[iscsi] Eliminate polling while waiting for window to open

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/net/tcp/iscsi.c b/src/net/tcp/iscsi.c
index 34d06ce3a14896e62c6e04717f17abff9a0e3623..8781559924f704f944d0e6b91b52e368d9d3898f 100644 (file)
--- a/src/net/tcp/iscsi.c
+++ b/src/net/tcp/iscsi.c
@@ -1304,6 +1304,24 @@ static int iscsi_rx_login_response ( struct iscsi_session *iscsi,
  *
  */
 
+/**
+ * Pause TX engine
+ *
+ * @v iscsi            iSCSI session
+ */
+static void iscsi_tx_pause ( struct iscsi_session *iscsi ) {
+       process_del ( &iscsi->process );
+}
+
+/**
+ * Resume TX engine
+ *
+ * @v iscsi            iSCSI session
+ */
+static void iscsi_tx_resume ( struct iscsi_session *iscsi ) {
+       process_add ( &iscsi->process );
+}
+
 /**
  * Start up a new TX PDU
  *
@@ -1324,7 +1342,7 @@ static void iscsi_start_tx ( struct iscsi_session *iscsi ) {
        iscsi->tx_state = ISCSI_TX_BHS;
 
        /* Start transmission process */
-       process_add ( &iscsi->process );
+       iscsi_tx_resume ( iscsi );
 }
 
 /**
@@ -1405,7 +1423,7 @@ static void iscsi_tx_done ( struct iscsi_session *iscsi ) {
        struct iscsi_bhs_common *common = &iscsi->tx_bhs.common;
 
        /* Stop transmission process */
-       process_del ( &iscsi->process );
+       iscsi_tx_pause ( iscsi );
 
        switch ( common->opcode & ISCSI_OPCODE_MASK ) {
        case ISCSI_OPCODE_DATA_OUT:
@@ -1468,7 +1486,10 @@ static void iscsi_tx_step ( struct iscsi_session *iscsi ) {
 
                /* Check for window availability, if needed */
                if ( tx_len && ( xfer_window ( &iscsi->socket ) == 0 ) ) {
-                       /* Cannot transmit at this point; stop processing */
+                       /* Cannot transmit at this point; pause
+                        * processing and wait for window to reopen
+                        */
+                       iscsi_tx_pause ( iscsi );
                        return;
                }
 
@@ -1696,6 +1717,8 @@ static int iscsi_vredirect ( struct iscsi_session *iscsi, int type,
 /** iSCSI socket interface operations */
 static struct interface_operation iscsi_socket_operations[] = {
        INTF_OP ( xfer_deliver, struct iscsi_session *, iscsi_socket_deliver ),
+       INTF_OP ( xfer_window_changed, struct iscsi_session *,
+                 iscsi_tx_resume ),
        INTF_OP ( xfer_vredirect, struct iscsi_session *, iscsi_vredirect ),
        INTF_OP ( intf_close, struct iscsi_session *, iscsi_close ),
 };