linux-kernel - [PATCH MANUALSEL 5.15 2/5] genirq/irq_sim: Make the irq

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Message-Id: <20220605135412.61517-2-sashal@kernel.org>
Date:   Sun,  5 Jun 2022 09:54:06 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH MANUALSEL 5.15 2/5] genirq/irq_sim: Make the irq_work always run in hard irq context

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

[ Upstream commit 21673fcb2532dcd189905ff5a5389eb7dcd0e57a ]

The IRQ simulator uses irq_work to trigger an interrupt. Without the
IRQ_WORK_HARD_IRQ flag the irq_work will be performed in thread context
on PREEMPT_RT. This causes locking errors later in handle_simple_irq()
which expects to be invoked with disabled interrupts.

Triggering individual interrupts in hardirq context should not lead to
unexpected high latencies since this is also what the hardware
controller does. Also it is used as a simulator so...

Use IRQ_WORK_INIT_HARD() to carry out the irq_work in hardirq context on
PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/YnuZBoEVMGwKkLm+@linutronix.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/irq/irq_sim.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index 0cd02efa3a74..dd76323ea3fd 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -181,7 +181,7 @@ struct irq_domain *irq_domain_create_sim(struct fwnode_handle *fwnode,
 		goto err_free_bitmap;
 
 	work_ctx->irq_count = num_irqs;
-	init_irq_work(&work_ctx->work, irq_sim_handle_irq);
+	work_ctx->work = IRQ_WORK_INIT_HARD(irq_sim_handle_irq);
 
 	return work_ctx->domain;
 
-- 
2.35.1