genirq/manage: Rework can_request_irq()

Use the new guards to get and lock the interrupt descriptor and tidy up the
code.

Make the return value boolean to reflect it's meaning.

No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

Author: KAGA-KOKO

include/linux/irq.h

@@ -700,7 +700,7 @@ extern void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret);
 extern int noirqdebug_setup(char *str);
 
 /* Checks whether the interrupt can be requested by request_irq(): */
-extern int can_request_irq(unsigned int irq, unsigned long irqflags);
+extern bool can_request_irq(unsigned int irq, unsigned long irqflags);
 
 /* Dummy irq-chip implementations: */
 extern struct irq_chip no_irq_chip;

kernel/irq/manage.c

@@ -888,22 +888,17 @@ EXPORT_SYMBOL(irq_set_irq_wake);
  * particular irq has been exclusively allocated or is available
  * for driver use.
  */
-int can_request_irq(unsigned int irq, unsigned long irqflags)
+bool can_request_irq(unsigned int irq, unsigned long irqflags)
 {
-	unsigned long flags;
-	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
-	int canrequest = 0;
-
-	if (!desc)
-		return 0;
+	scoped_irqdesc_get_and_lock(irq, IRQ_GET_DESC_CHECK_GLOBAL) {
+		struct irq_desc *desc = scoped_irqdesc;
 
-	if (irq_settings_can_request(desc)) {
-		if (!desc->action ||
-		    irqflags & desc->action->flags & IRQF_SHARED)
-			canrequest = 1;
+		if (irq_settings_can_request(desc)) {
+			if (!desc->action || irqflags & desc->action->flags & IRQF_SHARED)
+				return true;
+		}
 	}
-	irq_put_desc_unlock(desc, flags);
-	return canrequest;
+	return false;
 }
 
 int __irq_set_trigger(struct irq_desc *desc, unsigned long flags)