kernel/linux.git/Documentation/RCU/Design/Requirements, branch v6.19.11

doc: Update for SRCU-fast definitions and initialization

2025-11-05T22:58:30+00:00

This commit documents the DEFINE_SRCU_FAST(), DEFINE_STATIC_SRCU_FAST(), and init_srcu_struct_fast() API members. Signed-off-by: Paul E. McKenney Cc: Mathieu Desnoyers Cc: Steven Rostedt Cc: Sebastian Andrzej Siewior Cc: Signed-off-by: Frederic Weisbecker

rcu: docs: Requirements.rst: Abide by conventions of kernel documentation

2025-08-20T18:51:28+00:00

Here is a list of conventions applied here: - Don't mark up function names, to be taken care of by the automarkup extension. Just say func(). - Instead of ".. code-block:: none", just say "::". - Mark inline literals by a pair of ``xxxx``. Don't use rust doc's dialect of `yyyy`. - Instead of emphasizing headings by **strong emphasis**, use sub-level title adornments, in this case "^^^^^^^^^^" and make them proper sub-sections under "Hotplug CPU". Signed-off-by: Akira Yokosawa Cc: Joel Fernandes Signed-off-by: Neeraj Upadhyay (AMD) Signed-off-by: Paul E. McKenney

rcu: Document concurrent quiescent state reporting for offline CPUs

2025-07-22T11:40:50+00:00

The synchronization of CPU offlining with GP initialization is confusing to put it mildly (rightfully so as the issue it deals with is complex). Recent discussions brought up a question -- what prevents the rcu_implicit_dyntick_qs() from warning about QS reports for offline CPUs (missing QS reports for offline CPUs causing indefinite hangs). QS reporting for now-offline CPUs should only happen from: - gp_init() - rcutree_cpu_report_dead() Add some documentation on this and refer to it from comments in the code explaining how QS reporting is not missed when these functions are concurrently running. I referred heavily to this post [1] about the need for the ofl_lock. [1] https://lore.kernel.org/all/20180924164443.GF4222@linux.ibm.com/ [ Applied paulmck feedback on moving documentation to Requirements.rst ] Link: https://lore.kernel.org/all/01b4d228-9416-43f8-a62e-124b92e8741a@paulmck-laptop/ Co-developed-by: "Paul E. McKenney" Signed-off-by: "Paul E. McKenney" Reviewed-by: Frederic Weisbecker Signed-off-by: Joel Fernandes Signed-off-by: Neeraj Upadhyay (AMD)

rcu: Document GP init vs hotplug-scan ordering requirements

2025-07-22T11:39:35+00:00

Add detailed comments explaining the critical ordering constraints during RCU grace period initialization, based on discussions with Frederic. Reviewed-by: "Paul E. McKenney" Co-developed-by: Frederic Weisbecker Signed-off-by: Frederic Weisbecker Signed-off-by: Joel Fernandes Signed-off-by: Neeraj Upadhyay (AMD)

doc: Remove RCU Tasks Rude asynchronous APIs

2024-08-14T11:15:07+00:00

The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are no longer. This commit therefore removes them from the documentation. Signed-off-by: Paul E. McKenney Signed-off-by: Neeraj Upadhyay

doc: Update Tasks RCU and Tasks Rude RCU description in Requirements.rst

2024-06-06T18:32:04+00:00

This commit adds more detail to the Tasks RCU and Tasks Rude RCU descriptions in Requirements.rst. While in the area, add Tasks Trace RCU to the Tasks-RCU table of contents. Reported-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney Reviewed-by: Frederic Weisbecker

rcu: Standardize explicit CPU-hotplug calls

2023-10-04T20:29:45+00:00

rcu_report_dead() and rcutree_migrate_callbacks() have their headers in rcupdate.h while those are pure rcutree calls, like the other CPU-hotplug functions. Also rcu_cpu_starting() and rcu_report_dead() have different naming conventions while they mirror each other's effects. Fix the headers and propose a naming that relates both functions and aligns with the prefix of other rcutree CPU-hotplug functions. Reviewed-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker

rcu: Remove RCU_NONIDLE()

2023-05-11T20:42:04+00:00

Since there are now exactly _zero_ users of RCU_NONIDLE(), make it go away before someone else decides to (ab)use it. [ paulmck: Remove extraneous whitespace. ] Signed-off-by: Peter Zijlstra (Intel) Acked-by: Mark Rutland Acked-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney

timers: Update the documentation to reflect on the new timer_shutdown() API

2022-11-24T14:09:12+00:00

In order to make sure that a timer is not re-armed after it is stopped before freeing, a new shutdown state is added to the timer code. The API timer_shutdown_sync() and timer_shutdown() must be called before the object that holds the timer can be freed. Update the documentation to reflect this new workflow. [ tglx: Updated to the new semantics and updated the zh_CN version ] Signed-off-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Reviewed-by: Jacob Keller Reviewed-by: Anna-Maria Behnsen Link: https://lore.kernel.org/r/20221110064147.712934793@goodmis.org Link: https://lore.kernel.org/r/20221123201625.375284489@linutronix.de

Documentation: Replace del_timer/del_timer_sync()

2022-11-24T14:09:11+00:00

Adjust to the new preferred function names. Suggested-by: Steven Rostedt Signed-off-by: Thomas Gleixner Reviewed-by: Jacob Keller Reviewed-by: Anna-Maria Behnsen Link: https://lore.kernel.org/r/20221123201625.075320635@linutronix.de