linux-kernel - [PATCH 6/9] pm/irq: make for_each_irq_desc() safe of irq

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Date:   Wed, 20 Apr 2022 22:05:18 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Pingfan Liu <kernelfans@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: [PATCH 6/9] pm/irq: make for_each_irq_desc() safe of irq_desc release

The invloved context is no a RCU read section. Furthermore there may be
more than one task at this point. Hence it demands a measure to prevent
irq_desc from freeing. Use irq_lock_sparse to serve the protection
purpose.

Signed-off-by: Pingfan Liu <kernelfans@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>
To: linux-kernel@...r.kernel.org
---
 kernel/irq/pm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
index ca71123a6130..4b67a4c7de3c 100644
--- a/kernel/irq/pm.c
+++ b/kernel/irq/pm.c
@@ -133,6 +133,7 @@ void suspend_device_irqs(void)
 	struct irq_desc *desc;
 	int irq;
 
+	irq_lock_sparse();
 	for_each_irq_desc(irq, desc) {
 		unsigned long flags;
 		bool sync;
@@ -146,6 +147,7 @@ void suspend_device_irqs(void)
 		if (sync)
 			synchronize_irq(irq);
 	}
+	irq_unlock_sparse();
 }
 EXPORT_SYMBOL_GPL(suspend_device_irqs);
 
@@ -186,6 +188,7 @@ static void resume_irqs(bool want_early)
 	struct irq_desc *desc;
 	int irq;
 
+	/* The early resume stage is free of irq_desc release */
 	for_each_irq_desc(irq, desc) {
 		unsigned long flags;
 		bool is_early = desc->action &&
-- 
2.31.1