drm/amdkfd: fix circular locking on get_wave_state

get_wave_state acquires the mmap_lock on copy_to_user but so do
mmu_notifiers.  mmu_notifiers allows dqm locking so do get_wave_state
outside the dqm_lock to prevent circular locking.

v2: squash in unused variable removal.

Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
index edb14e4a9f333419a08f14d19bcb55495b8269ab..72bea5278add0f25636d88a84f264f402de912af 100644 (file)
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
@@ -1674,29 +1674,27 @@ static int get_wave_state(struct device_queue_manager *dqm,
                          u32 *save_area_used_size)
 {
        struct mqd_manager *mqd_mgr;
-       int r;
 
        dqm_lock(dqm);
 
-       if (q->properties.type != KFD_QUEUE_TYPE_COMPUTE ||
-           q->properties.is_active || !q->device->cwsr_enabled) {
-               r = -EINVAL;
-               goto dqm_unlock;
-       }
-
        mqd_mgr = dqm->mqd_mgrs[KFD_MQD_TYPE_CP];
 
-       if (!mqd_mgr->get_wave_state) {
-               r = -EINVAL;
-               goto dqm_unlock;
+       if (q->properties.type != KFD_QUEUE_TYPE_COMPUTE ||
+           q->properties.is_active || !q->device->cwsr_enabled ||
+           !mqd_mgr->get_wave_state) {
+               dqm_unlock(dqm);
+               return -EINVAL;
        }
 
-       r = mqd_mgr->get_wave_state(mqd_mgr, q->mqd, ctl_stack,
-                       ctl_stack_used_size, save_area_used_size);
-
-dqm_unlock:
        dqm_unlock(dqm);
-       return r;
+
+       /*
+        * get_wave_state is outside the dqm lock to prevent circular locking
+        * and the queue should be protected against destruction by the process
+        * lock.
+        */
+       return mqd_mgr->get_wave_state(mqd_mgr, q->mqd, ctl_stack,
+                       ctl_stack_used_size, save_area_used_size);
 }
 
 static int process_termination_cpsch(struct device_queue_manager *dqm,