Merge tag 'libnvdimm-fixes-4.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm fixes from Dave Jiang:

 - ensure that a variable passed in by reference to acpi_nfit_ctl is
   always set to a value. An incremental patch is provided due to notice
   from testing in -next. The rest of the commits did not exhibit
   issues.

 - fix a return path in nsio_rw_bytes() that was not returning "bytes
   remain" as expected for the function.

 - address an issue where applications polling on scrub-completion for
   the NVDIMM may falsely wakeup and read the wrong state value and
   cause hang.

 - change the test unit persistent capability attribute to fix up a
   broken assumption in the unit test infrastructure wrt the
   'write_cache' attribute

 - ratelimit dev_info() in the dax device check_vma() function since
   this is easily triggered from userspace

* tag 'libnvdimm-fixes-4.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  nfit: fix unchecked dereference in acpi_nfit_ctl
  acpi, nfit: Fix scrub idle detection
  tools/testing/nvdimm: advertise a write cache for nfit_test
  acpi/nfit: fix cmd_rc for acpi_nfit_ctl to always return a value
  dev-dax: check_vma: ratelimit dev_info-s
  libnvdimm, pmem: Fix memcpy_mcsafe() return code handling in nsio_rw_bytes()

drivers/acpi/nfit/core.c

@@ -408,6 +408,8 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
 	const guid_t *guid;
 	int rc, i;
 
+	if (cmd_rc)
+		*cmd_rc = -EINVAL;
 	func = cmd;
 	if (cmd == ND_CMD_CALL) {
 		call_pkg = buf;
@@ -518,6 +520,8 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
 		 * If we return an error (like elsewhere) then caller wouldn't
 		 * be able to rely upon data returned to make calculation.
 		 */
+		if (cmd_rc)
+			*cmd_rc = 0;
 		return 0;
 	}
 
@@ -1273,7 +1277,7 @@ static ssize_t scrub_show(struct device *dev,
 
 		mutex_lock(&acpi_desc->init_mutex);
 		rc = sprintf(buf, "%d%s", acpi_desc->scrub_count,
-				work_busy(&acpi_desc->dwork.work)
+				acpi_desc->scrub_busy
 				&& !acpi_desc->cancel ? "+\n" : "\n");
 		mutex_unlock(&acpi_desc->init_mutex);
 	}
@@ -2939,6 +2943,32 @@ static unsigned int __acpi_nfit_scrub(struct acpi_nfit_desc *acpi_desc,
 	return 0;
 }
 
+static void __sched_ars(struct acpi_nfit_desc *acpi_desc, unsigned int tmo)
+{
+	lockdep_assert_held(&acpi_desc->init_mutex);
+
+	acpi_desc->scrub_busy = 1;
+	/* note this should only be set from within the workqueue */
+	if (tmo)
+		acpi_desc->scrub_tmo = tmo;
+	queue_delayed_work(nfit_wq, &acpi_desc->dwork, tmo * HZ);
+}
+
+static void sched_ars(struct acpi_nfit_desc *acpi_desc)
+{
+	__sched_ars(acpi_desc, 0);
+}
+
+static void notify_ars_done(struct acpi_nfit_desc *acpi_desc)
+{
+	lockdep_assert_held(&acpi_desc->init_mutex);
+
+	acpi_desc->scrub_busy = 0;
+	acpi_desc->scrub_count++;
+	if (acpi_desc->scrub_count_state)
+		sysfs_notify_dirent(acpi_desc->scrub_count_state);
+}
+
 static void acpi_nfit_scrub(struct work_struct *work)
 {
 	struct acpi_nfit_desc *acpi_desc;
@@ -2949,14 +2979,10 @@ static void acpi_nfit_scrub(struct work_struct *work)
 	mutex_lock(&acpi_desc->init_mutex);
 	query_rc = acpi_nfit_query_poison(acpi_desc);
 	tmo = __acpi_nfit_scrub(acpi_desc, query_rc);
-	if (tmo) {
-		queue_delayed_work(nfit_wq, &acpi_desc->dwork, tmo * HZ);
-		acpi_desc->scrub_tmo = tmo;
-	} else {
-		acpi_desc->scrub_count++;
-		if (acpi_desc->scrub_count_state)
-			sysfs_notify_dirent(acpi_desc->scrub_count_state);
-	}
+	if (tmo)
+		__sched_ars(acpi_desc, tmo);
+	else
+		notify_ars_done(acpi_desc);
 	memset(acpi_desc->ars_status, 0, acpi_desc->max_ars);
 	mutex_unlock(&acpi_desc->init_mutex);
 }
@@ -3037,7 +3063,7 @@ static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc)
 			break;
 		}
 
-	queue_delayed_work(nfit_wq, &acpi_desc->dwork, 0);
+	sched_ars(acpi_desc);
 	return 0;
 }
 
@@ -3239,7 +3265,7 @@ int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc, unsigned long flags)
 		}
 	}
 	if (scheduled) {
-		queue_delayed_work(nfit_wq, &acpi_desc->dwork, 0);
+		sched_ars(acpi_desc);
 		dev_dbg(dev, "ars_scan triggered\n");
 	}
 	mutex_unlock(&acpi_desc->init_mutex);

drivers/acpi/nfit/nfit.h

@@ -203,6 +203,7 @@ struct acpi_nfit_desc {
 	unsigned int max_ars;
 	unsigned int scrub_count;
 	unsigned int scrub_mode;
+	unsigned int scrub_busy:1;
 	unsigned int cancel:1;
 	unsigned long dimm_cmd_force_en;
 	unsigned long bus_cmd_force_en;