[PATCH 1/3] scsi: pm80xx: Set phy->enable_completion only when we wait for it

[TJ Adams <tadamsjr@google.com>]

From: Igor Pylypiv <ipylypiv@google.com>

pm8001_phy_control() populates the enable_completion pointer with a
stack address, sends a PHY_LINK_RESET / PHY_HARD_RESET, waits 300 ms,
and returns. The problem arises when a phy control response comes late.
After 300 ms the pm8001_phy_control() function returns and the passed
enable_completion stack address is no longer valid. Late phy control
response invokes complete() on a dangling enable_completion pointer
which leads to a kernel crash.

Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
Signed-off-by: Terrence Adams <tadamsjr@google.com>
---
 drivers/scsi/pm8001/pm8001_sas.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
index a5a31dfa4512..ee2da8e49d4c 100644
--- a/drivers/scsi/pm8001/pm8001_sas.c
+++ b/drivers/scsi/pm8001/pm8001_sas.c
@@ -166,7 +166,6 @@ int pm8001_phy_control(struct asd_sas_phy *sas_phy, enum phy_func func,
 	unsigned long flags;
 	pm8001_ha = sas_phy->ha->lldd_ha;
 	phy = &pm8001_ha->phy[phy_id];
-	pm8001_ha->phy[phy_id].enable_completion = &completion;
 
 	if (PM8001_CHIP_DISP->fatal_errors(pm8001_ha)) {
 		/*
@@ -190,6 +189,7 @@ int pm8001_phy_control(struct asd_sas_phy *sas_phy, enum phy_func func,
 				rates->maximum_linkrate;
 		}
 		if (pm8001_ha->phy[phy_id].phy_state ==  PHY_LINK_DISABLE) {
+			pm8001_ha->phy[phy_id].enable_completion = &completion;
 			PM8001_CHIP_DISP->phy_start_req(pm8001_ha, phy_id);
 			wait_for_completion(&completion);
 		}
@@ -198,6 +198,7 @@ int pm8001_phy_control(struct asd_sas_phy *sas_phy, enum phy_func func,
 		break;
 	case PHY_FUNC_HARD_RESET:
 		if (pm8001_ha->phy[phy_id].phy_state == PHY_LINK_DISABLE) {
+			pm8001_ha->phy[phy_id].enable_completion = &completion;
 			PM8001_CHIP_DISP->phy_start_req(pm8001_ha, phy_id);
 			wait_for_completion(&completion);
 		}
@@ -206,6 +207,7 @@ int pm8001_phy_control(struct asd_sas_phy *sas_phy, enum phy_func func,
 		break;
 	case PHY_FUNC_LINK_RESET:
 		if (pm8001_ha->phy[phy_id].phy_state == PHY_LINK_DISABLE) {
+			pm8001_ha->phy[phy_id].enable_completion = &completion;
 			PM8001_CHIP_DISP->phy_start_req(pm8001_ha, phy_id);
 			wait_for_completion(&completion);
 		}
-- 
2.45.2.505.gda0bf45e8d-goog