[PATCH v2 00/10] Make RCU Tasks scan idle tasks

[neeraj . upadhyay]

From: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>

Architectures for which all deep-idle and entry-exit functions are
marked noinstr, synchronize_rcu_tasks_rude() is not required. However,
disabling synchronize_rcu_tasks_rude() for such architectures require
RCU-tasks to pay attention to idle tasks until they enter the context
where RCU is not watching. In addition, NMI context need to track RCU-tasks
entry/exit for NO_HZ_FULL CPUs. This series adds changes for both of
these requirements.

The series is available in git tree at:

https://git.kernel.org/pub/scm/linux/kernel/git/neeraj.upadhyay/linux-rcu.git/log/?h=rcu.tasks.idle

Changes since v1: https://lore.kernel.org/lkml/20240807163506.434885-1-neeraj.upadhyay@xxxxxxxxxx/

- Split into multiple patches (Paul)
- Various restructuring updates (Frederic)
- Fix race with early boot code (Frederic)
- Check RCU watching state for idle injection tasks.
- Include patch to turn synchronize_rcu_tasks_rude() into noop
  for architectures with CONFIG_ARCH_WANTS_NO_INSTR enabled.

Neeraj Upadhyay (9):
  rcu: Change rdp arg to cpu number for
    rcu_watching_snap_stopped_since()
  rcu: Make some rcu_watching_* functions global
  rcu/tasks: Move holdout checks for idle task to a separate function
  rcu/tasks: Create rcu_idle_task_is_holdout() definition for !SMP
  rcu/tasks: Consider idle tasks not running on CPU as non-holdouts
  rcu/tasks: Check RCU watching state for holdout idle tasks
  rcu/tasks: Check RCU watching state for holdout idle injection tasks
  rcu/tasks: Make RCU-tasks pay attention to idle tasks
  context_tracking: Invoke RCU-tasks enter/exit for NMI context

Paul E. McKenney (1):
  rcu: Allow short-circuiting of synchronize_rcu_tasks_rude()

 .../RCU/Design/Requirements/Requirements.rst  |  12 +-
 kernel/context_tracking.c                     |  11 +-
 kernel/rcu/rcu.h                              |   4 +
 kernel/rcu/tasks.h                            | 148 ++++++++++++++----
 kernel/rcu/tree.c                             |  16 +-
 kernel/rcu/tree_exp.h                         |   2 +-
 6 files changed, 140 insertions(+), 53 deletions(-)

-- 
2.40.1