idle-related changes

Hello!

This series handles changes to the interaction between RCU and idle, including adaptive ticks. Almost all of these patches are courtesy of Frederic Weisbecker. The patches are as follows:

1. Allow non-idle tasks to enter dyntick-idle mode from RCU's
perspective in order to enable adaptive ticks.
2. Add rcu_user_enter_irq() and rcu_user_exit_irq() to enable
switching into and out of dyntick-idle mode in interrupt handlers to handle wakeups.
3. Modify RCU_FAST_NO_HZ to accommodate adaptive ticks.
4. Add a Kconfig option to enable extended quiescent states while
in usermode execution.
5. Allow multiple rcu_user_enter() calls to match an rcu_user_exit().
6. Introcude runtime control for RCU's classification of user-mode
execution as an extended quiescent state.
7. Update adaptive-tick state on context switch in order to handle
task migration.
8. On x86, notify RCU of slowpath syscall entry to and exit from
usermode execution so that RCU can track the resulting extended quiescent states.
9. On c86, notify RCU of exception-path entry to and exit from
usermode execution so that RCU can again strack the resulting extended quiescent states.
10. Exit RCU extended QS on kernel preemption after irq/exception.
11. Exit RCU extended QS on user preemption.
12. On x86, use the new schedule_user API on userspace preemption.
13. On x86, exit RCU extended QS on notify resumes.
14. Provide a new RCU_USER_QS_FORCE kconfig option that enables
userspace RCU extended quiescent states on all CPUs for testing purposes.
15-26. Fix idle-loop breakage introduced on 3.3. This affects all
architectures that do not implement NO_HZ.

Thanx, Paul

------------------------------------------------------------------------

 arch/alpha/kernel/process.c          |    3 
 b/arch/Kconfig                       |   10 +++
 b/arch/alpha/kernel/process.c        |    3 
 b/arch/alpha/kernel/smp.c            |    1 
 b/arch/cris/kernel/process.c         |    3 
 b/arch/frv/kernel/process.c          |    3 
 b/arch/h8300/kernel/process.c        |    3 
 b/arch/ia64/kernel/process.c         |    3 
 b/arch/m32r/kernel/process.c         |    3 
 b/arch/m68k/kernel/process.c         |    3 
 b/arch/mn10300/kernel/process.c      |    3 
 b/arch/parisc/kernel/process.c       |    3 
 b/arch/score/kernel/process.c        |    4 -
 b/arch/um/drivers/mconsole_kern.c    |    1 
 b/arch/x86/Kconfig                   |    1 
 b/arch/x86/include/asm/rcu.h         |   20 ++++++
 b/arch/x86/include/asm/thread_info.h |   10 ++-
 b/arch/x86/kernel/entry_64.S         |    8 +-
 b/arch/x86/kernel/ptrace.c           |    5 +
 b/arch/x86/kernel/signal.c           |    4 +
 b/arch/x86/kernel/traps.c            |   30 ++++++---
 b/arch/x86/mm/fault.c                |   13 +++
 b/arch/xtensa/kernel/process.c       |    3 
 b/include/linux/rcupdate.h           |    2 
 b/include/linux/sched.h              |    8 ++
 b/init/Kconfig                       |   10 +++
 b/kernel/rcutree.c                   |  115 ++++++++++++++++++++++++-----------
 b/kernel/rcutree.h                   |    3 
 b/kernel/rcutree_plugin.h            |   20 ++++++
 b/kernel/sched/core.c                |    1 
 include/linux/rcupdate.h             |   12 +++
 init/Kconfig                         |    8 ++
 kernel/rcutree.c                     |  111 ++++++++++++++++++++++++++++++---
 kernel/rcutree.h                     |    1 
 kernel/sched/core.c                  |    8 ++
 35 files changed, 375 insertions(+), 64 deletions(-)