
+		pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
 		    page_to_pfn(virt_to_page((void *)initrd_start)),
 		    min_low_pfn);
 		initrd_start = 0;
@@ -668,14 +663,14 @@ static int __init_or_module do_one_initcall_debug(initcall_t fn)
 	unsigned long long duration;
 	int ret;
 
-	printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
+	pr_debug("calling  %pF @ %i\n", fn, task_pid_nr(current));
 	calltime = ktime_get();
 	ret = fn();
 	rettime = ktime_get();
 	delta = ktime_sub(rettime, calltime);
 	duration = (unsigned long long) ktime_to_ns(delta) >> 10;
-	printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
-		ret, duration);
+	pr_debug("initcall %pF returned %d after %lld usecs\n",
+		 fn, ret, duration);
 
 	return ret;
 }
@@ -703,9 +698,7 @@ int __init_or_module do_one_initcall(initcall_t fn)
 		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 		local_irq_enable();
 	}
-	if (msgbuf[0]) {
-		printk("initcall %pF returned with %s\n", fn, msgbuf);
-	}
+	WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
 
 	return ret;
 }
@@ -833,8 +826,7 @@ static int __ref kernel_init(void *unused)
 	if (ramdisk_execute_command) {
 		if (!run_init_process(ramdisk_execute_command))
 			return 0;
-		printk(KERN_WARNING "Failed to execute %s\n",
-				ramdisk_execute_command);
+		pr_err("Failed to execute %s\n", ramdisk_execute_command);
 	}
 
 	/*
@@ -846,8 +838,8 @@ static int __ref kernel_init(void *unused)
 	if (execute_command) {
 		if (!run_init_process(execute_command))
 			return 0;
-		printk(KERN_WARNING "Failed to execute %s.  Attempting "
-					"defaults...\n", execute_command);
+		pr_err("Failed to execute %s.  Attempting defaults...\n",
+			execute_command);
 	}
 	if (!run_init_process("/sbin/init") ||
 	    !run_init_process("/etc/init") ||
@@ -892,7 +884,7 @@ static noinline void __init kernel_init_freeable(void)
 
 	/* Open the /dev/console on the rootfs, this should never fail */
 	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
-		printk(KERN_WARNING "Warning: unable to open an initial console.\n");
+		pr_err("Warning: unable to open an initial console.\n");
 
 	(void) sys_dup(0);
 	(void) sys_dup(0);