ERDMA_RES_TYPE_PD
dev->res_cb[ERDMA_RES_TYPE_PD].max_cap = ERDMA_MAX_PD;
pdn = erdma_alloc_idx(&dev->res_cb[ERDMA_RES_TYPE_PD]);
erdma_free_idx(&dev->res_cb[ERDMA_RES_TYPE_PD], pd->pdn);