staging: vc04_services: Fix wrong early return in next_service_by_instance()

If kref_get_unless_zero() fails, we should keep looking for the
next service, since the callers of this function expect that a NULL
return value means there are no more.

Signed-off-by: Marcelo Diop-Gonzalez <marcgonzalez@google.com>
Link: https://lore.kernel.org/r/20200213194001.130110-1-marcgonzalez@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
index d7d7f4d..edcd973 100644 (file)
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
@@ -252,11 +252,15 @@ next_service_by_instance(struct vchiq_state *state,
        struct vchiq_service *service;
 
        rcu_read_lock();
-       service = __next_service_by_instance(state, instance, pidx);
-       if (service && kref_get_unless_zero(&service->ref_count))
-               service = rcu_pointer_handoff(service);
-       else
-               service = NULL;
+       while (1) {
+               service = __next_service_by_instance(state, instance, pidx);
+               if (!service)
+                       break;
+               if (kref_get_unless_zero(&service->ref_count)) {
+                       service = rcu_pointer_handoff(service);
+                       break;
+               }
+       }
        rcu_read_unlock();
        return service;
 }