context_tracking, rcu: Rename rcu_dynticks_task*() into rcu_task*()

The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.

While at it, flip the suffixes of these helpers. We are not telling
that we are entering dynticks mode from an RCU-task perspective anymore; we
are telling that we are exiting RCU-tasks because we are in eqs mode.

[ neeraj.upadhyay: Incorporate Frederic Weisbecker feedback. ]
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>

kernel/context_tracking.c

@@ -38,24 +38,24 @@ EXPORT_SYMBOL_GPL(context_tracking);
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 #define TPS(x)  tracepoint_string(x)
 
-/* Record the current task on dyntick-idle entry. */
-static __always_inline void rcu_dynticks_task_enter(void)
+/* Record the current task on exiting RCU-tasks (dyntick-idle entry). */
+static __always_inline void rcu_task_exit(void)
 {
 #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
 	WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id());
 #endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
 }
 
-/* Record no current task on dyntick-idle exit. */
-static __always_inline void rcu_dynticks_task_exit(void)
+/* Record no current task on entering RCU-tasks (dyntick-idle exit). */
+static __always_inline void rcu_task_enter(void)
 {
 #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
 	WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);
 #endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
 }
 
-/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */
-static __always_inline void rcu_dynticks_task_trace_enter(void)
+/* Turn on heavyweight RCU tasks trace readers on kernel exit. */
+static __always_inline void rcu_task_trace_heavyweight_enter(void)
 {
 #ifdef CONFIG_TASKS_TRACE_RCU
 	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
@@ -63,8 +63,8 @@ static __always_inline void rcu_dynticks_task_trace_enter(void)
 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
 }
 
-/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */
-static __always_inline void rcu_dynticks_task_trace_exit(void)
+/* Turn off heavyweight RCU tasks trace readers on kernel entry. */
+static __always_inline void rcu_task_trace_heavyweight_exit(void)
 {
 #ifdef CONFIG_TASKS_TRACE_RCU
 	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
@@ -87,7 +87,7 @@ static noinstr void ct_kernel_exit_state(int offset)
 	 * critical sections, and we also must force ordering with the
 	 * next idle sojourn.
 	 */
-	rcu_dynticks_task_trace_enter();  // Before ->dynticks update!
+	rcu_task_trace_heavyweight_enter();  // Before CT state update!
 	seq = ct_state_inc(offset);
 	// RCU is no longer watching.  Better be in extended quiescent state!
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & CT_RCU_WATCHING));
@@ -109,7 +109,7 @@ static noinstr void ct_kernel_enter_state(int offset)
 	 */
 	seq = ct_state_inc(offset);
 	// RCU is now watching.  Better not be in an extended quiescent state!
-	rcu_dynticks_task_trace_exit();  // After ->dynticks update!
+	rcu_task_trace_heavyweight_exit();  // After CT state update!
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & CT_RCU_WATCHING));
 }
 
@@ -149,7 +149,7 @@ static void noinstr ct_kernel_exit(bool user, int offset)
 	// RCU is watching here ...
 	ct_kernel_exit_state(offset);
 	// ... but is no longer watching here.
-	rcu_dynticks_task_enter();
+	rcu_task_exit();
 }
 
 /*
@@ -173,7 +173,7 @@ static void noinstr ct_kernel_enter(bool user, int offset)
 		ct->nesting++;
 		return;
 	}
-	rcu_dynticks_task_exit();
+	rcu_task_enter();
 	// RCU is not watching here ...
 	ct_kernel_enter_state(offset);
 	// ... but is watching here.
@@ -240,7 +240,7 @@ void noinstr ct_nmi_exit(void)
 	// ... but is no longer watching here.
 
 	if (!in_nmi())
-		rcu_dynticks_task_enter();
+		rcu_task_exit();
 }
 
 /**
@@ -274,7 +274,7 @@ void noinstr ct_nmi_enter(void)
 	if (rcu_dynticks_curr_cpu_in_eqs()) {
 
 		if (!in_nmi())
-			rcu_dynticks_task_exit();
+			rcu_task_enter();
 
 		// RCU is not watching here ...
 		ct_kernel_enter_state(CT_RCU_WATCHING);