linux-kernel - [PATCH RT 02/16] genirq: Do not invoke the affinity callback via a workqueue on RT

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Date:   Fri, 19 Jul 2019 17:49:33 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Julia Cartwright <julia@...com>,
        Daniel Wagner <wagi@...om.org>, tom.zanussi@...ux.intel.com
Subject: [PATCH RT 02/16] genirq: Do not invoke the affinity callback via a workqueue on RT

4.19.59-rt24-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

[ Upstream commit 2122adbe011cdc0eb62ad62494e181005b23c76a ]

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@...utronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 include/linux/interrupt.h |  5 ++---
 kernel/irq/manage.c       | 19 ++++---------------
 2 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 72333899f043..a9321f6429f2 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -13,7 +13,7 @@
 #include <linux/hrtimer.h>
 #include <linux/kref.h>
 #include <linux/workqueue.h>
-#include <linux/swork.h>
+#include <linux/kthread.h>
 
 #include <linux/atomic.h>
 #include <asm/ptrace.h>
@@ -228,7 +228,6 @@ 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.
@@ -241,7 +240,7 @@ struct irq_affinity_notify {
 	unsigned int irq;
 	struct kref kref;
 #ifdef CONFIG_PREEMPT_RT_BASE
-	struct swork_event swork;
+	struct kthread_work work;
 #else
 	struct work_struct work;
 #endif
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 7f4041357d2f..381305c48a0a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -261,7 +261,7 @@ int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
 		kref_get(&desc->affinity_notify->kref);
 
 #ifdef CONFIG_PREEMPT_RT_BASE
-		swork_queue(&desc->affinity_notify->swork);
+		kthread_schedule_work(&desc->affinity_notify->work);
 #else
 		schedule_work(&desc->affinity_notify->work);
 #endif
@@ -326,21 +326,11 @@ static void _irq_affinity_notify(struct irq_affinity_notify *notify)
 }
 
 #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)
+static void irq_affinity_notify(struct kthread_work *work)
 {
 	struct irq_affinity_notify *notify =
-		container_of(swork, struct irq_affinity_notify, swork);
+		container_of(work, struct irq_affinity_notify, work);
 	_irq_affinity_notify(notify);
 }
 
@@ -383,8 +373,7 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 		notify->irq = irq;
 		kref_init(&notify->kref);
 #ifdef CONFIG_PREEMPT_RT_BASE
-		INIT_SWORK(&notify->swork, irq_affinity_notify);
-		init_helper_thread();
+		kthread_init_work(&notify->work, irq_affinity_notify);
 #else
 		INIT_WORK(&notify->work, irq_affinity_notify);
 #endif
-- 
2.20.1