[PATCH 2/5] staging: vchiq_arm: Fix possible NPR of keep-alive thread

[Stefan Wahren]

In case vchiq_platform_conn_state_changed() is never called or fails before
driver removal, ka_thread won't be a valid pointer to a task_struct. So
do the necessary checks before calling kthread_stop to avoid a crash.

Fixes: 863a756aaf49 ("staging: vc04_services: vchiq_core: Stop kthreads on vchiq module unload")
Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
---
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index e2e80e90b555..d3b7d1227d7d 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -1422,7 +1422,8 @@ static void vchiq_remove(struct platform_device *pdev)
 	kthread_stop(mgmt->state.slot_handler_thread);

 	arm_state = vchiq_platform_get_arm_state(&mgmt->state);
-	kthread_stop(arm_state->ka_thread);
+	if (!IS_ERR_OR_NULL(arm_state->ka_thread))
+		kthread_stop(arm_state->ka_thread);
 }

 static struct platform_driver vchiq_driver = {
--
2.34.1