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);