nfit: disable userspace initiated ars during scrub
While the nfit driver is issuing address range scrub commands and
reaping the results do not permit an ars_start command issued from
userspace. The scrub thread assumes that all ars completions are for
scrubs initiated by platform firmware at boot, or by the nfit driver.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index 3646501..0def4eb 100644
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -2186,6 +2186,28 @@
return wait_for_completion_interruptible(&flush.cmp);
}
+static int acpi_nfit_clear_to_send(struct nvdimm_bus_descriptor *nd_desc,
+ struct nvdimm *nvdimm, unsigned int cmd)
+{
+ struct acpi_nfit_desc *acpi_desc = to_acpi_nfit_desc(nd_desc);
+
+ if (nvdimm)
+ return 0;
+ if (cmd != ND_CMD_ARS_START)
+ return 0;
+
+ /*
+ * The kernel and userspace may race to initiate a scrub, but
+ * the scrub thread is prepared to lose that initial race. It
+ * just needs guarantees that any ars it initiates are not
+ * interrupted by any intervening start reqeusts from userspace.
+ */
+ if (work_busy(&acpi_desc->work))
+ return -EBUSY;
+
+ return 0;
+}
+
void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev)
{
struct nvdimm_bus_descriptor *nd_desc;
@@ -2197,6 +2219,7 @@
nd_desc->provider_name = "ACPI.NFIT";
nd_desc->ndctl = acpi_nfit_ctl;
nd_desc->flush_probe = acpi_nfit_flush_probe;
+ nd_desc->clear_to_send = acpi_nfit_clear_to_send;
nd_desc->attr_groups = acpi_nfit_attribute_groups;
INIT_LIST_HEAD(&acpi_desc->spa_maps);