linux-kernel - [PATCH 02/15] ARM: pass IRQ domain to the core IRQ handler

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Date:	Tue,  8 Jul 2014 14:10:25 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Alexander Shiyan <shc_work@...l.ru>,
	Barry Song <baohua@...nel.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Kevin Hilman <khilman@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Larry Bassel <larry.bassel@...aro.org>,
	Mark Rutland <mark.rutland@....com>,
	Sudeep Holla <sudeep.holla@....com>
Subject: [PATCH 02/15] ARM: pass IRQ domain to the core IRQ handler

Calling irq_find_mapping from outside a irq_{enter,exit} section is
unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled:
If coming from the idle state, the rcu_read_lock call in irq_find_mapping
will generate an an unpleasant warning.

A solution is to add a new handle_domain_irq entry point into
the arm code that the interrupt controller code can call.
This new function takes an irq_domain, and calls into irq_find_domain
inside the irq_{enter,exit} block.

Interrupt controllers can then be updated to use the new mechanism.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 arch/arm/include/asm/irq.h |  2 ++
 arch/arm/kernel/irq.c      | 23 +++++++++++++++++++----
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index 53c15de..8578811 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -24,10 +24,12 @@
 #ifndef __ASSEMBLY__
 struct irqaction;
 struct pt_regs;
+struct irq_domain;
 extern void migrate_irqs(void);
 
 extern void asm_do_IRQ(unsigned int, struct pt_regs *);
 void handle_IRQ(unsigned int, struct pt_regs *);
+void handle_domain_irq(struct irq_domain *, unsigned int, struct pt_regs *);
 void init_IRQ(void);
 
 #ifdef CONFIG_MULTI_IRQ_HANDLER
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 2c42576..d6af69f5 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -62,20 +62,30 @@ int arch_show_interrupts(struct seq_file *p, int prec)
  * not come via this function.  Instead, they should provide their
  * own 'handler'.  Used by platform code implementing C-based 1st
  * level decoding.
+ *
+ * handle_domain_irq does the same thing, but also converts the HW
+ * interrupt number into a logical one using the provided domain. A
+ * NULL domain indicates that this conversion has already been done.
  */
-void handle_IRQ(unsigned int irq, struct pt_regs *regs)
+void handle_domain_irq(struct irq_domain *domain,
+		       unsigned int hwirq, struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
+	unsigned int irq;
 
 	irq_enter();
 
+	if (domain)
+		irq = irq_find_mapping(domain, hwirq);
+	else
+		irq = hwirq;
+
 	/*
 	 * Some hardware gives randomly wrong interrupts.  Rather
 	 * than crashing, do something sensible.
 	 */
-	if (unlikely(irq >= nr_irqs)) {
-		if (printk_ratelimit())
-			printk(KERN_WARNING "Bad IRQ%u\n", irq);
+	if (unlikely(!irq || irq >= nr_irqs)) {
+		pr_warn_ratelimited("Bad IRQ%u (%u)\n", irq, hwirq);
 		ack_bad_irq(irq);
 	} else {
 		generic_handle_irq(irq);
@@ -85,6 +95,11 @@ void handle_IRQ(unsigned int irq, struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+void handle_IRQ(unsigned int irq, struct pt_regs *regs)
+{
+	handle_domain_irq(NULL, irq, regs);
+}
+
 /*
  * asm_do_IRQ is the interface to be used from assembly code.
  */
-- 
2.0.0

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