linux-kernel - [PATCH v1 2/2] genirq/irqdesc: Balance locking to make sparse happy

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Message-ID: <20250416114122.2191820-3-andriy.shevchenko@linux.intel.com>
Date: Wed, 16 Apr 2025 14:40:34 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v1 2/2] genirq/irqdesc: Balance locking to make sparse happy

Sparse is not happy right now about conditional locking and
complains:

  irqdesc.c:899:17: warning: context imbalance in '__irq_get_desc_lock' - wrong count at exit

Refactor the code and use __acquire() to make it happy.
Annotate the function that it acquires the lock in the
similar way how __irq_put_desc_unlock() is marked.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 kernel/irq/irqdesc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 0afc2b0b03be..cecff0cb13eb 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -899,21 +899,22 @@ unsigned int irq_get_next_irq(unsigned int offset)
 struct irq_desc *
 __irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
 		    unsigned int check)
+	__acquires(&desc->lock)
 {
 	struct irq_desc *desc;
 
 	desc = irq_to_desc(irq);
 	if (!desc)
-		return NULL;
+		goto lock;
 
 	if (check & _IRQ_DESC_CHECK) {
 		if ((check & _IRQ_DESC_PERCPU) &&
 		    !irq_settings_is_per_cpu_devid(desc))
-			return NULL;
+			goto lock;
 
 		if (!(check & _IRQ_DESC_PERCPU) &&
 		    irq_settings_is_per_cpu_devid(desc))
-			return NULL;
+			goto lock;
 	}
 
 	if (bus)
@@ -921,6 +922,10 @@ __irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
 	raw_spin_lock_irqsave(&desc->lock, *flags);
 
 	return desc;
+
+lock:
+	__acquire(&desc->lock);
+	return NULL;
 }
 
 void __irq_put_desc_unlock(struct irq_desc *desc, unsigned long flags, bool bus)
-- 
2.47.2