Normally, an ARS (Address Range Scrub) only happens at
boot/initialization time. There can however arise situations where a
bus-wide rescan is needed - notably, in the case of discovering a latent
media error, we should do a full rescan to figure out what other sectors
are bad, and thus potentially avoid triggering an mce on them in the
future. Also provide a sysfs trigger to start a bus-wide scrub.

Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Cc: <linux-a...@vger.kernel.org>
Cc: <linux-nvd...@lists.01.org>
Signed-off-by: Vishal Verma <vishal.l.ve...@intel.com>
---
 drivers/acpi/nfit.c              | 123 +++++++++++++++++++++++++++++++++------
 drivers/acpi/nfit.h              |   4 +-
 drivers/nvdimm/core.c            |   7 +++
 include/linux/libnvdimm.h        |   1 +
 tools/testing/nvdimm/test/nfit.c |  16 +++++
 5 files changed, 131 insertions(+), 20 deletions(-)

diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index ac6ddcc0..4e65255 100644
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/ndctl.h>
+#include <linux/sysfs.h>
 #include <linux/delay.h>
 #include <linux/list.h>
 #include <linux/acpi.h>
@@ -806,8 +807,41 @@ static ssize_t revision_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(revision);
 
+/*
+ * This shows the number of full Address Range Scrubs that have been
+ * completed since driver load time. Userspace can wait on this using
+ * select/poll etc.
+ */
+static ssize_t scrub_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 = to_nd_desc(nvdimm_bus);
+       struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
+
+       return sprintf(buf, "%d\n", acpi_desc->scrub_count);
+}
+
+static int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc);
+
+static ssize_t scrub_store(struct device *dev,
+               struct device_attribute *attr, const char *buf, size_t size)
+{
+       struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);
+       struct nvdimm_bus_descriptor *nd_desc = to_nd_desc(nvdimm_bus);
+       struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
+       int rc;
+
+       rc = acpi_nfit_ars_rescan(acpi_desc);
+       if (rc)
+               return rc;
+       return size;
+}
+static DEVICE_ATTR_RW(scrub);
+
 static struct attribute *acpi_nfit_attributes[] = {
        &dev_attr_revision.attr,
+       &dev_attr_scrub.attr,
        NULL,
 };
 
@@ -2138,7 +2172,7 @@ static void acpi_nfit_async_scrub(struct acpi_nfit_desc 
*acpi_desc,
        unsigned int tmo = scrub_timeout;
        int rc;
 
-       if (nfit_spa->ars_done || !nfit_spa->nd_region)
+       if (!(nfit_spa->ars_required && nfit_spa->nd_region))
                return;
 
        rc = ars_start(acpi_desc, nfit_spa);
@@ -2227,7 +2261,9 @@ static void acpi_nfit_scrub(struct work_struct *work)
         * firmware initiated scrubs to complete and then we go search for the
         * affected spa regions to mark them scanned.  In the second phase we
         * initiate a directed scrub for every range that was not scrubbed in
-        * phase 1.
+        * phase 1. If we're called for a 'rescan', we harmlessly pass through
+        * the first phase, but really only care about running phase 2, where
+        * regions can be notified of new poison.
         */
 
        /* process platform firmware initiated scrubs */
@@ -2330,14 +2366,17 @@ static void acpi_nfit_scrub(struct work_struct *work)
                 * Flag all the ranges that still need scrubbing, but
                 * register them now to make data available.
                 */
-               if (nfit_spa->nd_region)
-                       nfit_spa->ars_done = 1;
-               else
+               if (!nfit_spa->nd_region) {
+                       nfit_spa->ars_required = 1;
                        acpi_nfit_register_region(acpi_desc, nfit_spa);
+               }
        }
 
        list_for_each_entry(nfit_spa, &acpi_desc->spas, list)
                acpi_nfit_async_scrub(acpi_desc, nfit_spa);
+       acpi_desc->scrub_count++;
+       if (acpi_desc->scrub_count_state)
+               sysfs_notify_dirent(acpi_desc->scrub_count_state);
        mutex_unlock(&acpi_desc->init_mutex);
 }
 
@@ -2495,6 +2534,27 @@ static int acpi_nfit_clear_to_send(struct 
nvdimm_bus_descriptor *nd_desc,
        return 0;
 }
 
