From: Waiman Long <longman@redhat.com>
Date: Sat, 23 Jul 2022 19:59:32 +0000 (-0400)
Subject: intel_idle: Fix false positive RCU splats due to incorrect hardirqs state
X-Git-Tag: howlett/maple/20220816~303^2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d295ad34f236;p=users%2Fjedix%2Flinux-maple.git

intel_idle: Fix false positive RCU splats due to incorrect hardirqs state

Commit 32d4fd5751ea ("cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE")
uses raw_local_irq_enable/local_irq_disable() around call to
__intel_idle() in intel_idle_irq().

With interrupt enabled, timer tick interrupt can happen and a
subsequently call to __do_softirq() may change the lockdep hardirqs state
of a debug kernel back to 'on'. This will result in a mismatch between
the cpu hardirqs state (off) and the lockdep hardirqs state (on) causing
a number of false positive "WARNING: suspicious RCU usage" splats.

Fix that by using local_irq_disable() to disable interrupt in
intel_idle_irq().

Fixes: 32d4fd5751ea ("cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE")
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: 5.16+ <stable@vger.kernel.org> # 5.16+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index f5c6802aa6c3..907700d1e78e 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -162,7 +162,13 @@ static __cpuidle int intel_idle_irq(struct cpuidle_device *dev,
 
 	raw_local_irq_enable();
 	ret = __intel_idle(dev, drv, index);
-	raw_local_irq_disable();
+
+	/*
+	 * The lockdep hardirqs state may be changed to 'on' with timer
+	 * tick interrupt followed by __do_softirq(). Use local_irq_disable()
+	 * to keep the hardirqs state correct.
+	 */
+	local_irq_disable();
 
 	return ret;
 }