[16/23] rcu/context_tracking: Move dynticks_nmi_nesting to context tracking

Commit Message

Paul E. McKenney June 20, 2022, 11:10 p.m. UTC

From: Frederic Weisbecker <[e-mail]>

The RCU eqs tracking is going to be performed by the context tracking
subsystem. The related nesting counters thus need to be moved to the
context tracking structure.

Signed-off-by: Frederic Weisbecker <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Neeraj Upadhyay <[e-mail]>
Cc: Uladzislau Rezki <[e-mail]>
Cc: Joel Fernandes <[e-mail]>
Cc: Boqun Feng <[e-mail]>
Cc: Nicolas Saenz Julienne <[e-mail]>
Cc: Marcelo Tosatti <[e-mail]>
Cc: Xiongfeng Wang <[e-mail]>
Cc: Yu Liao <[e-mail]>
Cc: Phil Auld <[e-mail]>
Cc: Paul Gortmaker<[e-mail]>
Cc: Alex Belits <[e-mail]>
Signed-off-by: Paul E. McKenney <[e-mail]>
---
 include/linux/context_tracking_state.h | 15 ++++++++
 kernel/context_tracking.c              |  1 +
 kernel/rcu/rcu.h                       |  4 ---
 kernel/rcu/tree.c                      | 48 +++++++++++---------------
 kernel/rcu/tree.h                      |  1 -
 kernel/rcu/tree_stall.h                |  2 +-
 6 files changed, 38 insertions(+), 33 deletions(-)

Patch

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index c866701c7edb5..2f957b48e24f9 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -13,6 +13,9 @@  enum ctx_state {
 	CONTEXT_GUEST,
 };
 
+/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
+#define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
+
 struct context_tracking {
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 	/*
@@ -28,6 +31,7 @@  struct context_tracking {
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	atomic_t dynticks;		/* Even value for idle, else odd. */
 	long dynticks_nesting;		/* Track process nesting level. */
+	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
 #endif
 };
 
@@ -63,6 +67,17 @@  static __always_inline long ct_dynticks_nesting_cpu(int cpu)
 	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
 	return ct->dynticks_nesting;
 }
+
+static __always_inline long ct_dynticks_nmi_nesting(void)
+{
+	return __this_cpu_read(context_tracking.dynticks_nmi_nesting);
+}
+
+static __always_inline long ct_dynticks_nmi_nesting_cpu(int cpu)
+{
+	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+	return ct->dynticks_nmi_nesting;
+}
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
 #ifdef CONFIG_CONTEXT_TRACKING_USER
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index ed6c062aff9fa..bf5f498b21d39 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -26,6 +26,7 @@ 
 DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	.dynticks_nesting = 1,
+	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
 	.dynticks = ATOMIC_INIT(1),
 #endif
 };
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 4916077119f3f..7b4a88deff9ad 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -12,10 +12,6 @@ 
 
 #include <trace/events/rcu.h>
 
-/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
-#define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
-
-
 /*
  * Grace-period counter management.
  */
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f6bf328bb9cfd..006939b29e823 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -75,7 +75,6 @@ 
 /* Data structures. */
 
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
-	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
 #ifdef CONFIG_RCU_NOCB_CPU
 	.cblist.flags = SEGCBLIST_RCU_CORE,
 #endif
@@ -437,11 +436,11 @@  static int rcu_is_cpu_rrupt_from_idle(void)
 	/* Check for counter underflows */
 	RCU_LOCKDEP_WARN(ct_dynticks_nesting() < 0,
 			 "RCU dynticks_nesting counter underflow!");
-	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0,
+	RCU_LOCKDEP_WARN(ct_dynticks_nmi_nesting() <= 0,
 			 "RCU dynticks_nmi_nesting counter underflow/zero!");
 
 	/* Are we at first interrupt nesting level? */
-	nesting = __this_cpu_read(rcu_data.dynticks_nmi_nesting);
+	nesting = ct_dynticks_nmi_nesting();
 	if (nesting > 1)
 		return false;
 
@@ -612,11 +611,10 @@  EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
  */
 static noinstr void rcu_eqs_enter(bool user)
 {
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() != DYNTICK_IRQ_NONIDLE);
+	WRITE_ONCE(ct->dynticks_nmi_nesting, 0);
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
 		     ct_dynticks_nesting() == 0);
 	if (ct_dynticks_nesting() != 1) {
@@ -734,7 +732,7 @@  noinstr void rcu_user_enter(void)
  * rcu_nmi_exit - inform RCU of exit from NMI context
  *
  * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update ct->dynticks and rdp->dynticks_nmi_nesting
+ * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
@@ -744,7 +742,6 @@  noinstr void rcu_user_enter(void)
 noinstr void rcu_nmi_exit(void)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 
 	instrumentation_begin();
 	/*
@@ -752,25 +749,25 @@  noinstr void rcu_nmi_exit(void)
 	 * (We are exiting an NMI handler, so RCU better be paying attention
 	 * to us!)
 	 */
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting <= 0);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() <= 0);
 	WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
 
