nfit, address-range-scrub: fix scrub in-progress reporting

commit 78727137fdf49edf9f731bde79d7189067b4047a upstream.

There is a small window whereby ARS scan requests can schedule work that
userspace will miss when polling scrub_show. Hold the init_mutex lock
over calls to report the status to close this potential escape. Also,
make sure that requests to cancel the ARS workqueue are treated as an
idle event.

Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Fixes: 37b137ff8c83 ("nfit, libnvdimm: allow an ARS scrub...")
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 3703254..3874eec 100644 (file)
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -967,8 +967,11 @@ static ssize_t scrub_show(struct device *dev,
        if (nd_desc) {
                struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
 
+               mutex_lock(&acpi_desc->init_mutex);
                rc = sprintf(buf, "%d%s", acpi_desc->scrub_count,
-                               (work_busy(&acpi_desc->work)) ? "+\n" : "\n");
+                               work_busy(&acpi_desc->work)
+                               && !acpi_desc->cancel ? "+\n" : "\n");
+               mutex_unlock(&acpi_desc->init_mutex);
        }
        device_unlock(dev);
        return rc;