* [PATCH net v6 0/1] xen-netback: windows frontend compatibility fixes
@ 2013-09-26 11:09 Paul Durrant
2013-09-26 11:09 ` [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way Paul Durrant
0 siblings, 1 reply; 6+ messages in thread
From: Paul Durrant @ 2013-09-26 11:09 UTC (permalink / raw)
To: xen-devel, netdev
The following patches fix a couple more issues found when testing with
Windows frontends.
v6:
- Add a comment concerning the backend state field as suggested by
Ian Campbell
v5:
- Fix typos pointed out by Wei Liu
v4:
- Fix problem with hotplug failure noticed by Wei Liu
v3:
- Collapse both v2 patches into a single patch that introduces a new
function to handle backend state transtions. By doing this we ensure that
we always transition through intermediate states and that we don't attempt
repeated connects or disconnects.
v2:
- Add comment in 2/2 to note that state transitions from Connected to Closed
are incorrect.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way
2013-09-26 11:09 [PATCH net v6 0/1] xen-netback: windows frontend compatibility fixes Paul Durrant
@ 2013-09-26 11:09 ` Paul Durrant
2013-09-26 13:07 ` Ian Campbell
2013-09-26 13:07 ` Ian Campbell
0 siblings, 2 replies; 6+ messages in thread
From: Paul Durrant @ 2013-09-26 11:09 UTC (permalink / raw)
To: xen-devel, netdev; +Cc: Paul Durrant, Ian Campbell, Wei Liu, David Vrabel
When the frontend state changes netback now specifies its desired state to
a new function, set_backend_state(), which transitions through any
necessary intermediate states.
This fixes an issue observed with some old Windows frontend drivers where
they failed to transition through the Closing state and netback would not
behave correctly.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
---
drivers/net/xen-netback/xenbus.c | 148 ++++++++++++++++++++++++++++++--------
1 file changed, 118 insertions(+), 30 deletions(-)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index a53782e..b45bce2 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -24,6 +24,12 @@
struct backend_info {
struct xenbus_device *dev;
struct xenvif *vif;
+
+ /* This is the state that will be reflected in xenstore when any
+ * active hotplug script completes.
+ */
+ enum xenbus_state state;
+
enum xenbus_state frontend_state;
struct xenbus_watch hotplug_status_watch;
u8 have_hotplug_status_watch:1;
@@ -136,6 +142,8 @@ static int netback_probe(struct xenbus_device *dev,
if (err)
goto fail;
+ be->state = XenbusStateInitWait;
+
/* This kicks hotplug scripts, so do it immediately. */
backend_create_xenvif(be);
@@ -208,24 +216,113 @@ static void backend_create_xenvif(struct backend_info *be)
kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
}
-
-static void disconnect_backend(struct xenbus_device *dev)
+static void backend_disconnect(struct backend_info *be)
{
- struct backend_info *be = dev_get_drvdata(&dev->dev);
-
if (be->vif)
xenvif_disconnect(be->vif);
}
-static void destroy_backend(struct xenbus_device *dev)
+static void backend_connect(struct backend_info *be)
{
- struct backend_info *be = dev_get_drvdata(&dev->dev);
+ if (be->vif)
+ connect(be);
+}
- if (be->vif) {
- kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
- xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
- xenvif_free(be->vif);
- be->vif = NULL;
+static inline void backend_switch_state(struct backend_info *be,
+ enum xenbus_state state)
+{
+ struct xenbus_device *dev = be->dev;
+
+ pr_debug("%s -> %s\n", dev->nodename, xenbus_strstate(state));
+ be->state = state;
+
+ /* If we are waiting for a hotplug script then defer the
+ * actual xenbus state change.
+ */
+ if (!be->have_hotplug_status_watch)
+ xenbus_switch_state(dev, state);
+}
+
+/* Handle backend state transitions:
+ *
+ * The backend state starts in InitWait and the following transitions are
+ * allowed.
+ *
+ * InitWait -> Connected
+ *
+ * ^ \ |
+ * | \ |
+ * | \ |
+ * | \ |
+ * | \ |
+ * | \ |
+ * | V V
+ *
+ * Closed <-> Closing
+ *
+ * The state argument specifies the eventual state of the backend and the
+ * function transitions to that state via the shortest path.