+static int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc)
+{
+       struct device *dev = acpi_desc->dev;
+       struct nfit_spa *nfit_spa;
+
+       if (work_busy(&acpi_desc->work))
+               return -EBUSY;
+
+       list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
+               struct acpi_nfit_system_address *spa = nfit_spa->spa;
+
+               if (nfit_spa_type(spa) != NFIT_SPA_PM)
+                       continue;
+
+               nfit_spa->ars_required = 1;
+       }
+       queue_work(nfit_wq, &acpi_desc->work);
+       dev_info(dev, "%s: ars_scan triggered\n", __func__);
+       return 0;
+}
+
 void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev)
 {
        struct nvdimm_bus_descriptor *nd_desc;
@@ -2523,6 +2583,37 @@ void acpi_nfit_desc_init(struct acpi_nfit_desc 
*acpi_desc, struct device *dev)
 }
 EXPORT_SYMBOL_GPL(acpi_nfit_desc_init);
 
+static struct acpi_nfit_desc *acpi_nfit_desc_alloc_register(struct device *dev)
+{
+       struct acpi_nfit_desc *acpi_desc;
+       struct kernfs_node *nfit;
+       struct device *bus_dev;
+
+       acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
+       if (!acpi_desc)
+               return ERR_PTR(-ENOMEM);
+
+       acpi_nfit_desc_init(acpi_desc, dev);
+
+       acpi_desc->nvdimm_bus = nvdimm_bus_register(dev, &acpi_desc->nd_desc);
+       if (!acpi_desc->nvdimm_bus)
+               return ERR_PTR(-ENOMEM);
+
+       bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
+       nfit = sysfs_get_dirent(bus_dev->kobj.sd, "nfit");
+       if (!nfit) {
+               dev_err(dev, "sysfs_get_dirent 'nfit' failed\n");
+               return ERR_PTR(-ENODEV);
+       }
+       acpi_desc->scrub_count_state = sysfs_get_dirent(nfit, "scrub");
+       if (!acpi_desc->scrub_count_state) {
+               dev_err(dev, "sysfs_get_dirent 'scrub' failed\n");
+               return ERR_PTR(-ENODEV);
+       }
+
+       return acpi_desc;
+}
+
 static int acpi_nfit_add(struct acpi_device *adev)
 {
        struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -2540,13 +2631,9 @@ static int acpi_nfit_add(struct acpi_device *adev)
                return 0;
        }
 
-       acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
-       if (!acpi_desc)
-               return -ENOMEM;
-       acpi_nfit_desc_init(acpi_desc, &adev->dev);
-       acpi_desc->nvdimm_bus = nvdimm_bus_register(dev, &acpi_desc->nd_desc);
-       if (!acpi_desc->nvdimm_bus)
-               return -ENOMEM;
+       acpi_desc = acpi_nfit_desc_alloc_register(dev);
+       if (IS_ERR(acpi_desc))
+               return PTR_ERR(acpi_desc);
 
        /*
         * Save the acpi header for later and then skip it,
@@ -2587,6 +2674,7 @@ static int acpi_nfit_remove(struct acpi_device *adev)
 
        acpi_desc->cancel = 1;
        flush_workqueue(nfit_wq);
+       sysfs_put(acpi_desc->scrub_count_state);
        nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
        return 0;
 }
@@ -2611,13 +2699,10 @@ static void acpi_nfit_notify(struct acpi_device *adev, 
u32 event)
        }
 
