genirq: Separate activation and startup

Activation of an interrupt and startup are currently a combo
functionlity. That works so far, but upcoming changes require a strict
separation because the activation can fail in future.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Yu Chen <yu.c.chen@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: https://lkml.kernel.org/r/20170913213152.754334077@linutronix.de

kernel/irq/autoprobe.c

@@ -53,7 +53,7 @@ unsigned long probe_irq_on(void)
 			if (desc->irq_data.chip->irq_set_type)
 				desc->irq_data.chip->irq_set_type(&desc->irq_data,
 							 IRQ_TYPE_PROBE);
-			irq_startup(desc, IRQ_NORESEND, IRQ_START_FORCE);
+			irq_activate_and_startup(desc, IRQ_NORESEND);
 		}
 		raw_spin_unlock_irq(&desc->lock);
 	}

kernel/irq/chip.c

@@ -207,20 +207,19 @@ __irq_startup_managed(struct irq_desc *desc, struct cpumask *aff, bool force)
 		 * Catch code which fiddles with enable_irq() on a managed
 		 * and potentially shutdown IRQ. Chained interrupt
 		 * installment or irq auto probing should not happen on
-		 * managed irqs either. Emit a warning, break the affinity
-		 * and start it up as a normal interrupt.
+		 * managed irqs either.
 		 */
 		if (WARN_ON_ONCE(force))
-			return IRQ_STARTUP_NORMAL;
+			return IRQ_STARTUP_ABORT;
 		/*
 		 * The interrupt was requested, but there is no online CPU
 		 * in it's affinity mask. Put it into managed shutdown
 		 * state and let the cpu hotplug mechanism start it up once
 		 * a CPU in the mask becomes available.
 		 */
-		irqd_set_managed_shutdown(d);
 		return IRQ_STARTUP_ABORT;
 	}
+	irq_domain_activate_irq(d);
 	return IRQ_STARTUP_MANAGED;
 }
 #else
@@ -236,7 +235,9 @@ static int __irq_startup(struct irq_desc *desc)
 	struct irq_data *d = irq_desc_get_irq_data(desc);
 	int ret = 0;
 
-	irq_domain_activate_irq(d);
+	/* Warn if this interrupt is not activated but try nevertheless */
+	WARN_ON_ONCE(!irqd_is_activated(d));
+
 	if (d->chip->irq_startup) {
 		ret = d->chip->irq_startup(d);
 		irq_state_clr_disabled(desc);
@@ -269,6 +270,7 @@ int irq_startup(struct irq_desc *desc, bool resend, bool force)
 			irq_set_affinity_locked(d, aff, false);
 			break;
 		case IRQ_STARTUP_ABORT:
+			irqd_set_managed_shutdown(d);
 			return 0;
 		}
 	}
@@ -278,6 +280,22 @@ int irq_startup(struct irq_desc *desc, bool resend, bool force)
 	return ret;
 }
 
+int irq_activate(struct irq_desc *desc)
+{
+	struct irq_data *d = irq_desc_get_irq_data(desc);
+
+	if (!irqd_affinity_is_managed(d))
+		irq_domain_activate_irq(d);
+	return 0;
+}
+
+void irq_activate_and_startup(struct irq_desc *desc, bool resend)
+{
+	if (WARN_ON(irq_activate(desc)))
+		return;
+	irq_startup(desc, resend, IRQ_START_FORCE);
+}
+
 static void __irq_disable(struct irq_desc *desc, bool mask);
 
 void irq_shutdown(struct irq_desc *desc)
@@ -953,7 +971,7 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle,
 		irq_settings_set_norequest(desc);
 		irq_settings_set_nothread(desc);
 		desc->action = &chained_action;
-		irq_startup(desc, IRQ_RESEND, IRQ_START_FORCE);
+		irq_activate_and_startup(desc, IRQ_RESEND);
 	}
 }
 

kernel/irq/internals.h

@@ -74,6 +74,8 @@ extern void __enable_irq(struct irq_desc *desc);
 #define IRQ_START_FORCE	true
 #define IRQ_START_COND	false
 
+extern int irq_activate(struct irq_desc *desc);
+extern void irq_activate_and_startup(struct irq_desc *desc, bool resend);
 extern int irq_startup(struct irq_desc *desc, bool resend, bool force);
 
 extern void irq_shutdown(struct irq_desc *desc);

kernel/irq/manage.c

@@ -519,7 +519,7 @@ void __enable_irq(struct irq_desc *desc)
 		 * time. If it was already started up, then irq_startup()
 		 * will invoke irq_enable() under the hood.
 		 */
-		irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
+		irq_startup(desc, IRQ_RESEND, IRQ_START_FORCE);
 		break;
 	}
 	default:
@@ -1325,6 +1325,21 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 				goto out_unlock;
 		}
 
+		/*
+		 * Activate the interrupt. That activation must happen
+		 * independently of IRQ_NOAUTOEN. request_irq() can fail
+		 * and the callers are supposed to handle
+		 * that. enable_irq() of an interrupt requested with
+		 * IRQ_NOAUTOEN is not supposed to fail. The activation
+		 * keeps it in shutdown mode, it merily associates
+		 * resources if necessary and if that's not possible it
+		 * fails. Interrupts which are in managed shutdown mode
+		 * will simply ignore that activation request.
+		 */
+		ret = irq_activate(desc);
+		if (ret)
+			goto out_unlock;
+
 		desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
 				  IRQS_ONESHOT | IRQS_WAITING);
 		irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);