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 (file)
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -2186,6 +2186,28 @@ static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
        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 @@ void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev)
        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);

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 2508251..228c0e9 100644 (file)
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -490,16 +490,24 @@ void wait_nvdimm_bus_probe_idle(struct device *dev)
 }
 
 /* set_config requires an idle interleave set */
-static int nd_cmd_clear_to_send(struct nvdimm *nvdimm, unsigned int cmd)
+static int nd_cmd_clear_to_send(struct nvdimm_bus *nvdimm_bus,
+               struct nvdimm *nvdimm, unsigned int cmd)
 {
-       struct nvdimm_bus *nvdimm_bus;
+       struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
+
+       /* ask the bus provider if it would like to block this request */
+       if (nd_desc->clear_to_send) {
+               int rc = nd_desc->clear_to_send(nd_desc, nvdimm, cmd);
+
+               if (rc)
+                       return rc;
+       }
 
        if (!nvdimm || cmd != ND_CMD_SET_CONFIG_DATA)
                return 0;
 
-       nvdimm_bus = walk_to_nvdimm_bus(&nvdimm->dev);
+       /* prevent label manipulation while the kernel owns label updates */
        wait_nvdimm_bus_probe_idle(&nvdimm_bus->dev);
-
        if (atomic_read(&nvdimm->busy))
                return -EBUSY;
        return 0;
@@ -609,7 +617,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
        }
 
        nvdimm_bus_lock(&nvdimm_bus->dev);
-       rc = nd_cmd_clear_to_send(nvdimm, cmd);
+       rc = nd_cmd_clear_to_send(nvdimm_bus, nvdimm, cmd);
        if (rc)
                goto out_unlock;
 

diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index 2299f87..833867b 100644 (file)
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -72,6 +72,8 @@ struct nvdimm_bus_descriptor {
        char *provider_name;
        ndctl_fn ndctl;
        int (*flush_probe)(struct nvdimm_bus_descriptor *nd_desc);
+       int (*clear_to_send)(struct nvdimm_bus_descriptor *nd_desc,
+                       struct nvdimm *nvdimm, unsigned int cmd);
 };
 
 struct nd_cmd_desc {