IB/rxe: Fix a MR reference leak in check_rkey()

Avoid that calling check_rkey() for mem->state == RXE_MEM_STATE_FREE
triggers an MR reference leak.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Andrew Boyer <andrew.boyer@dell.com>
Cc: Moni Shoua <monis@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_resp.c

@@ -418,7 +418,7 @@ static enum resp_states check_length(struct rxe_qp *qp,
 static enum resp_states check_rkey(struct rxe_qp *qp,
 				   struct rxe_pkt_info *pkt)
 {
-	struct rxe_mem *mem;
+	struct rxe_mem *mem = NULL;
 	u64 va;
 	u32 rkey;
 	u32 resid;
@@ -459,38 +459,38 @@ static enum resp_states check_rkey(struct rxe_qp *qp,
 	mem = lookup_mem(qp->pd, access, rkey, lookup_remote);
 	if (!mem) {
 		state = RESPST_ERR_RKEY_VIOLATION;
-		goto err1;
+		goto err;
 	}
 
 	if (unlikely(mem->state == RXE_MEM_STATE_FREE)) {
 		state = RESPST_ERR_RKEY_VIOLATION;
-		goto err1;
+		goto err;
 	}
 
 	if (mem_check_range(mem, va, resid)) {
 		state = RESPST_ERR_RKEY_VIOLATION;
-		goto err2;
+		goto err;
 	}
 
 	if (pkt->mask & RXE_WRITE_MASK)	 {
 		if (resid > mtu) {
 			if (pktlen != mtu || bth_pad(pkt)) {
 				state = RESPST_ERR_LENGTH;
-				goto err2;
+				goto err;
 			}
 
 			resid = mtu;
 		} else {
 			if (pktlen != resid) {
 				state = RESPST_ERR_LENGTH;
-				goto err2;
+				goto err;
 			}
 			if ((bth_pad(pkt) != (0x3 & (-resid)))) {
 				/* This case may not be exactly that
 				 * but nothing else fits.
 				 */
 				state = RESPST_ERR_LENGTH;
-				goto err2;
+				goto err;
 			}
 		}
 	}
@@ -500,9 +500,9 @@ static enum resp_states check_rkey(struct rxe_qp *qp,
 	qp->resp.mr = mem;
 	return RESPST_EXECUTE;
 
-err2:
-	rxe_drop_ref(mem);
-err1:
+err:
+	if (mem)
+		rxe_drop_ref(mem);
 	return state;
 }