Merge tag 'rcu.release.v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Neeraj Upadhyay:
 "Context tracking:
   - rename context tracking state related symbols and remove references
     to "dynticks" in various context tracking state variables and
     related helpers
   - force context_tracking_enabled_this_cpu() to be inlined to avoid
     leaving a noinstr section

  CSD lock:
   - enhance CSD-lock diagnostic reports
   - add an API to provide an indication of ongoing CSD-lock stall

  nocb:
   - update and simplify RCU nocb code to handle (de-)offloading of
     callbacks only for offline CPUs
   - fix RT throttling hrtimer being armed from offline CPU

  rcutorture:
   - remove redundant rcu_torture_ops get_gp_completed fields
   - add SRCU ->same_gp_state and ->get_comp_state functions
   - add generic test for NUM_ACTIVE_*RCU_POLL* for testing RCU and SRCU
     polled grace periods
   - add CFcommon.arch for arch-specific Kconfig options
   - print number of update types in rcu_torture_write_types()
   - add rcutree.nohz_full_patience_delay testing to the TREE07 scenario
   - add a stall_cpu_repeat module parameter to test repeated CPU stalls
   - add argument to limit number of CPUs a guest OS can use in
     torture.sh

  rcustall:
   - abbreviate RCU CPU stall warnings during CSD-lock stalls
   - Allow dump_cpu_task() to be called without disabling preemption
   - defer printing stall-warning backtrace when holding rcu_node lock

  srcu:
   - make SRCU gp seq wrap-around faster
   - add KCSAN checks for concurrent updates to ->srcu_n_exp_nodelay and
     ->reschedule_count which are used in heuristics governing
     auto-expediting of normal SRCU grace periods and
     grace-period-state-machine delays
   - mark idle SRCU-barrier callbacks to help identify stuck
     SRCU-barrier callback

  rcu tasks:
   - remove RCU Tasks Rude asynchronous APIs as they are no longer used
   - stop testing RCU Tasks Rude asynchronous APIs
   - fix access to non-existent percpu regions
   - check processor-ID assumptions during chosen CPU calculation for
     callback enqueuing
   - update description of rtp->tasks_gp_seq grace-period sequence
     number
   - add rcu_barrier_cb_is_done() to identify whether a given
     rcu_barrier callback is stuck
   - mark idle Tasks-RCU-barrier callbacks
   - add *torture_stats_print() functions to print detailed diagnostics
     for Tasks-RCU variants
   - capture start time of rcu_barrier_tasks*() operation to help
     distinguish a hung barrier operation from a long series of barrier
     operations

  refscale:
   - add a TINY scenario to support tests of Tiny RCU and Tiny
     SRCU
   - optimize process_durations() operation

  rcuscale:
   - dump stacks of stalled rcu_scale_writer() instances and
     grace-period statistics when rcu_scale_writer() stalls
   - mark idle RCU-barrier callbacks to identify stuck RCU-barrier
     callbacks
   - print detailed grace-period and barrier diagnostics on
     rcu_scale_writer() hangs for Tasks-RCU variants
   - warn if async module parameter is specified for RCU implementations
     that do not have async primitives such as RCU Tasks Rude
   - make all writer tasks report upon hang
   - tolerate repeated GFP_KERNEL failure in rcu_scale_writer()
   - use special allocator for rcu_scale_writer()
   - NULL out top-level pointers to heap memory to avoid double-free
     bugs on modprobe failures
   - maintain per-task instead of per-CPU callbacks count to avoid any
     issues with migration of either tasks or callbacks
   - constify struct ref_scale_ops

  Fixes:
   - use system_unbound_wq for kfree_rcu work to avoid disturbing
     isolated CPUs

  Misc:
   - warn on unexpected rcu_state.srs_done_tail state
   - better define "atomic" for list_replace_rcu() and
     hlist_replace_rcu() routines
   - annotate struct kvfree_rcu_bulk_data with __counted_by()"

* tag 'rcu.release.v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (90 commits)
  rcu: Defer printing stall-warning backtrace when holding rcu_node lock
  rcu/nocb: Remove superfluous memory barrier after bypass enqueue
  rcu/nocb: Conditionally wake up rcuo if not already waiting on GP
  rcu/nocb: Fix RT throttling hrtimer armed from offline CPU
  rcu/nocb: Simplify (de-)offloading state machine
  context_tracking: Tag context_tracking_enabled_this_cpu() __always_inline
  context_tracking, rcu: Rename rcu_dyntick trace event into rcu_watching
  rcu: Update stray documentation references to rcu_dynticks_eqs_{enter, exit}()
  rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs()
  rcu: Rename rcu_implicit_dynticks_qs() into rcu_watching_snap_recheck()
  rcu: Rename dyntick_save_progress_counter() into rcu_watching_snap_save()
  rcu: Rename struct rcu_data .exp_dynticks_snap into .exp_watching_snap
  rcu: Rename struct rcu_data .dynticks_snap into .watching_snap
  rcu: Rename rcu_dynticks_zero_in_eqs() into rcu_watching_zero_in_eqs()
  rcu: Rename rcu_dynticks_in_eqs_since() into rcu_watching_snap_stopped_since()
  rcu: Rename rcu_dynticks_in_eqs() into rcu_watching_snap_in_eqs()
  rcu: Rename rcu_dynticks_eqs_online() into rcu_watching_online()
  context_tracking, rcu: Rename rcu_dynticks_curr_cpu_in_eqs() into rcu_is_watching_curr_cpu()
  context_tracking, rcu: Rename rcu_dynticks_task*() into rcu_task*()
  refscale: Constify struct ref_scale_ops
  ...

