[PATCH 3/7] intel_idle: Add a sanity check in the new state_update_enter_method function

[arjan@linux.intel.com]

From: Arjan van de Ven <arjan.van.de.ven@intel.com>

The state_update_enter_method function updates a state's enter function pointer,
but does so assuming that the current function is "intel_idle" or "intel_idle_irq".

In the code currently that's basically the case, but soon this will change.
Add a sanity check early in the function to make the assumption explicit,
and return early if the precondition is not met.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
 drivers/idle/intel_idle.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 256c2d42e350..8415965372c7 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1841,6 +1841,14 @@ static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
 
 static void state_update_enter_method(struct cpuidle_state *state, int cstate)
 {
+	/*
+	 * The updates below are only valid if state->enter is actually the
+	 * 'intel_idle' or 'intel_idle_irq' functions; for all other cases
+	 * we just bow out early.
+	 */
+	if (state->enter != intel_idle && state->enter != intel_idle_irq )
+		return;
+
 	if (state->flags & CPUIDLE_FLAG_INIT_XSTATE) {
 		/*
 		 * Combining with XSTATE with IBRS or IRQ_ENABLE flags
-- 
2.40.1