vfio/pci: Move to single error path

Enabling and disabling of an interrupt involves several steps
that can fail. Cleanup after failure is done when the error
is encountered, resulting in some repetitive code.

Support for dynamic contexts will introduce more steps during
interrupt enabling and disabling.

Transition to centralized exit path in preparation for dynamic
contexts to eliminate duplicate error handling code.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/72dddae8aa710ce522a74130120733af61cffe4d.1683740667.git.reinette.chatre@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/pci/vfio_pci_intrs.c

@@ -427,8 +427,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 
 	trigger = eventfd_ctx_fdget(fd);
 	if (IS_ERR(trigger)) {
-		kfree(ctx->name);
-		return PTR_ERR(trigger);
+		ret = PTR_ERR(trigger);
+		goto out_free_name;
 	}
 
 	/*
@@ -448,11 +448,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 
 	ret = request_irq(irq, vfio_msihandler, 0, ctx->name, trigger);
 	vfio_pci_memory_unlock_and_restore(vdev, cmd);
-	if (ret) {
-		kfree(ctx->name);
-		eventfd_ctx_put(trigger);
-		return ret;
-	}
+	if (ret)
+		goto out_put_eventfd_ctx;
 
 	ctx->producer.token = trigger;
 	ctx->producer.irq = irq;
@@ -467,6 +464,12 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 	ctx->trigger = trigger;
 
 	return 0;
+
+out_put_eventfd_ctx:
+	eventfd_ctx_put(trigger);
+out_free_name:
+	kfree(ctx->name);
+	return ret;
 }
 
 static int vfio_msi_set_block(struct vfio_pci_core_device *vdev, unsigned start,