rcu: Use smp_hotplug_thread facility for RCUs per-CPU kthread

Bring RCU into the new-age CPU-hotplug fold by modifying RCU's per-CPU
kthread code to use the new smp_hotplug_thread facility.

[ tglx: Adapted it to use callbacks and to the simplified rcu yield ]
    
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20120716103948.673354828@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 0 insertions, 4 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index f08ee3bc5741..11a4fdca1df7 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -133,7 +133,6 @@ static int rcu_scheduler_fully_active __read_mostly;
  */
 static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
 DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
-DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu);
 DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
 DEFINE_PER_CPU(char, rcu_cpu_has_work);
 
@@ -1468,7 +1467,6 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
         struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
 
         /* Adjust any no-longer-needed kthreads. */
-        rcu_stop_cpu_kthread(cpu);
         rcu_boost_kthread_setaffinity(rnp, -1);
 
         /* Remove the dead CPU from the bitmasks in the rcu_node hierarchy. */
@@ -2595,11 +2593,9 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
         case CPU_ONLINE:
         case CPU_DOWN_FAILED:
                 rcu_boost_kthread_setaffinity(rnp, -1);
-                rcu_cpu_kthread_setrt(cpu, 1);
                 break;
         case CPU_DOWN_PREPARE:
                 rcu_boost_kthread_setaffinity(rnp, cpu);
-                rcu_cpu_kthread_setrt(cpu, 0);
                 break;
         case CPU_DYING:
         case CPU_DYING_FROZEN: