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From b104afd497502321765c2c1ed3f020b1fe4b400a Mon Sep 17 00:00:00 2001
From: Chris Leech <cleech@redhat.com>
Date: Mon, 29 Feb 2016 14:13:27 -0800
Subject: [PATCH v2 4/9] iscsi_tcp set SO_LINGER to abort connection for error
handling
When requests are being failed it's important to abort the TCP
connection rather than let TCP wait and attempt a graceful shutdown.
That can be accomplished by setting the SO_LINGER socket option with a
linger time of 0 to drop queued data and close the connection with a RST
instead of a FIN.
Signed-off-by: Chris Leech <cleech@redhat.com>
---
usr/io.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/usr/io.c b/usr/io.c
index f552e1e..48b233c 100644
--- a/usr/io.c
+++ b/usr/io.c
@@ -391,9 +391,24 @@ iscsi_io_tcp_poll(iscsi_conn_t *conn, int timeout_ms)
void
iscsi_io_tcp_disconnect(iscsi_conn_t *conn)
{
+ struct linger so_linger = { .l_onoff = 1, .l_linger = 0 };
+
if (conn->socket_fd >= 0) {
log_debug(1, "disconnecting conn %p, fd %d", conn,
conn->socket_fd);
+
+ /* If the state is not IN_LOGOUT, this isn't a clean shutdown
+ * and there's some sort of error handling going on. In that
+ * case, set a 0 SO_LINGER to force an abortive close (RST) and
+ * free whatever is sitting in the TCP transmit queue. This is
+ * done to prevent stale data from being sent should the
+ * network connection be restored before TCP times out.
+ */
+ if (conn->state != ISCSI_CONN_STATE_IN_LOGOUT) {
+ setsockopt(conn->socket_fd, SOL_SOCKET, SO_LINGER,
+ &so_linger, sizeof(so_linger));
+ }
+
close(conn->socket_fd);
conn->socket_fd = -1;
}
--
2.5.5