acpi, nfit: limit ->flush_probe() to initialization work

The nvdimm probe flushing mechanism gives userspace a sync point where
it knows all asynchronous driver probe sequences have completed.
However, it need not wait for other asynchronous actions, like
on-demand address-range-scrub. Track the init work separately from other
work in the workqueue, and only flush the former.

Signed-off-by: Dan Williams <[e-mail]>

drivers/acpi/nfit/core.c

···
 			acpi_nfit_register_region(acpi_desc, nfit_spa);
 		}
 	}
+	acpi_desc->init_complete = 1;
 
 	list_for_each_entry(nfit_spa, &acpi_desc->spas, list)
 		acpi_nfit_async_scrub(acpi_desc, nfit_spa);
···
 	/* bounce the device lock to flush acpi_nfit_add / acpi_nfit_notify */
 	device_lock(dev);
 	device_unlock(dev);
+
+	/* bounce the init_mutex to make init_complete valid */
+	mutex_lock(&acpi_desc->init_mutex);
+	mutex_unlock(&acpi_desc->init_mutex);
+	if (acpi_desc->init_complete)
+		return 0;
 
 	/*
 	 * Scrub work could take 10s of seconds, userspace may give up so we

drivers/acpi/nfit/nfit.h

···
 	unsigned int scrub_count;
 	unsigned int scrub_mode;
 	unsigned int cancel:1;
+	unsigned int init_complete:1;
 	unsigned long dimm_cmd_force_en;
 	unsigned long bus_cmd_force_en;
 	int (*blk_do_io)(struct nd_blk_region *ndbr, resource_size_t dpa,