        if (!acpi_desc) {
-               acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
-               if (!acpi_desc)
-                       goto out_unlock;
-               acpi_nfit_desc_init(acpi_desc, &adev->dev);
-               acpi_desc->nvdimm_bus = nvdimm_bus_register(dev, 
&acpi_desc->nd_desc);
-               if (!acpi_desc->nvdimm_bus)
-                       goto out_unlock;
+               acpi_desc = acpi_nfit_desc_alloc_register(dev);
+               if (IS_ERR(acpi_desc))
+                       dev_err(dev, "%s: failed to alloc acpi_desc (%ld)\n",
+                               __func__, PTR_ERR(acpi_desc));
        } else {
                /*
                 * Finish previous registration before considering new
diff --git a/drivers/acpi/nfit.h b/drivers/acpi/nfit.h
index 02b9ea1..954d2aa 100644
--- a/drivers/acpi/nfit.h
+++ b/drivers/acpi/nfit.h
@@ -77,7 +77,7 @@ struct nfit_spa {
        struct acpi_nfit_system_address *spa;
        struct list_head list;
        struct nd_region *nd_region;
-       unsigned int ars_done:1;
+       unsigned int ars_required:1;
        u32 clear_err_unit;
        u32 max_ars;
 };
@@ -146,6 +146,8 @@ struct acpi_nfit_desc {
        struct nd_cmd_ars_status *ars_status;
        size_t ars_status_size;
        struct work_struct work;
+       struct kernfs_node *scrub_count_state;
+       unsigned int scrub_count;
        unsigned int cancel:1;
        unsigned long dimm_cmd_force_en;
        unsigned long bus_cmd_force_en;
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index be89764..d81db3ac 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -99,6 +99,13 @@ struct nvdimm_bus_descriptor *to_nd_desc(struct nvdimm_bus 
*nvdimm_bus)
 }
 EXPORT_SYMBOL_GPL(to_nd_desc);
 
+struct device *to_nvdimm_bus_dev(struct nvdimm_bus *nvdimm_bus)
+{
+       /* struct nvdimm_bus definition is private to libnvdimm */
+       return &nvdimm_bus->dev;
+}
+EXPORT_SYMBOL_GPL(to_nvdimm_bus_dev);
+
 struct nvdimm_bus *walk_to_nvdimm_bus(struct device *nd_dev)
 {
        struct device *dev;
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index 0c3c30c..27cecc2 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -129,6 +129,7 @@ struct nvdimm *to_nvdimm(struct device *dev);
 struct nd_region *to_nd_region(struct device *dev);
 struct nd_blk_region *to_nd_blk_region(struct device *dev);
 struct nvdimm_bus_descriptor *to_nd_desc(struct nvdimm_bus *nvdimm_bus);
+struct device *to_nvdimm_bus_dev(struct nvdimm_bus *nvdimm_bus);
 const char *nvdimm_name(struct nvdimm *nvdimm);
 unsigned long nvdimm_cmd_mask(struct nvdimm *nvdimm);
 void *nvdimm_provider_data(struct nvdimm *nvdimm);
diff --git a/tools/testing/nvdimm/test/nfit.c b/tools/testing/nvdimm/test/nfit.c
index c919866..74231de 100644
--- a/tools/testing/nvdimm/test/nfit.c
+++ b/tools/testing/nvdimm/test/nfit.c
@@ -20,6 +20,7 @@
 #include <linux/mutex.h>
 #include <linux/ndctl.h>
 #include <linux/sizes.h>
+#include <linux/sysfs.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <nfit.h>
@@ -1409,6 +1410,8 @@ static int nfit_test_probe(struct platform_device *pdev)
        struct acpi_nfit_desc *acpi_desc;
        struct device *dev = &pdev->dev;
        struct nfit_test *nfit_test;
+       struct kernfs_node *nfit;
+       struct device *bus_dev;
        int rc;
 
        nfit_test = to_nfit_test(&pdev->dev);
@@ -1471,6 +1474,18 @@ static int nfit_test_probe(struct platform_device *pdev)
        if (!acpi_desc->nvdimm_bus)
                return -ENXIO;
 
+       bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
+       nfit = sysfs_get_dirent(bus_dev->kobj.sd, "nfit");
+       if (!nfit) {
+               dev_err(dev, "sysfs_get_dirent 'nfit' failed\n");
+               return -ENODEV;
+       }
+       acpi_desc->scrub_count_state = sysfs_get_dirent(nfit, "scrub");
+       if (!acpi_desc->scrub_count_state) {
+               dev_err(dev, "sysfs_get_dirent 'scrub' failed\n");
+               return -ENODEV;
+       }
+
        rc = acpi_nfit_init(acpi_desc, nfit_test->nfit_size);
        if (rc) {
                nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
@@ -1497,6 +1512,7 @@ static int nfit_test_remove(struct platform_device *pdev)
        struct nfit_test *nfit_test = to_nfit_test(&pdev->dev);
        struct acpi_nfit_desc *acpi_desc = &nfit_test->acpi_desc;
 
+       sysfs_put(acpi_desc->scrub_count_state);
        nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
 
        return 0;
-- 
2.7.4

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