Merge branch 'for-5.1/nfit/ars' into libnvdimm-for-next

Merge several updates to the ARS implementation. Highlights include:

* Support retrieval of short-ARS results if the ARS state is "requires
  continuation", and even if the "no_init_ars" module parameter is
  specified.
* Allow busy-polling of the kernel ARS state by allowing root to reset
  the exponential back-off timer.
* Filter potentially stale ARS results by tracking query-ARS relative to
  the previous start-ARS.

2 files changed, 57 insertions, 24 deletions

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index c7afb1f223f7..df8979008dd4 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1323,19 +1323,30 @@ static ssize_t scrub_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nvdimm_bus_descriptor *nd_desc;
+	struct acpi_nfit_desc *acpi_desc;
 	ssize_t rc = -ENXIO;
+	bool busy;
 
 	device_lock(dev);
 	nd_desc = dev_get_drvdata(dev);
-	if (nd_desc) {
-		struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
+	if (!nd_desc) {
+		device_unlock(dev);
+		return rc;
+	}
+	acpi_desc = to_acpi_desc(nd_desc);
 
-		mutex_lock(&acpi_desc->init_mutex);
-		rc = sprintf(buf, "%d%s", acpi_desc->scrub_count,
-				acpi_desc->scrub_busy
-				&& !acpi_desc->cancel ? "+\n" : "\n");
-		mutex_unlock(&acpi_desc->init_mutex);
+	mutex_lock(&acpi_desc->init_mutex);
+	busy = test_bit(ARS_BUSY, &acpi_desc->scrub_flags)
+		&& !test_bit(ARS_CANCEL, &acpi_desc->scrub_flags);
+	rc = sprintf(buf, "%d%s", acpi_desc->scrub_count, busy ? "+\n" : "\n");
+	/* Allow an admin to poll the busy state at a higher rate */
+	if (busy && capable(CAP_SYS_RAWIO) && !test_and_set_bit(ARS_POLL,
+				&acpi_desc->scrub_flags)) {
+		acpi_desc->scrub_tmo = 1;
+		mod_delayed_work(nfit_wq, &acpi_desc->dwork, HZ);
 	}
+
+	mutex_unlock(&acpi_desc->init_mutex);
 	device_unlock(dev);
 	return rc;
 }
@@ -2681,7 +2692,10 @@ static int ars_start(struct acpi_nfit_desc *acpi_desc,
 
 	if (rc < 0)
 		return rc;
-	return cmd_rc;
+	if (cmd_rc < 0)
+		return cmd_rc;
+	set_bit(ARS_VALID, &acpi_desc->scrub_flags);
+	return 0;
 }
 
 static int ars_continue(struct acpi_nfit_desc *acpi_desc)
@@ -2691,11 +2705,11 @@ static int ars_continue(struct acpi_nfit_desc *acpi_desc)
 	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
 	struct nd_cmd_ars_status *ars_status = acpi_desc->ars_status;
 
-	memset(&ars_start, 0, sizeof(ars_start));
-	ars_start.address = ars_status->restart_address;
-	ars_start.length = ars_status->restart_length;
-	ars_start.type = ars_status->type;
-	ars_start.flags = acpi_desc->ars_start_flags;
+	ars_start = (struct nd_cmd_ars_start) {
+		.address = ars_status->restart_address,
+		.length = ars_status->restart_length,
+		.type = ars_status->type,
+	};
 	rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_START, &ars_start,
 			sizeof(ars_start), &cmd_rc);
 	if (rc < 0)
@@ -2774,6 +2788,17 @@ static int ars_status_process_records(struct acpi_nfit_desc *acpi_desc)
 	 */
 	if (ars_status->out_length < 44)
 		return 0;
+
+	/*
+	 * Ignore potentially stale results that are only refreshed
+	 * after a start-ARS event.
+	 */
+	if (!test_and_clear_bit(ARS_VALID, &acpi_desc->scrub_flags)) {
+		dev_dbg(acpi_desc->dev, "skip %d stale records\n",
+				ars_status->num_records);
+		return 0;
+	}
+
 	for (i = 0; i < ars_status->num_records; i++) {
 		/* only process full records */
 		if (ars_status->out_length
@@ -3044,14 +3069,16 @@ static int ars_register(struct acpi_nfit_desc *acpi_desc,
 {
 	int rc;
 
