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Subject[RFC][PATCH 1/4] acpi: Use CPUIDLE_FLAG_TIMER_STOP
Make acpi_processor_idle use the common broadcast code, there's no
reason not to. This also removes some RCU usage after
rcu_idle_enter().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
drivers/acpi/processor_idle.c | 49 +++++++++++++-----------------------------
1 file changed, 16 insertions(+), 33 deletions(-)

--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -161,18 +161,10 @@ static void lapic_timer_propagate_broadc
}

/* Power(C) State timer broadcast control */
-static void lapic_timer_state_broadcast(struct acpi_processor *pr,
- struct acpi_processor_cx *cx,
- int broadcast)
-{
- int state = cx - pr->power.states;
-
- if (state >= pr->power.timer_broadcast_on_state) {
- if (broadcast)
- tick_broadcast_enter();
- else
- tick_broadcast_exit();
- }
+static bool lapic_timer_needs_broadcast(struct acpi_processor *pr,
+ struct acpi_processor_cx *cx)
+{
+ return cx - pr->power.states >= pr->power.timer_broadcast_on_state;
}

#else
@@ -180,9 +172,9 @@ static void lapic_timer_state_broadcast(
static void lapic_timer_check_state(int state, struct acpi_processor *pr,
struct acpi_processor_cx *cstate) { }
static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }
-static void lapic_timer_state_broadcast(struct acpi_processor *pr,
- struct acpi_processor_cx *cx,
- int broadcast)
+
+static bool lapic_timer_needs_broadcast(struct acpi_processor *pr,
+ struct acpi_processor_cx *cx)
{
}

@@ -568,21 +560,13 @@ static DEFINE_RAW_SPINLOCK(c3_lock);
* acpi_idle_enter_bm - enters C3 with proper BM handling
* @pr: Target processor
* @cx: Target state context
- * @timer_bc: Whether or not to change timer mode to broadcast
*/
static void acpi_idle_enter_bm(struct acpi_processor *pr,
- struct acpi_processor_cx *cx, bool timer_bc)
+ struct acpi_processor_cx *cx)
{
acpi_unlazy_tlb(smp_processor_id());

/*
- * Must be done before busmaster disable as we might need to
- * access HPET !
- */
- if (timer_bc)
- lapic_timer_state_broadcast(pr, cx, 1);
-
- /*
* disable bus master
* bm_check implies we need ARB_DIS
* bm_control implies whether we can do ARB_DIS
@@ -609,9 +593,6 @@ static void acpi_idle_enter_bm(struct ac
c3_cpu_count--;
raw_spin_unlock(&c3_lock);
}
-
- if (timer_bc)
- lapic_timer_state_broadcast(pr, cx, 0);
}

static int acpi_idle_enter(struct cpuidle_device *dev,
@@ -630,7 +611,7 @@ static int acpi_idle_enter(struct cpuidl
cx = per_cpu(acpi_cstate[index], dev->cpu);
} else if (cx->type == ACPI_STATE_C3 && pr->flags.bm_check) {
if (cx->bm_sts_skip || !acpi_idle_bm_check()) {
- acpi_idle_enter_bm(pr, cx, true);
+ acpi_idle_enter_bm(pr, cx);
return index;
} else if (drv->safe_state_index >= 0) {
index = drv->safe_state_index;
@@ -642,15 +623,11 @@ static int acpi_idle_enter(struct cpuidl
}
}

- lapic_timer_state_broadcast(pr, cx, 1);
-
if (cx->type == ACPI_STATE_C3)
ACPI_FLUSH_CPU_CACHE();

acpi_idle_do_entry(cx);

- lapic_timer_state_broadcast(pr, cx, 0);
-
return index;
}

@@ -666,7 +643,7 @@ static int acpi_idle_enter_s2idle(struct
return 0;

if (pr->flags.bm_check) {
- acpi_idle_enter_bm(pr, cx, false);
+ acpi_idle_enter_bm(pr, cx);
return 0;
} else {
ACPI_FLUSH_CPU_CACHE();
@@ -682,6 +659,7 @@ static int acpi_processor_setup_cpuidle_
{
int i, count = ACPI_IDLE_STATE_START;
struct acpi_processor_cx *cx;
+ struct cpuidle_state *state;

if (max_cstate == 0)
max_cstate = 1;
@@ -694,6 +672,11 @@ static int acpi_processor_setup_cpuidle_

per_cpu(acpi_cstate[count], dev->cpu) = cx;

+ if (lapic_timer_needs_broadcast(pr, cx)) {
+ state = &acpi_idle_driver.states[count];
+ state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+ }
+
count++;
if (count == CPUIDLE_STATE_MAX)
break;

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