scsi_transport_srp: Add rport state diagram

Add a diagram in Documentation/scsi/scsi_transport_srp that
illustrates the rport state transitions.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

2 files changed, 33 insertions, 0 deletions

diff --git a/Documentation/scsi/scsi_transport_srp/Makefile b/Documentation/scsi/scsi_transport_srp/Makefile
new file mode 100644
index 000000000000..5f6b567e955c
--- /dev/null
+++ b/Documentation/scsi/scsi_transport_srp/Makefile
@@ -0,0 +1,7 @@
+all: rport_state_diagram.svg rport_state_diagram.png
+
+rport_state_diagram.svg: rport_state_diagram.dot
+        dot -Tsvg -o $@ $<
+
+rport_state_diagram.png: rport_state_diagram.dot
+        dot -Tpng -o $@ $<
diff --git a/Documentation/scsi/scsi_transport_srp/rport_state_diagram.dot b/Documentation/scsi/scsi_transport_srp/rport_state_diagram.dot
new file mode 100644
index 000000000000..75d610d6411a
--- /dev/null
+++ b/Documentation/scsi/scsi_transport_srp/rport_state_diagram.dot
@@ -0,0 +1,26 @@
+digraph srp_initiator {
+        node [shape = doublecircle]; running lost;
+        node [shape = circle];
+
+        {
+          rank = min;
+          running_rta   [ label = "running;\nreconnect\ntimer\nactive" ];
+        };
+        running         [ label = "running;\nreconnect\ntimer\nstopped" ];
+        blocked;
+        failfast        [ label = "fail I/O\nfast" ];
+        lost;
+
+        running -> running_rta          [ label = "fast_io_fail_tmo = off and\ndev_loss_tmo = off;\nsrp_start_tl_fail_timers()" ];
+        running_rta -> running          [ label = "fast_io_fail_tmo = off and\ndev_loss_tmo = off;\nreconnecting succeeded" ];
+        running -> blocked              [ label = "fast_io_fail_tmo >= 0 or\ndev_loss_tmo >= 0;\nsrp_start_tl_fail_timers()" ];
+        running -> failfast             [ label = "fast_io_fail_tmo = off and\ndev_loss_tmo = off;\nreconnecting failed\n" ];
+        blocked -> failfast             [ label = "fast_io_fail_tmo\nexpired or\nreconnecting\nfailed" ];
+        blocked -> lost                 [ label = "dev_loss_tmo\nexpired or\nsrp_stop_rport_timers()" ];
+        failfast -> lost                [ label = "dev_loss_tmo\nexpired or\nsrp_stop_rport_timers()" ];
+        blocked -> running              [ label = "reconnecting\nsucceeded" ];
+        failfast -> failfast            [ label = "reconnecting\nfailed" ];
+        failfast -> running             [ label = "reconnecting\nsucceeded" ];
+        running -> lost                 [ label = "srp_stop_rport_timers()" ];
+        running_rta -> lost             [ label = "srp_stop_rport_timers()" ];
+}