rcu: Remove rcu_dynticks * parameters when they are always this_cpu_ptr(&rcu_dynticks)

* rcu: Remove rcu_dynticks * parameters when they are always this_cpu_ptr(&rcu_dynticks)
@ 2014-09-02 20:13 Christoph Lameter
  2014-09-02 20:58 ` Paul E. McKenney
  0 siblings, 1 reply; 2+ messages in thread
From: Christoph Lameter @ 2014-09-02 20:13 UTC (permalink / raw)
  To: Paul E. McKenney; +Cc: Frederic Weisbecker, linux-kernel

For some functions in kernel/rcu/tree* the rdtp parameter is always this_cpu_ptr(rdtp).
Remove the parameter if constant and calculate the pointer in function.

This will have the advantage that it is obvious that the address are all per cpu
offsets and thus it will enable the use of this_cpu_ops in the future.

Signed-off-by: Christoph Lameter <cl@linux.com>

Index: linux/kernel/rcu/tree.c
===================================================================

--- linux.orig/kernel/rcu/tree.c
+++ linux/kernel/rcu/tree.c
@@ -499,11 +499,11 @@ cpu_needs_another_gp(struct rcu_state *r
  * we really have entered idle, and must do the appropriate accounting.
  * The caller must have disabled interrupts.
  */
-static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval,
-				bool user)
+static void rcu_eqs_enter_common(long long oldval, bool user)
 {
 	struct rcu_state *rsp;
 	struct rcu_data *rdp;
+	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);

 	trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
 	if (!user && !is_idle_task(current)) {
@@ -553,7 +553,7 @@ static void rcu_eqs_enter(bool user)
 	WARN_ON_ONCE((oldval & DYNTICK_TASK_NEST_MASK) == 0);
 	if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
 		rdtp->dynticks_nesting = 0;
-		rcu_eqs_enter_common(rdtp, oldval, user);
+		rcu_eqs_enter_common(oldval, user);
 	} else {
 		rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
 	}
@@ -577,7 +577,7 @@ void rcu_idle_enter(void)

 	local_irq_save(flags);
 	rcu_eqs_enter(false);
-	rcu_sysidle_enter(this_cpu_ptr(&rcu_dynticks), 0);
+	rcu_sysidle_enter(0);
 	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
@@ -627,8 +627,8 @@ void rcu_irq_exit(void)
 	if (rdtp->dynticks_nesting)
 		trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting);
 	else
-		rcu_eqs_enter_common(rdtp, oldval, true);
-	rcu_sysidle_enter(rdtp, 1);
+		rcu_eqs_enter_common(oldval, true);
+	rcu_sysidle_enter(1);
 	local_irq_restore(flags);
 }

@@ -639,9 +639,11 @@ void rcu_irq_exit(void)
  * we really have exited idle, and must do the appropriate accounting.
  * The caller must have disabled interrupts.
  */
-static void rcu_eqs_exit_common(struct rcu_dynticks *rdtp, long long oldval,
+static void rcu_eqs_exit_common(long long oldval,
 			       int user)
 {
+	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+
 	smp_mb__before_atomic();  /* Force ordering w/previous sojourn. */
 	atomic_inc(&rdtp->dynticks);
 	/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
@@ -678,7 +680,7 @@ static void rcu_eqs_exit(bool user)
 		rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
 	} else {
 		rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
-		rcu_eqs_exit_common(rdtp, oldval, user);
+		rcu_eqs_exit_common(oldval, user);
 	}
 }

@@ -699,7 +701,7 @@ void rcu_idle_exit(void)

 	local_irq_save(flags);
 	rcu_eqs_exit(false);
-	rcu_sysidle_exit(this_cpu_ptr(&rcu_dynticks), 0);
+	rcu_sysidle_exit(0);
 	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_exit);
@@ -750,8 +752,8 @@ void rcu_irq_enter(void)
 	if (oldval)
 		trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting);
 	else
-		rcu_eqs_exit_common(rdtp, oldval, true);
-	rcu_sysidle_exit(rdtp, 1);
+		rcu_eqs_exit_common(oldval, true);
+	rcu_sysidle_exit(1);
 	local_irq_restore(flags);
 }

Index: linux/kernel/rcu/tree.h
===================================================================
--- linux.orig/kernel/rcu/tree.h
+++ linux/kernel/rcu/tree.h
@@ -595,8 +595,8 @@ static void rcu_boot_init_nocb_percpu_da
 static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp);
 static void __maybe_unused rcu_kick_nohz_cpu(int cpu);
 static bool init_nocb_callback_list(struct rcu_data *rdp);
-static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq);
-static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq);
+static void rcu_sysidle_enter(int irq);
+static void rcu_sysidle_exit(int irq);
 static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
 				  unsigned long *maxj);
 static bool is_sysidle_rcu_state(struct rcu_state *rsp);
Index: linux/kernel/rcu/tree_plugin.h
===================================================================
--- linux.orig/kernel/rcu/tree_plugin.h
+++ linux/kernel/rcu/tree_plugin.h
@@ -2618,9 +2618,10 @@ static int full_sysidle_state;		/* Curre
  * to detect full-system idle states, not RCU quiescent states and grace
  * periods.  The caller must have disabled interrupts.
  */
-static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_enter(int irq)
 {
 	unsigned long j;
+	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);

 	/* Adjust nesting, check for fully idle. */
 	if (irq) {
@@ -2685,8 +2686,9 @@ void rcu_sysidle_force_exit(void)
  * usermode execution does -not- count as idle here!  The caller must
  * have disabled interrupts.
  */
-static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_exit(int irq)
 {
+	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 	/* Adjust nesting, check for already non-idle. */
 	if (irq) {
 		rdtp->dynticks_idle_nesting++;
@@ -2968,11 +2970,11 @@ static void rcu_sysidle_init_percpu_data

 #else /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */

-static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_enter(int irq)
 {
 }

-static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq)
+static void rcu_sysidle_exit(int irq)
 {
 }


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