+ */
+static void set_backend_state(struct backend_info *be,
+ enum xenbus_state state)
+{
+ while (be->state != state) {
+ switch (be->state) {
+ case XenbusStateClosed:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateConnected:
+ pr_info("%s: prepare for reconnect\n",
+ be->dev->nodename);
+ backend_switch_state(be, XenbusStateInitWait);
+ break;
+ case XenbusStateClosing:
+ backend_switch_state(be, XenbusStateClosing);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ case XenbusStateInitWait:
+ switch (state) {
+ case XenbusStateConnected:
+ backend_connect(be);
+ backend_switch_state(be, XenbusStateConnected);
+ break;
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ backend_switch_state(be, XenbusStateClosing);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ case XenbusStateConnected:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ backend_disconnect(be);
+ backend_switch_state(be, XenbusStateClosing);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ case XenbusStateClosing:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateConnected:
+ case XenbusStateClosed:
+ backend_switch_state(be, XenbusStateClosed);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ default:
+ BUG();
+ }
}
}
@@ -237,40 +334,33 @@ static void frontend_changed(struct xenbus_device *dev,
{
struct backend_info *be = dev_get_drvdata(&dev->dev);
- pr_debug("frontend state %s\n", xenbus_strstate(frontend_state));
+ pr_debug("%s -> %s\n", dev->otherend, xenbus_strstate(frontend_state));
be->frontend_state = frontend_state;
switch (frontend_state) {
case XenbusStateInitialising:
- if (dev->state == XenbusStateClosed) {
- pr_info("%s: prepare for reconnect\n", dev->nodename);
- xenbus_switch_state(dev, XenbusStateInitWait);
- }
+ set_backend_state(be, XenbusStateInitWait);
break;
case XenbusStateInitialised:
break;
case XenbusStateConnected:
- if (dev->state == XenbusStateConnected)
- break;
- if (be->vif)
- connect(be);
+ set_backend_state(be, XenbusStateConnected);
break;
case XenbusStateClosing:
- disconnect_backend(dev);
- xenbus_switch_state(dev, XenbusStateClosing);
+ set_backend_state(be, XenbusStateClosing);
break;
case XenbusStateClosed:
- xenbus_switch_state(dev, XenbusStateClosed);
+ set_backend_state(be, XenbusStateClosed);
if (xenbus_dev_is_online(dev))
break;
- destroy_backend(dev);
/* fall through if not online */
case XenbusStateUnknown:
+ set_backend_state(be, XenbusStateClosed);
device_unregister(&dev->dev);
break;
@@ -363,7 +453,9 @@ static void hotplug_status_changed(struct xenbus_watch *watch,
if (IS_ERR(str))
return;
if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
- xenbus_switch_state(be->dev, XenbusStateConnected);
+ /* Complete any pending state change */
+ xenbus_switch_state(be->dev, be->state);
+
/* Not interested in this watch anymore. */
unregister_hotplug_status_watch(be);
}
@@ -393,12 +485,8 @@ static void connect(struct backend_info *be)
err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
hotplug_status_changed,
"%s/%s", dev->nodename, "hotplug-status");
- if (err) {
- /* Switch now, since we can't do a watch. */
- xenbus_switch_state(dev, XenbusStateConnected);
- } else {
+ if (!err)
be->have_hotplug_status_watch = 1;
- }
netif_wake_queue(be->vif->dev);
}
--
1.7.10.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way
2013-09-26 11:09 ` [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way Paul Durrant
@ 2013-09-26 13:07 ` Ian Campbell
2013-09-26 13:16 ` [Xen-devel] " Ian Campbell
2013-09-26 13:07 ` Ian Campbell
1 sibling, 1 reply; 6+ messages in thread
From: Ian Campbell @ 2013-09-26 13:07 UTC (permalink / raw)
To: Paul Durrant; +Cc: xen-devel, netdev, Wei Liu, David Vrabel
On Thu, 2013-09-26 at 12:09 +0100, Paul Durrant wrote:
> When the frontend state changes netback now specifies its desired state to
> a new function, set_backend_state(), which transitions through any
> necessary intermediate states.
> This fixes an issue observed with some old Windows frontend drivers where
> they failed to transition through the Closing state and netback would not
> behave correctly.
>
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way
2013-09-26 11:09 ` [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way Paul Durrant
2013-09-26 13:07 ` Ian Campbell
@ 2013-09-26 13:07 ` Ian Campbell
2013-09-30 19:14 ` David Miller
1 sibling, 1 reply; 6+ messages in thread
From: Ian Campbell @ 2013-09-26 13:07 UTC (permalink / raw)
To: Paul Durrant; +Cc: xen-devel, netdev, Wei Liu, David Vrabel
On Thu, 2013-09-26 at 12:09 +0100, Paul Durrant wrote:
> When the frontend state changes netback now specifies its desired state to
> a new function, set_backend_state(), which transitions through any
> necessary intermediate states.
> This fixes an issue observed with some old Windows frontend drivers where
> they failed to transition through the Closing state and netback would not
> behave correctly.
>
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Xen-devel] [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way
2013-09-26 13:07 ` Ian Campbell
@ 2013-09-26 13:16 ` Ian Campbell
0 siblings, 0 replies; 6+ messages in thread
From: Ian Campbell @ 2013-09-26 13:16 UTC (permalink / raw)
To: Paul Durrant; +Cc: netdev, Wei Liu, David Vrabel, xen-devel
On Thu, 2013-09-26 at 14:07 +0100, Ian Campbell wrote:
> On Thu, 2013-09-26 at 12:09 +0100, Paul Durrant wrote:
> > When the frontend state changes netback now specifies its desired state to
> > a new function, set_backend_state(), which transitions through any
> > necessary intermediate states.
> > This fixes an issue observed with some old Windows frontend drivers where
> > they failed to transition through the Closing state and netback would not
> > behave correctly.
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Sorry, trimmed my quotes too aggressively and nuked my Ack ;-)
Ian.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way
2013-09-26 13:07 ` Ian Campbell
@ 2013-09-30 19:14 ` David Miller
0 siblings, 0 replies; 6+ messages in thread
From: David Miller @ 2013-09-30 19:14 UTC (permalink / raw)
To: Ian.Campbell; +Cc: paul.durrant, xen-devel, netdev, wei.liu2, david.vrabel
From: Ian Campbell <Ian.Campbell@citrix.com>
Date: Thu, 26 Sep 2013 14:07:33 +0100
> On Thu, 2013-09-26 at 12:09 +0100, Paul Durrant wrote:
>> When the frontend state changes netback now specifies its desired state to
>> a new function, set_backend_state(), which transitions through any
>> necessary intermediate states.
>> This fixes an issue observed with some old Windows frontend drivers where
>> they failed to transition through the Closing state and netback would not
>> behave correctly.
>>
>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-09-26 11:09 [PATCH net v6 0/1] xen-netback: windows frontend compatibility fixes Paul Durrant
2013-09-26 11:09 ` [PATCH net v6 1/1] xen-netback: Handle backend state transitions in a more robust way Paul Durrant
2013-09-26 13:07 ` Ian Campbell
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