qed: Fix LL2 race during connection terminate

Stress on qedi/qedr load unload lead to list_del corruption.
This is due to ll2 connection terminate freeing resources without
verifying that no more ll2 processing will occur.

This patch unregisters the ll2 status block before terminating
the connection to assure this race does not occur.

Fixes: 1d6cff4f ("qed: Add iSCSI out of order packet handling")
Signed-off-by: NAriel Elior <Ariel.Elior@cavium.com>
Signed-off-by: NMichal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qed/qed_ll2.c

@@ -829,6 +829,9 @@ static int qed_ll2_lb_rxq_completion(struct qed_hwfn *p_hwfn, void *p_cookie)
 	struct qed_ll2_info *p_ll2_conn = (struct qed_ll2_info *)p_cookie;
 	int rc;
 
+	if (!QED_LL2_RX_REGISTERED(p_ll2_conn))
+		return 0;
+
 	rc = qed_ll2_lb_rxq_handler(p_hwfn, p_ll2_conn);
 	if (rc)
 		return rc;
@@ -849,6 +852,9 @@ static int qed_ll2_lb_txq_completion(struct qed_hwfn *p_hwfn, void *p_cookie)
 	u16 new_idx = 0, num_bds = 0;
 	int rc;
 
+	if (!QED_LL2_TX_REGISTERED(p_ll2_conn))
+		return 0;
+
 	new_idx = le16_to_cpu(*p_tx->p_fw_cons);
 	num_bds = ((s16)new_idx - (s16)p_tx->bds_idx);
 
@@ -1915,17 +1921,25 @@ int qed_ll2_terminate_connection(void *cxt, u8 connection_handle)
 
 	/* Stop Tx & Rx of connection, if needed */
 	if (QED_LL2_TX_REGISTERED(p_ll2_conn)) {
+		p_ll2_conn->tx_queue.b_cb_registred = false;
+		smp_wmb(); /* Make sure this is seen by ll2_lb_rxq_completion */
 		rc = qed_sp_ll2_tx_queue_stop(p_hwfn, p_ll2_conn);
 		if (rc)
 			goto out;
+
 		qed_ll2_txq_flush(p_hwfn, connection_handle);
+		qed_int_unregister_cb(p_hwfn, p_ll2_conn->tx_queue.tx_sb_index);
 	}
 
 	if (QED_LL2_RX_REGISTERED(p_ll2_conn)) {
+		p_ll2_conn->rx_queue.b_cb_registred = false;
+		smp_wmb(); /* Make sure this is seen by ll2_lb_rxq_completion */
 		rc = qed_sp_ll2_rx_queue_stop(p_hwfn, p_ll2_conn);
 		if (rc)
 			goto out;
+
 		qed_ll2_rxq_flush(p_hwfn, connection_handle);
+		qed_int_unregister_cb(p_hwfn, p_ll2_conn->rx_queue.rx_sb_index);
 	}
 
 	if (p_ll2_conn->input.conn_type == QED_LL2_TYPE_OOO)
@@ -1974,16 +1988,6 @@ void qed_ll2_release_connection(void *cxt, u8 connection_handle)
 	if (!p_ll2_conn)
 		return;
 
-	if (QED_LL2_RX_REGISTERED(p_ll2_conn)) {
-		p_ll2_conn->rx_queue.b_cb_registred = false;
-		qed_int_unregister_cb(p_hwfn, p_ll2_conn->rx_queue.rx_sb_index);
-	}
-
-	if (QED_LL2_TX_REGISTERED(p_ll2_conn)) {
-		p_ll2_conn->tx_queue.b_cb_registred = false;
-		qed_int_unregister_cb(p_hwfn, p_ll2_conn->tx_queue.tx_sb_index);
-	}
-
 	kfree(p_ll2_conn->tx_queue.descq_mem);
 	qed_chain_free(p_hwfn->cdev, &p_ll2_conn->tx_queue.txq_chain);