From a2966bf977ec9657c63a9a1015e2ef9426081c75 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 21 Aug 2013 17:48:46 +0200
Subject: [PATCH 191/518] genirq: Do not invoke the affinity callback via a
 workqueue on RT

Joe Korty reported, that __irq_set_affinity_locked() schedules a
workqueue while holding a rawlock which results in a might_sleep()
warning.
This patch uses swork_queue() instead.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 include/linux/interrupt.h |  6 ++++++
 kernel/irq/manage.c       | 44 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 2395ebb443b94..172376b9a0499 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -15,6 +15,7 @@
 #include <linux/hrtimer.h>
 #include <linux/kref.h>
 #include <linux/workqueue.h>
+#include <linux/swork.h>
 
 #include <linux/atomic.h>
 #include <asm/ptrace.h>
@@ -227,6 +228,7 @@ extern void resume_device_irqs(void);
  * struct irq_affinity_notify - context for notification of IRQ affinity changes
  * @irq:		Interrupt to which notification applies
  * @kref:		Reference count, for internal use
+ * @swork:		Swork item, for internal use
  * @work:		Work item, for internal use
  * @notify:		Function to be called on change.  This will be
  *			called in process context.
@@ -238,7 +240,11 @@ extern void resume_device_irqs(void);
 struct irq_affinity_notify {
 	unsigned int irq;
 	struct kref kref;
+#ifdef CONFIG_PREEMPT_RT_BASE
+	struct swork_event swork;
+#else
 	struct work_struct work;
+#endif
 	void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
 	void (*release)(struct kref *ref);
 };
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index bf525d789ba13..1cf2a2e81282a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -263,7 +263,11 @@ int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
 
 	if (desc->affinity_notify) {
 		kref_get(&desc->affinity_notify->kref);
+#ifdef CONFIG_PREEMPT_RT_BASE
+		if (!swork_queue(&desc->affinity_notify->swork)) {
+#else
 		if (!schedule_work(&desc->affinity_notify->work)) {
+#endif
 			/* Work was already scheduled, drop our extra ref */
 			kref_put(&desc->affinity_notify->kref,
 				 desc->affinity_notify->release);
@@ -305,10 +309,8 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 }
 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 
-static void irq_affinity_notify(struct work_struct *work)
+static void _irq_affinity_notify(struct irq_affinity_notify *notify)
 {
-	struct irq_affinity_notify *notify =
-		container_of(work, struct irq_affinity_notify, work);
 	struct irq_desc *desc = irq_to_desc(notify->irq);
 	cpumask_var_t cpumask;
 	unsigned long flags;
@@ -330,6 +332,35 @@ static void irq_affinity_notify(struct work_struct *work)
 	kref_put(&notify->kref, notify->release);
 }
 
+#ifdef CONFIG_PREEMPT_RT_BASE
+static void init_helper_thread(void)
+{
+	static int init_sworker_once;
+
+	if (init_sworker_once)
+		return;
+	if (WARN_ON(swork_get()))
+		return;
+	init_sworker_once = 1;
+}
+
+static void irq_affinity_notify(struct swork_event *swork)
+{
+	struct irq_affinity_notify *notify =
+		container_of(swork, struct irq_affinity_notify, swork);
+	_irq_affinity_notify(notify);
+}
+
+#else
+
+static void irq_affinity_notify(struct work_struct *work)
+{
+	struct irq_affinity_notify *notify =
+		container_of(work, struct irq_affinity_notify, work);
+	_irq_affinity_notify(notify);
+}
+#endif
+
 /**
  *	irq_set_affinity_notifier - control notification of IRQ affinity changes
  *	@irq:		Interrupt for which to enable/disable notification
@@ -358,7 +389,12 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 	if (notify) {
 		notify->irq = irq;
 		kref_init(&notify->kref);
+#ifdef CONFIG_PREEMPT_RT_BASE
+		INIT_SWORK(&notify->swork, irq_affinity_notify);
+		init_helper_thread();
+#else
 		INIT_WORK(&notify->work, irq_affinity_notify);
+#endif
 	}
 
 	raw_spin_lock_irqsave(&desc->lock, flags);
@@ -367,10 +403,12 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 
 	if (old_notify) {
+#ifndef CONFIG_PREEMPT_RT_BASE
 		if (cancel_work_sync(&old_notify->work)) {
 			/* Pending work had a ref, put that one too */
 			kref_put(&old_notify->kref, old_notify->release);
 		}
+#endif
 		kref_put(&old_notify->kref, old_notify->release);
 	}
 
-- 
2.41.0

