linux-kernel - [PATCH RFC 02/12] entry/idle: Add a common function for activites during idle entry/exit

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Date:   Fri, 14 Aug 2020 23:18:58 -0400
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Kees Cook <keescook@...omium.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Paul Turner <pjt@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tim Chen <tim.c.chen@...el.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        fweisbec@...il.com, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH RFC 02/12] entry/idle: Add a common function for activites during idle entry/exit

Currently only RCU hooks for idle entry/exit are called. In later
patches, kernel-entry protection functionality will be added.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 include/linux/entry-common.h | 16 ++++++++++++++++
 kernel/sched/idle.c          | 17 +++++++++--------
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index efebbffcd5cc..2ea0e09b00d5 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -369,4 +369,20 @@ void irqentry_exit_cond_resched(void);
  */
 void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
 
+/**
+ * generic_idle_enter - Called during entry into idle for housekeeping.
+ */
+static inline void generic_idle_enter(void)
+{
+	rcu_idle_enter();
+}
+
+/**
+ * generic_idle_enter - Called when exiting idle for housekeeping.
+ */
+static inline void generic_idle_exit(void)
+{
+	rcu_idle_exit();
+}
+
 #endif
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 3b03bedee280..5db5a946aa3b 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -8,6 +8,7 @@
  */
 #include "sched.h"
 
+#include <linux/entry-common.h>
 #include <trace/events/power.h>
 
 /* Linker adds these: start and end of __cpuidle functions */
@@ -54,7 +55,7 @@ __setup("hlt", cpu_idle_nopoll_setup);
 
 static noinline int __cpuidle cpu_idle_poll(void)
 {
-	rcu_idle_enter();
+	generic_idle_enter();
 	trace_cpu_idle_rcuidle(0, smp_processor_id());
 	local_irq_enable();
 	stop_critical_timings();
@@ -64,7 +65,7 @@ static noinline int __cpuidle cpu_idle_poll(void)
 		cpu_relax();
 	start_critical_timings();
 	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
-	rcu_idle_exit();
+	generic_idle_exit();
 
 	return 1;
 }
@@ -158,7 +159,7 @@ static void cpuidle_idle_call(void)
 
 	if (cpuidle_not_available(drv, dev)) {
 		tick_nohz_idle_stop_tick();
-		rcu_idle_enter();
+		generic_idle_enter();
 
 		default_idle_call();
 		goto exit_idle;
@@ -178,13 +179,13 @@ static void cpuidle_idle_call(void)
 		u64 max_latency_ns;
 
 		if (idle_should_enter_s2idle()) {
-			rcu_idle_enter();
+			generic_idle_enter();
 
 			entered_state = call_cpuidle_s2idle(drv, dev);
 			if (entered_state > 0)
 				goto exit_idle;
 
-			rcu_idle_exit();
+			generic_idle_exit();
 
 			max_latency_ns = U64_MAX;
 		} else {
@@ -192,7 +193,7 @@ static void cpuidle_idle_call(void)
 		}
 
 		tick_nohz_idle_stop_tick();
-		rcu_idle_enter();
+		generic_idle_enter();
 
 		next_state = cpuidle_find_deepest_state(drv, dev, max_latency_ns);
 		call_cpuidle(drv, dev, next_state);
@@ -209,7 +210,7 @@ static void cpuidle_idle_call(void)
 		else
 			tick_nohz_idle_retain_tick();
 
-		rcu_idle_enter();
+		generic_idle_enter();
 
 		entered_state = call_cpuidle(drv, dev, next_state);
 		/*
@@ -227,7 +228,7 @@ static void cpuidle_idle_call(void)
 	if (WARN_ON_ONCE(irqs_disabled()))
 		local_irq_enable();
 
-	rcu_idle_exit();
+	generic_idle_exit();
 }
 
 /*
-- 
2.28.0.220.ged08abb693-goog