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Subject[PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE
Commit c227233ad64c ("intel_idle: enable interrupts before C1 on
Xeons") wrecked intel_idle in two ways:

- must not have tracing in idle functions
- must return with IRQs disabled

Additionally, it added a branch for no good reason.

Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
drivers/idle/intel_idle.c | 48 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 37 insertions(+), 11 deletions(-)

--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -129,21 +137,37 @@ static unsigned int mwait_substates __in
*
* Must be called under local_irq_disable().
*/
+
-static __cpuidle int intel_idle(struct cpuidle_device *dev,
- struct cpuidle_driver *drv, int index)
+static __always_inline int __intel_idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
{
struct cpuidle_state *state = &drv->states[index];
unsigned long eax = flg2MWAIT(state->flags);
unsigned long ecx = 1; /* break on interrupt flag */

- if (state->flags & CPUIDLE_FLAG_IRQ_ENABLE)
- local_irq_enable();
-
mwait_idle_with_hints(eax, ecx);

return index;
}

+static __cpuidle int intel_idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ return __intel_idle(dev, drv, index);
+}
+
+static __cpuidle int intel_idle_irq(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ int ret;
+
+ raw_local_irq_enable();
+ ret = __intel_idle(dev, drv, index);
+ raw_local_irq_disable();
+
+ return ret;
+}
+
/**
* intel_idle_s2idle - Ask the processor to enter the given idle state.
* @dev: cpuidle device of the target CPU.
@@ -1801,6 +1824,9 @@ static void __init intel_idle_init_cstat
/* Structure copy. */
drv->states[drv->state_count] = cpuidle_state_table[cstate];

+ if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_IRQ_ENABLE)
+ drv->states[drv->state_count].enter = intel_idle_irq;
+
if ((disabled_states_mask & BIT(drv->state_count)) ||
((icpu->use_acpi || force_use_acpi) &&
intel_idle_off_by_default(mwait_hint) &&

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