dpctl: Update docs about dump-flows and HW offloading.

Since introduction of dynamic flow API for netdevs, tricky
accesses to uninitialized flow API are no longer possible.
So, ovs-dpctl doesn't support dumping HW offloaded flows now.
Claim this in docs and man pages. Additionally forbidden
'type' argument for 'ovs-dpctl dump-flows'.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Roi Dayan <roid@mellanox.com>

Documentation/faq/design.rst

@@ -73,10 +73,13 @@ Q: Why are there so many different ways to dump flows?
       Linux kernel-based datapath.  In Open vSwitch 1.10 and later,
       ovs-vswitchd merges multiple switches into a single datapath, so it will
       show all the flows on all your kernel-based switches.  This command can
-      occasionally be useful for debugging.
+      occasionally be useful for debugging.  It doesn't dump flows that was
+      offloaded to hardware.
 
     - ``ovs-appctl dpif/dump-flows <br>``, new in Open vSwitch 1.10, dumps
       datapath flows for only the specified bridge, regardless of the type.
+      Supports dumping of HW offloaded flows.  See ovs-vswitchd(8) for
+      details.
 
 Q: How does multicast snooping works with VLANs?
 

lib/dpctl.c

@@ -963,6 +963,13 @@ dpctl_dump_flows(int argc, const char *argv[], struct dpctl_params *dpctl_p)
         if (!strncmp(argv[argc - 1], "filter=", 7) && !filter) {
             filter = xstrdup(argv[--argc] + 7);
         } else if (!strncmp(argv[argc - 1], "type=", 5) && !types_list) {
+            if (!dpctl_p->is_appctl) {
+                dpctl_error(dpctl_p, 0,
+                            "Invalid argument 'type'. "
+                            "Use 'ovs-appctl dpctl/dump-flows' instead.");
+                error = EINVAL;
+                goto out_free;
+            }
             types_list = xstrdup(argv[--argc] + 5);
         }
     }

lib/dpctl.man

@@ -119,6 +119,7 @@ flow. As an example, \fBfilter='tcp,tp_src=100'\fR will match the
 datapath flow containing '\fBtcp(src=80/0xff00,dst=8080/0xff)\fR'.
 .IP
 If \fBtype=\fItype\fR is specified, only displays flows of the specified types.
+This option supported only for \fBovs\-appctl dpctl/dump\-flows\fR.
 \fItype\fR is a comma separated list, which can contain any of the following:
 .
    \fBovs\fR - displays flows handled in the ovs dp
@@ -128,6 +129,7 @@ If \fBtype=\fItype\fR is specified, only displays flows of the specified types.
    \fBall\fR - displays all the types of flows
 .IP
 By default all the types of flows are displayed.
+\fBovs\-dpctl\fR always acts as if the \fBtype\fR was \fIovs\fR.
 .
 .IP "\*(DX\fBadd\-flow\fR [\fIdp\fR] \fIflow actions\fR"
 .TP

vswitchd/vswitch.xml

@@ -208,6 +208,11 @@
           available, Open vSwitch may not be able to offload
           functionality to hardware.
         </p>
+        <p>
+          In order to dump HW offloaded flows use
+          <code>ovs-appctl dpctl/dump-flows</code>, <code>ovs-dpctl</code>
+          doesn't support this functionality. See ovs-vswitchd(8) for details.
+        </p>
       </column>
 
       <column name="other_config" key="tc-policy"