-	if (no_init_ars || test_bit(ARS_FAILED, &nfit_spa->ars_state))
+	if (test_bit(ARS_FAILED, &nfit_spa->ars_state))
 		return acpi_nfit_register_region(acpi_desc, nfit_spa);
 
 	set_bit(ARS_REQ_SHORT, &nfit_spa->ars_state);
-	set_bit(ARS_REQ_LONG, &nfit_spa->ars_state);
+	if (!no_init_ars)
+		set_bit(ARS_REQ_LONG, &nfit_spa->ars_state);
 
 	switch (acpi_nfit_query_poison(acpi_desc)) {
 	case 0:
+	case -ENOSPC:
 	case -EAGAIN:
 		rc = ars_start(acpi_desc, nfit_spa, ARS_REQ_SHORT);
 		/* shouldn't happen, try again later */
@@ -3076,7 +3103,6 @@ static int ars_register(struct acpi_nfit_desc *acpi_desc,
 		break;
 	case -EBUSY:
 	case -ENOMEM:
-	case -ENOSPC:
 		/*
 		 * BIOS was using ARS, wait for it to complete (or
 		 * resources to become available) and then perform our
@@ -3111,7 +3137,7 @@ static unsigned int __acpi_nfit_scrub(struct acpi_nfit_desc *acpi_desc,
 
 	lockdep_assert_held(&acpi_desc->init_mutex);
 
-	if (acpi_desc->cancel)
+	if (test_bit(ARS_CANCEL, &acpi_desc->scrub_flags))
 		return 0;
 
 	if (query_rc == -EBUSY) {
@@ -3185,7 +3211,7 @@ 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;
+	set_bit(ARS_BUSY, &acpi_desc->scrub_flags);
 	/* note this should only be set from within the workqueue */
 	if (tmo)
 		acpi_desc->scrub_tmo = tmo;
@@ -3201,7 +3227,7 @@ static void notify_ars_done(struct acpi_nfit_desc *acpi_desc)
 {
 	lockdep_assert_held(&acpi_desc->init_mutex);
 
-	acpi_desc->scrub_busy = 0;
+	clear_bit(ARS_BUSY, &acpi_desc->scrub_flags);
 	acpi_desc->scrub_count++;
 	if (acpi_desc->scrub_count_state)
 		sysfs_notify_dirent(acpi_desc->scrub_count_state);
@@ -3222,6 +3248,7 @@ static void acpi_nfit_scrub(struct work_struct *work)
 	else
 		notify_ars_done(acpi_desc);
 	memset(acpi_desc->ars_status, 0, acpi_desc->max_ars);
+	clear_bit(ARS_POLL, &acpi_desc->scrub_flags);
 	mutex_unlock(&acpi_desc->init_mutex);
 }
 
@@ -3256,6 +3283,7 @@ static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc)
 	struct nfit_spa *nfit_spa;
 	int rc;
 
+	set_bit(ARS_VALID, &acpi_desc->scrub_flags);
 	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
 		switch (nfit_spa_type(nfit_spa->spa)) {
 		case NFIT_SPA_VOLATILE:
@@ -3490,7 +3518,7 @@ int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc,
 	struct nfit_spa *nfit_spa;
 
 	mutex_lock(&acpi_desc->init_mutex);
-	if (acpi_desc->cancel) {
+	if (test_bit(ARS_CANCEL, &acpi_desc->scrub_flags)) {
 		mutex_unlock(&acpi_desc->init_mutex);
 		return 0;
 	}
@@ -3569,7 +3597,7 @@ void acpi_nfit_shutdown(void *data)
 	mutex_unlock(&acpi_desc_lock);
 
 	mutex_lock(&acpi_desc->init_mutex);
-	acpi_desc->cancel = 1;
+	set_bit(ARS_CANCEL, &acpi_desc->scrub_flags);
 	cancel_delayed_work_sync(&acpi_desc->dwork);
 	mutex_unlock(&acpi_desc->init_mutex);
 
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index 4de167b4f76f..2f8cf2a11e3b 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -214,6 +214,13 @@ struct nfit_mem {
 	int family;
 };
 
+enum scrub_flags {
+	ARS_BUSY,
+	ARS_CANCEL,
+	ARS_VALID,
+	ARS_POLL,
+};
+
 struct acpi_nfit_desc {
 	struct nvdimm_bus_descriptor nd_desc;
 	struct acpi_table_header acpi_header;
@@ -227,7 +234,6 @@ struct acpi_nfit_desc {
 	struct list_head idts;
 	struct nvdimm_bus *nvdimm_bus;
 	struct device *dev;
-	u8 ars_start_flags;
 	struct nd_cmd_ars_status *ars_status;
 	struct nfit_spa *scrub_spa;
 	struct delayed_work dwork;
@@ -236,8 +242,7 @@ 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 scrub_flags;
 	unsigned long dimm_cmd_force_en;
 	unsigned long bus_cmd_force_en;
 	unsigned long bus_nfit_cmd_force_en;