From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue, 14 Apr 2015 20:36:04 +0000 (-0700)
Subject: Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git... 
X-Git-Tag: v4.1-rc1~145
X-Git-Url: https://git.kernelconcepts.de/?a=commitdiff_plain;h=078838d56574694d0a4815d9c1b7f28e8844638b;p=karo-tx-linux.git

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

Pull RCU changes from Ingo Molnar:
 "The main changes in this cycle were:

   - changes permitting use of call_rcu() and friends very early in
     boot, for example, before rcu_init() is invoked.

   - add in-kernel API to enable and disable expediting of normal RCU
     grace periods.

   - improve RCU's handling of (hotplug-) outgoing CPUs.

   - NO_HZ_FULL_SYSIDLE fixes.

   - tiny-RCU updates to make it more tiny.

   - documentation updates.

   - miscellaneous fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits)
  cpu: Provide smpboot_thread_init() on !CONFIG_SMP kernels as well
  cpu: Defer smpboot kthread unparking until CPU known to scheduler
  rcu: Associate quiescent-state reports with grace period
  rcu: Yet another fix for preemption and CPU hotplug
  rcu: Add diagnostics to grace-period cleanup
  rcutorture: Default to grace-period-initialization delays
  rcu: Handle outgoing CPUs on exit from idle loop
  cpu: Make CPU-offline idle-loop transition point more precise
  rcu: Eliminate ->onoff_mutex from rcu_node structure
  rcu: Process offlining and onlining only at grace-period start
  rcu: Move rcu_report_unblock_qs_rnp() to common code
  rcu: Rework preemptible expedited bitmask handling
  rcu: Remove event tracing from rcu_cpu_notify(), used by offline CPUs
  rcutorture: Enable slow grace-period initializations
  rcu: Provide diagnostic option to slow down grace-period initialization
  rcu: Detect stalls caused by failure to propagate up rcu_node tree
  rcu: Eliminate empty HOTPLUG_CPU ifdef
  rcu: Simplify sync_rcu_preempt_exp_init()
  rcu: Put all orphan-callback-related code under same comment
  rcu: Consolidate offline-CPU callback initialization
  ...
---

078838d56574694d0a4815d9c1b7f28e8844638b
diff --cc arch/x86/include/asm/smp.h
index 81d02fc7dafa,a5cb4f6e9492..17a8dced12da
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@@ -153,10 -153,9 +153,10 @@@ void cpu_disable_common(void)
  void native_smp_prepare_boot_cpu(void);
  void native_smp_prepare_cpus(unsigned int max_cpus);
  void native_smp_cpus_done(unsigned int max_cpus);
 +void common_cpu_up(unsigned int cpunum, struct task_struct *tidle);
  int native_cpu_up(unsigned int cpunum, struct task_struct *tidle);
  int native_cpu_disable(void);
+ int common_cpu_die(unsigned int cpu);
  void native_cpu_die(unsigned int cpu);
  void native_play_dead(void);
  void play_dead_common(void);
diff --cc kernel/cpu.c
index 82eea9c5af61,57858cebd6b5..94bbe4695232
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@@ -411,10 -408,11 +411,12 @@@ static int __ref _cpu_down(unsigned in
  	 *
  	 * Wait for the stop thread to go away.
  	 */
- 	while (!idle_cpu(cpu))
+ 	while (!per_cpu(cpu_dead_idle, cpu))
  		cpu_relax();
+ 	smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */
+ 	per_cpu(cpu_dead_idle, cpu) = false;
  
 +	hotplug_cpu__broadcast_tick_pull(cpu);
  	/* This actually kills the CPU. */
  	__cpu_die(cpu);