1 files changed, 18 insertions, 14 deletions

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 8a78fabeafc3..af9fe87a0922 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -26,26 +26,26 @@ extern void user_exit_callable(void);
 static inline void user_enter(void)
 {
 	if (context_tracking_enabled())
-		ct_user_enter(CONTEXT_USER);
+		ct_user_enter(CT_STATE_USER);
 
 }
 static inline void user_exit(void)
 {
 	if (context_tracking_enabled())
-		ct_user_exit(CONTEXT_USER);
+		ct_user_exit(CT_STATE_USER);
 }
 
 /* Called with interrupts disabled.  */
 static __always_inline void user_enter_irqoff(void)
 {
 	if (context_tracking_enabled())
-		__ct_user_enter(CONTEXT_USER);
+		__ct_user_enter(CT_STATE_USER);
 
 }
 static __always_inline void user_exit_irqoff(void)
 {
 	if (context_tracking_enabled())
-		__ct_user_exit(CONTEXT_USER);
+		__ct_user_exit(CT_STATE_USER);
 }
 
 static inline enum ctx_state exception_enter(void)
@@ -57,7 +57,7 @@ static inline enum ctx_state exception_enter(void)
 		return 0;
 
 	prev_ctx = __ct_state();
-	if (prev_ctx != CONTEXT_KERNEL)
+	if (prev_ctx != CT_STATE_KERNEL)
 		ct_user_exit(prev_ctx);
 
 	return prev_ctx;
@@ -67,7 +67,7 @@ static inline void exception_exit(enum ctx_state prev_ctx)
 {
 	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) &&
 	    context_tracking_enabled()) {
-		if (prev_ctx != CONTEXT_KERNEL)
+		if (prev_ctx != CT_STATE_KERNEL)
 			ct_user_enter(prev_ctx);
 	}
 }
@@ -75,7 +75,7 @@ static inline void exception_exit(enum ctx_state prev_ctx)
 static __always_inline bool context_tracking_guest_enter(void)
 {
 	if (context_tracking_enabled())
-		__ct_user_enter(CONTEXT_GUEST);
+		__ct_user_enter(CT_STATE_GUEST);
 
 	return context_tracking_enabled_this_cpu();
 }
@@ -83,7 +83,7 @@ static __always_inline bool context_tracking_guest_enter(void)
 static __always_inline bool context_tracking_guest_exit(void)
 {
 	if (context_tracking_enabled())
-		__ct_user_exit(CONTEXT_GUEST);
+		__ct_user_exit(CT_STATE_GUEST);
 
 	return context_tracking_enabled_this_cpu();
 }
@@ -115,13 +115,17 @@ extern void ct_idle_enter(void);
 extern void ct_idle_exit(void);
 
 /*
- * Is the current CPU in an extended quiescent state?
+ * Is RCU watching the current CPU (IOW, it is not in an extended quiescent state)?
+ *
+ * Note that this returns the actual boolean data (watching / not watching),
+ * whereas ct_rcu_watching() returns the RCU_WATCHING subvariable of
+ * context_tracking.state.
  *
  * No ordering, as we are sampling CPU-local information.
  */
-static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
+static __always_inline bool rcu_is_watching_curr_cpu(void)
 {
-	return !(raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & RCU_DYNTICKS_IDX);
+	return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_RCU_WATCHING;
 }
 
 /*
@@ -142,9 +146,9 @@ static __always_inline bool warn_rcu_enter(void)
 	 * lots of the actual reporting also relies on RCU.
 	 */
 	preempt_disable_notrace();
-	if (rcu_dynticks_curr_cpu_in_eqs()) {
+	if (!rcu_is_watching_curr_cpu()) {
 		ret = true;
-		ct_state_inc(RCU_DYNTICKS_IDX);
+		ct_state_inc(CT_RCU_WATCHING);
 	}
 
 	return ret;
@@ -153,7 +157,7 @@ static __always_inline bool warn_rcu_enter(void)
 static __always_inline void warn_rcu_exit(bool rcu)
 {
 	if (rcu)
-		ct_state_inc(RCU_DYNTICKS_IDX);
+		ct_state_inc(CT_RCU_WATCHING);
 	preempt_enable_notrace();
 }