[PATCH 5/8] nfit, libnvdimm: async region scrub workqueue

From: Dan Williams
Date: Tue Feb 23 2016 - 21:17:56 EST


Introduce a workqueue that will be used to run address range scrub
asynchronously with the rest of nvdimm device probing.

Userspace still wants notification when probing operations complete, so
introduce a new callback to flush this workqueue when userspace is
awaiting probe completion.

Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/acpi/nfit.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
drivers/acpi/nfit.h | 3 +++
drivers/nvdimm/core.c | 9 ++++++++
include/linux/libnvdimm.h | 1 +
4 files changed, 62 insertions(+)

diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index 76c9444c9c60..4aa2bd54fc1d 100644
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -34,6 +34,8 @@ static bool force_enable_dimms;
module_param(force_enable_dimms, bool, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(force_enable_dimms, "Ignore _STA (ACPI DIMM device) status");

+static struct workqueue_struct *nfit_wq;
+
struct nfit_table_prev {
struct list_head spas;
struct list_head memdevs;
@@ -1961,6 +1963,39 @@ int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz)
}
EXPORT_SYMBOL_GPL(acpi_nfit_init);

+struct acpi_nfit_flush_work {
+ struct work_struct work;
+ struct completion cmp;
+};
+
+static void flush_probe(struct work_struct *work)
+{
+ struct acpi_nfit_flush_work *flush;
+
+ flush = container_of(work, typeof(*flush), work);
+ complete(&flush->cmp);
+}
+
+static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
+{
+ struct acpi_nfit_desc *acpi_desc = to_acpi_nfit_desc(nd_desc);
+ struct device *dev = acpi_desc->dev;
+ struct acpi_nfit_flush_work flush;
+
+ /* bounce the device lock to flush acpi_nfit_add / acpi_nfit_notify */
+ device_lock(dev);
+ device_unlock(dev);
+
+ /*
+ * Scrub work could take 10s of seconds, userspace may give up so we
+ * need to be interruptible while waiting.
+ */
+ INIT_WORK_ONSTACK(&flush.work, flush_probe);
+ COMPLETION_INITIALIZER_ONSTACK(flush.cmp);
+ queue_work(nfit_wq, &flush.work);
+ return wait_for_completion_interruptible(&flush.cmp);
+}
+
void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev)
{
struct nvdimm_bus_descriptor *nd_desc;
@@ -1971,6 +2006,7 @@ void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev)
nd_desc = &acpi_desc->nd_desc;
nd_desc->provider_name = "ACPI.NFIT";
nd_desc->ndctl = acpi_nfit_ctl;
+ nd_desc->flush_probe = acpi_nfit_flush_probe;
nd_desc->attr_groups = acpi_nfit_attribute_groups;

INIT_LIST_HEAD(&acpi_desc->spa_maps);
@@ -2048,6 +2084,8 @@ static int acpi_nfit_remove(struct acpi_device *adev)
{
struct acpi_nfit_desc *acpi_desc = dev_get_drvdata(&adev->dev);

+ acpi_desc->cancel = 1;
+ flush_workqueue(nfit_wq);
nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
return 0;
}
@@ -2079,6 +2117,12 @@ static void acpi_nfit_notify(struct acpi_device *adev, u32 event)
acpi_desc->nvdimm_bus = nvdimm_bus_register(dev, &acpi_desc->nd_desc);
if (!acpi_desc->nvdimm_bus)
goto out_unlock;
+ } else {
+ /*
+ * Finish previous registration before considering new
+ * regions.
+ */
+ flush_workqueue(nfit_wq);
}

/* Evaluate _FIT */
@@ -2146,12 +2190,17 @@ static __init int nfit_init(void)
acpi_str_to_uuid(UUID_NFIT_BUS, nfit_uuid[NFIT_DEV_BUS]);
acpi_str_to_uuid(UUID_NFIT_DIMM, nfit_uuid[NFIT_DEV_DIMM]);

+ nfit_wq = create_singlethread_workqueue("nfit");
+ if (!nfit_wq)
+ return -ENOMEM;
+
return acpi_bus_register_driver(&acpi_nfit_driver);
}

static __exit void nfit_exit(void)
{
acpi_bus_unregister_driver(&acpi_nfit_driver);
+ destroy_workqueue(nfit_wq);
}

module_init(nfit_init);
diff --git a/drivers/acpi/nfit.h b/drivers/acpi/nfit.h
index 524dec0a3adb..e8388fee4cc6 100644
--- a/drivers/acpi/nfit.h
+++ b/drivers/acpi/nfit.h
@@ -14,6 +14,7 @@
*/
#ifndef __NFIT_H__
#define __NFIT_H__
+#include <linux/workqueue.h>
#include <linux/libnvdimm.h>
#include <linux/types.h>
#include <linux/uuid.h>
@@ -123,6 +124,8 @@ struct acpi_nfit_desc {
struct list_head idts;
struct nvdimm_bus *nvdimm_bus;
struct device *dev;
+ struct work_struct work;
+ unsigned int cancel:1;
unsigned long dimm_dsm_force_en;
unsigned long bus_dsm_force_en;
int (*blk_do_io)(struct nd_blk_region *ndbr, resource_size_t dpa,
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index f309e6bf6833..79646d0c3277 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -298,6 +298,15 @@ static int flush_regions_dimms(struct device *dev, void *data)
static ssize_t wait_probe_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
+ struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);
+ struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
+ int rc;
+
+ if (nd_desc->flush_probe) {
+ rc = nd_desc->flush_probe(nd_desc);
+ if (rc)
+ return rc;
+ }
nd_synchronize();
device_for_each_child(dev, NULL, flush_regions_dimms);
return sprintf(buf, "1\n");
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index f398953270d1..2299f8742f7f 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -71,6 +71,7 @@ struct nvdimm_bus_descriptor {
unsigned long dsm_mask;
char *provider_name;
ndctl_fn ndctl;
+ int (*flush_probe)(struct nvdimm_bus_descriptor *nd_desc);
};

struct nd_cmd_desc {