ACPI / cpuidle: Common callback routine for entering states

Introduce a common ->enter callback routine for the ACPI cpuidle
driver, acpi_idle_enter(), which helps to reduce code complexity,
size and duplication and prevents theoretically possible failues that
an incorrect routine may be run to enter the given idle state due to
a firmware bug (eg. when _CST returns a different set of states for
each processor).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 45 insertions, 73 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 58113a6fa1d3..c256bd7fbd78 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -737,74 +737,17 @@ static bool acpi_idle_fallback_to_c1(struct acpi_processor *pr)
                 !pr->flags.has_cst;
 }
 
-/**
- * acpi_idle_enter_simple - enters a CPU idle state without BM handling
- * @dev: the target CPU
- * @drv: cpuidle driver with cpuidle state information
- * @index: the index of suggested state
- */
-static int acpi_idle_enter_simple(struct cpuidle_device *dev,
-                struct cpuidle_driver *drv, int index)
-{
-        struct acpi_processor *pr;
-        struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
-
-        pr = __this_cpu_read(processors);
-
-        if (unlikely(!pr))
-                return -EINVAL;
-
-        if (cx->type != ACPI_STATE_C1 && acpi_idle_fallback_to_c1(pr)) {
-                index = CPUIDLE_DRIVER_STATE_START;
-                cx = per_cpu(acpi_cstate[index], dev->cpu);
-        }
-
-        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;
-}
-
 static int c3_cpu_count;
 static DEFINE_RAW_SPINLOCK(c3_lock);
 
 /**
  * acpi_idle_enter_bm - enters C3 with proper BM handling
- * @dev: the target CPU
- * @drv: cpuidle driver containing state data
- * @index: the index of suggested state
- *
- * If BM is detected, the deepest non-C3 idle state is entered instead.
+ * @pr: Target processor
+ * @cx: Target state context
  */
-static int acpi_idle_enter_bm(struct cpuidle_device *dev,
-                struct cpuidle_driver *drv, int index)
+static void acpi_idle_enter_bm(struct acpi_processor *pr,
+                               struct acpi_processor_cx *cx)
 {
-        struct acpi_processor *pr;
-        struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
-
-        pr = __this_cpu_read(processors);
-
-        if (unlikely(!pr))
-                return -EINVAL;
-
-        if (acpi_idle_fallback_to_c1(pr))
-                return acpi_idle_enter_simple(dev, drv, CPUIDLE_DRIVER_STATE_START);
-
-        if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
-                if (drv->safe_state_index >= 0) {
-                        return drv->states[drv->safe_state_index].enter(dev,
-                                                drv, drv->safe_state_index);
-                } else {
-                        acpi_safe_halt();
-                        return -EBUSY;
-                }
-        }
-
         acpi_unlazy_tlb(smp_processor_id());
 
         /*
@@ -842,6 +785,45 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
         }
 
         lapic_timer_state_broadcast(pr, cx, 0);
+}
+
+static int acpi_idle_enter(struct cpuidle_device *dev,
+                           struct cpuidle_driver *drv, int index)
+{
+        struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
+        struct acpi_processor *pr;
+
+        pr = __this_cpu_read(processors);
+        if (unlikely(!pr))
+                return -EINVAL;
+
+        if (cx->type != ACPI_STATE_C1) {
+                if (acpi_idle_fallback_to_c1(pr)) {
+                        index = CPUIDLE_DRIVER_STATE_START;
+                        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);
+                                return index;
+                        } else if (drv->safe_state_index >= 0) {
+                                index = drv->safe_state_index;
+                                cx = per_cpu(acpi_cstate[index], dev->cpu);
+                        } else {
+                                acpi_safe_halt();
+                                return -EBUSY;
+                        }
+                }
+        }
+
+        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;
 }
 
@@ -936,22 +918,12 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
                 strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
                 state->exit_latency = cx->latency;
                 state->target_residency = cx->latency * latency_factor;
+                state->enter = acpi_idle_enter;
 
                 state->flags = 0;
-                switch (cx->type) {
-
-                case ACPI_STATE_C1:
-                case ACPI_STATE_C2:
-                        state->enter = acpi_idle_enter_simple;
+                if (cx->type == ACPI_STATE_C1 || cx->type == ACPI_STATE_C2) {
                         state->enter_dead = acpi_idle_play_dead;
                         drv->safe_state_index = count;
-                        break;
-
-                case ACPI_STATE_C3:
-                        state->enter = pr->flags.bm_check ?
-                                        acpi_idle_enter_bm :
-                                        acpi_idle_enter_simple;
-                        break;
                 }
 
                 count++;