RDMA/rxe: Disallow MR dereg and invalidate when bound

Check that an MR has no bound MWs before allowing a dereg or invalidate
operation.

Link: https://lore.kernel.org/r/20210608042552.33275-11-rpearsonhpe@gmail.comSigned-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/sw/rxe/rxe_loc.h

@@ -87,6 +87,7 @@ struct rxe_mr *lookup_mr(struct rxe_pd *pd, int access, u32 key,
 int mr_check_range(struct rxe_mr *mr, u64 iova, size_t length);
 int advance_dma_data(struct rxe_dma_info *dma, unsigned int length);
 int rxe_invalidate_mr(struct rxe_qp *qp, u32 rkey);
+int rxe_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata);
 void rxe_mr_cleanup(struct rxe_pool_entry *arg);
 
 /* rxe_mw.c */

drivers/infiniband/sw/rxe/rxe_mr.c

@@ -546,6 +546,13 @@ int rxe_invalidate_mr(struct rxe_qp *qp, u32 rkey)
 		goto err_drop_ref;
 	}
 
+	if (atomic_read(&mr->num_mw) > 0) {
+		pr_warn("%s: Attempt to invalidate an MR while bound to MWs\n",
+			__func__);
+		ret = -EINVAL;
+		goto err_drop_ref;
+	}
+
 	mr->state = RXE_MR_STATE_FREE;
 	ret = 0;
 
@@ -555,6 +562,24 @@ int rxe_invalidate_mr(struct rxe_qp *qp, u32 rkey)
 	return ret;
 }
 
+int rxe_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
+{
+	struct rxe_mr *mr = to_rmr(ibmr);
+
+	if (atomic_read(&mr->num_mw) > 0) {
+		pr_warn("%s: Attempt to deregister an MR while bound to MWs\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	mr->state = RXE_MR_STATE_ZOMBIE;
+	rxe_drop_ref(mr_pd(mr));
+	rxe_drop_index(mr);
+	rxe_drop_ref(mr);
+
+	return 0;
+}
+
 void rxe_mr_cleanup(struct rxe_pool_entry *arg)
 {
 	struct rxe_mr *mr = container_of(arg, typeof(*mr), pelem);

drivers/infiniband/sw/rxe/rxe_verbs.c

@@ -959,17 +959,6 @@ static struct ib_mr *rxe_reg_user_mr(struct ib_pd *ibpd,
 	return ERR_PTR(err);
 }
 
-static int rxe_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
-{
-	struct rxe_mr *mr = to_rmr(ibmr);
-
-	mr->state = RXE_MR_STATE_ZOMBIE;
-	rxe_drop_ref(mr_pd(mr));
-	rxe_drop_index(mr);
-	rxe_drop_ref(mr);
-	return 0;
-}
-
 static struct ib_mr *rxe_alloc_mr(struct ib_pd *ibpd, enum ib_mr_type mr_type,
 				  u32 max_num_sg)
 {