 	/*
 	 * If the nesting level is not 1, the CPU wasn't RCU-idle, so
 	 * leave it in non-RCU-idle state.
 	 */
-	if (rdp->dynticks_nmi_nesting != 1) {
-		trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2,
+	if (ct_dynticks_nmi_nesting() != 1) {
+		trace_rcu_dyntick(TPS("--="), ct_dynticks_nmi_nesting(), ct_dynticks_nmi_nesting() - 2,
 				  ct_dynticks());
-		WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
-			   rdp->dynticks_nmi_nesting - 2);
+		WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */
+			   ct_dynticks_nmi_nesting() - 2);
 		instrumentation_end();
 		return;
 	}
 
 	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-	trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, ct_dynticks());
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
+	trace_rcu_dyntick(TPS("Startirq"), ct_dynticks_nmi_nesting(), 0, ct_dynticks());
+	WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 
 	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
 	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
@@ -794,7 +791,7 @@  void rcu_irq_exit_check_preempt(void)
 
 	RCU_LOCKDEP_WARN(ct_dynticks_nesting() <= 0,
 			 "RCU dynticks_nesting counter underflow/zero!");
-	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=
+	RCU_LOCKDEP_WARN(ct_dynticks_nmi_nesting() !=
 			 DYNTICK_IRQ_NONIDLE,
 			 "Bad RCU  dynticks_nmi_nesting counter\n");
 	RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(),
@@ -813,11 +810,9 @@  void rcu_irq_exit_check_preempt(void)
 static void noinstr rcu_eqs_exit(bool user)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-	struct rcu_data *rdp;
 	long oldval;
 
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
-	rdp = this_cpu_ptr(&rcu_data);
 	oldval = ct_dynticks_nesting();
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
 	if (oldval) {
@@ -837,8 +832,8 @@  static void noinstr rcu_eqs_exit(bool user)
 	trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	WRITE_ONCE(ct->dynticks_nesting, 1);
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting());
+	WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
 	instrumentation_end();
 }
 
@@ -941,7 +936,7 @@  void __rcu_irq_enter_check_tick(void)
  * rcu_nmi_enter - inform RCU of entry to NMI context
  *
  * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
- * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know
+ * ct->dynticks_nmi_nesting to let the RCU grace-period handling know
  * that the CPU is active.  This implementation permits nested NMIs, as
  * long as the nesting level does not overflow an int.  (You will probably
  * run out of stack space first.)
@@ -952,11 +947,10 @@  void __rcu_irq_enter_check_tick(void)
 noinstr void rcu_nmi_enter(void)
 {
 	long incby = 2;
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
 	/* Complain about underflow. */
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() < 0);
 
 	/*
 	 * If idle from RCU viewpoint, atomically increment ->dynticks
@@ -990,11 +984,11 @@  noinstr void rcu_nmi_enter(void)
 	}
 
 	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
-			  rdp->dynticks_nmi_nesting,
-			  rdp->dynticks_nmi_nesting + incby, ct_dynticks());
+			  ct_dynticks_nmi_nesting(),
+			  ct_dynticks_nmi_nesting() + incby, ct_dynticks());
 	instrumentation_end();
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
-		   rdp->dynticks_nmi_nesting + incby);
+	WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */
+		   ct_dynticks_nmi_nesting() + incby);
 	barrier();
 }
 
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 650ff3cf01219..72dbf8512ce78 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -187,7 +187,6 @@  struct rcu_data {
 
 	/* 3) dynticks interface. */
 	int dynticks_snap;		/* Per-GP tracking for dynticks. */
-	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
 	bool rcu_need_heavy_qs;		/* GP old, so heavy quiescent state! */
 	bool rcu_urgent_qs;		/* GP old need light quiescent state. */
 	bool rcu_forced_tick;		/* Forced tick to provide QS. */
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index a9c82254b6c65..2683ce0a7c724 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -479,7 +479,7 @@  static void print_cpu_stall_info(int cpu)
 				"!."[!delta],
 	       ticks_value, ticks_title,
 	       rcu_dynticks_snap(cpu) & 0xfff,
-	       ct_dynticks_nesting_cpu(cpu), rdp->dynticks_nmi_nesting,
+	       ct_dynticks_nesting_cpu(cpu), ct_dynticks_nmi_nesting_cpu(cpu),
 	       rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
 	       data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
 	       rcuc_starved ? buf : "",