acpi/nfit: queue issuing of ars when an uc error notification comes in

When the ACPI UC error notifier gets called and ARS_REQ bit is set
with the passed in flag, we can receive -EBUSY if ARS_REQ bit is already
set for the nfit_spa->ars_state. When that happens, the ARS request is
dropped. That can potentially cause us to miss the unreported errors that
the on going ARS request does not receive. Add an ARS_REQ_REDO state that
will request short ARS upon ARS completion to grab any errors we missed.
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>

drivers/acpi/nfit/core.c

@@ -2567,6 +2567,11 @@ static void ars_complete(struct acpi_nfit_desc *acpi_desc,
 			test_bit(ARS_SHORT, &nfit_spa->ars_state)
 			? "short" : "long");
 	clear_bit(ARS_SHORT, &nfit_spa->ars_state);
+	if (test_and_clear_bit(ARS_REQ_REDO, &nfit_spa->ars_state)) {
+		set_bit(ARS_SHORT, &nfit_spa->ars_state);
+		set_bit(ARS_REQ, &nfit_spa->ars_state);
+		dev_dbg(dev, "ARS: processing scrub request received while in progress\n");
+	} else
 		set_bit(ARS_DONE, &nfit_spa->ars_state);
 }
 
@@ -3242,9 +3247,10 @@ int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc, unsigned long flags)
 		if (test_bit(ARS_FAILED, &nfit_spa->ars_state))
 			continue;
 
-		if (test_and_set_bit(ARS_REQ, &nfit_spa->ars_state))
+		if (test_and_set_bit(ARS_REQ, &nfit_spa->ars_state)) {
 			busy++;
-		else {
+			set_bit(ARS_REQ_REDO, &nfit_spa->ars_state);
+		} else {
 			if (test_bit(ARS_SHORT, &flags))
 				set_bit(ARS_SHORT, &nfit_spa->ars_state);
 			scheduled++;

drivers/acpi/nfit/nfit.h

@@ -119,6 +119,7 @@ enum nfit_dimm_notifiers {
 
 enum nfit_ars_state {
 	ARS_REQ,
+	ARS_REQ_REDO,
 	ARS_DONE,
 	ARS_SHORT,
 	ARS_FAILED,