linux-kernel - [PATCH v2 1/6] genirq: Add __irq_modify_status() helper to clear/set special flags

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Date:   Tue, 24 Nov 2020 14:14:44 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     LAK <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Cc:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Valentin Schneider <Valentin.Schneider@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@....linux.org.uk>,
        Android Kernel Team <kernel-team@...roid.com>
Subject: [PATCH v2 1/6] genirq: Add __irq_modify_status() helper to clear/set special flags

Some arch-specific flags need to be set/cleared, but not exposed to
random device drivers. Introduce a new helper (__irq_modify_status())
that takes an arbitrary mask, and rewrite irq_modify_status() to use
this new helper.

No functionnal change.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 include/linux/irq.h   |  3 +++
 kernel/irq/chip.c     | 12 ++++++++++--
 kernel/irq/settings.h | 10 ++++++++--
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c54365309e97..c55f218d5b61 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -751,6 +751,9 @@ void
 irq_set_chained_handler_and_data(unsigned int irq, irq_flow_handler_t handle,
 				 void *data);
 
+void __irq_modify_status(unsigned int irq, unsigned long clr,
+			 unsigned long set, unsigned long mask);
+
 void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set);
 
 static inline void irq_set_status_flags(unsigned int irq, unsigned long set)
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b9b9618e1aca..85176712a484 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1107,7 +1107,8 @@ irq_set_chip_and_handler_name(unsigned int irq, struct irq_chip *chip,
 }
 EXPORT_SYMBOL_GPL(irq_set_chip_and_handler_name);
 
-void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
+void __irq_modify_status(unsigned int irq, unsigned long clr,
+			 unsigned long set, unsigned long mask)
 {
 	unsigned long flags, trigger, tmp;
 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
@@ -1121,7 +1122,9 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 	 */
 	WARN_ON_ONCE(!desc->depth && (set & _IRQ_NOAUTOEN));
 
-	irq_settings_clr_and_set(desc, clr, set);
+	/* Warn when trying to clear or set a bit disallowed by the mask */
+	WARN_ON((clr | set) & ~mask);
+	__irq_settings_clr_and_set(desc, clr, set, mask);
 
 	trigger = irqd_get_trigger_type(&desc->irq_data);
 
@@ -1144,6 +1147,11 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 
 	irq_put_desc_unlock(desc, flags);
 }
+
+void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
+{
+	__irq_modify_status(irq, clr, set, _IRQF_MODIFY_MASK);
+}
 EXPORT_SYMBOL_GPL(irq_modify_status);
 
 /**
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index 403378b9947b..51acdf43eadc 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -36,11 +36,17 @@ enum {
 #undef IRQF_MODIFY_MASK
 #define IRQF_MODIFY_MASK	GOT_YOU_MORON
 
+static inline void
+__irq_settings_clr_and_set(struct irq_desc *desc, u32 clr, u32 set, u32 mask)
+{
+	desc->status_use_accessors &= ~(clr & mask);
+	desc->status_use_accessors |= (set & mask);
+}
+
 static inline void
 irq_settings_clr_and_set(struct irq_desc *desc, u32 clr, u32 set)
 {
-	desc->status_use_accessors &= ~(clr & _IRQF_MODIFY_MASK);
-	desc->status_use_accessors |= (set & _IRQF_MODIFY_MASK);
+	__irq_settings_clr_and_set(desc, clr, set, _IRQF_MODIFY_MASK);
 }
 
 static inline bool irq_settings_is_per_cpu(struct irq_desc *desc)
-- 
2.28.0