drm/amd/powerplay: added mutex protection on msg issuing

This could avoid the possible race condition.

Signed-off-by: Evan Quan <[e-mail]>
Reviewed-by: Kenneth Feng <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/powerplay/amd_powerplay.c

···
 	hwmgr->not_vf = !amdgpu_sriov_vf(adev);
 	hwmgr->device = amdgpu_cgs_create_device(adev);
 	mutex_init(&hwmgr->smu_lock);
+	mutex_init(&hwmgr->msg_lock);
 	hwmgr->chip_family = adev->family;
 	hwmgr->chip_id = adev->asic_type;
 	hwmgr->feature_mask = adev->pm.pp_feature;
···
 static void amd_powerplay_destroy(struct amdgpu_device *adev)
 {
 	struct pp_hwmgr *hwmgr = adev->powerplay.pp_handle;
+
+	mutex_destroy(&hwmgr->msg_lock);
 
 	kfree(hwmgr->hardcode_pp_table);
 	hwmgr->hardcode_pp_table = NULL;

drivers/gpu/drm/amd/powerplay/inc/hwmgr.h

···
 	bool pm_en;
 	bool pp_one_vf;
 	struct mutex smu_lock;
+	struct mutex msg_lock;
 
 	uint32_t pp_table_version;
 	void *device;

drivers/gpu/drm/amd/powerplay/smumgr/smumgr.c

···
 	    (resp && !hwmgr->smumgr_funcs->get_argument))
 		return -EINVAL;
 
+	mutex_lock(&hwmgr->msg_lock);
+
 	ret = hwmgr->smumgr_funcs->send_msg_to_smc(hwmgr, msg);
-	if (ret)
+	if (ret) {
+		mutex_unlock(&hwmgr->msg_lock);
 		return ret;
+	}
 
 	if (resp)
 		*resp = hwmgr->smumgr_funcs->get_argument(hwmgr);
+
+	mutex_unlock(&hwmgr->msg_lock);
 
 	return ret;
 }
···
 	    (resp && !hwmgr->smumgr_funcs->get_argument))
 		return -EINVAL;
 
+	mutex_lock(&hwmgr->msg_lock);
+
 	ret = hwmgr->smumgr_funcs->send_msg_to_smc_with_parameter(
 						hwmgr, msg, parameter);
-	if (ret)
+	if (ret) {
+		mutex_unlock(&hwmgr->msg_lock);
 		return ret;
+	}
 
 	if (resp)
 		*resp = hwmgr->smumgr_funcs->get_argument(hwmgr);
+
+	mutex_unlock(&hwmgr->msg_lock);
 
 	return ret;
 }