[4.19, 5.0 stable PATCH 4/4] nfit/ars: Avoid stale ARS results

From: Dan Williams <dan.j.williams@intel.com>
To: stable@vger.kernel.org
Cc: Krzysztof Rusocki <krzysztof.rusocki@intel.com>,
	linux-nvdimm@lists.01.org
Subject: [4.19, 5.0 stable PATCH 4/4] nfit/ars: Avoid stale ARS results
Date: Mon, 22 Apr 2019 16:08:26 -0700	[thread overview]
Message-ID: <155597450684.2675082.2702598957561878317.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <155597449036.2675082.7035380482732870260.stgit@dwillia2-desk3.amr.corp.intel.com>

commit 78153dd45e7e0596ba32b15d02bda08e1513111e upstream.

Gate ARS result consumption on whether the OS issued start-ARS since the
previous consumption. The BIOS may only clear its result buffers after a
successful start-ARS.

Fixes: 0caeef63e6d2 ("libnvdimm: Add a poison list and export badblocks")
Cc: <stable@vger.kernel.org>
Reported-by: Krzysztof Rusocki <krzysztof.rusocki@intel.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/acpi/nfit/core.c |   17 ++++++++++++++++-
 drivers/acpi/nfit/nfit.h |    1 +
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 61d3fd65fbe9..4be4dc3e8aa6 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2661,7 +2661,10 @@ 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)
@@ -2754,6 +2757,17 @@ 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
@@ -3238,6 +3252,7 @@ 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:
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index d14bad687fb8..0cbe5009eb2c 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -213,6 +213,7 @@ struct nfit_mem {
 enum scrub_flags {
 	ARS_BUSY,
 	ARS_CANCEL,
+	ARS_VALID,
 	ARS_POLL,
 };
 

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