linux-kernel - [PATCH 3/3] kernel/irq/manage.c: disable

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Date:   Fri, 16 Dec 2022 16:04:41 +0100
From:   Manfred Spraul <manfred@...orfullife.com>
To:     LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     1vier1@....de, Manfred Spraul <manfred@...orfullife.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
Subject: [PATCH 3/3] kernel/irq/manage.c: disable_irq() might sleep.

With the introduction of threaded interrupt handlers, it is virtually
never safe to call disable_irq() from non-premptible context.

Thus: Update the documentation, add a might_sleep() to catch any
offenders.

Fixes: 3aa551c9b4c4 ("genirq: add threaded interrupt handler support")

Signed-off-by: Manfred Spraul <manfred@...orfullife.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
---
 kernel/irq/manage.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5b7cf28df290..8ce75495e04f 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -723,10 +723,13 @@ EXPORT_SYMBOL(disable_irq_nosync);
  *	to complete before returning. If you use this function while
  *	holding a resource the IRQ handler may need you will deadlock.
  *
- *	This function may be called - with care - from IRQ context.
+ *	Can only be called from preemptible code as it might sleep when
+ *	an interrupt thread is associated to @irq.
+ *
  */
 void disable_irq(unsigned int irq)
 {
+	might_sleep();
 	if (!__disable_irq_nosync(irq))
 		synchronize_irq(irq);
 }
-- 
2.38.1