xen-netback: fix error handling on netback_probe()
In case of error during netback_probe() (e.g. an entry missing on the xenstore) netback_remove() is called on the new device, which will set the device backend state to XenbusStateClosed by calling set_backend_state(). However, the backend state wasn't initialized by netback_probe() at this point, which will cause and invalid transaction and set_backend_state() to BUG(). Initialize the backend state at the beginning of netback_probe() to XenbusStateInitialising, and create two new valid state transitions on set_backend_state(), from XenbusStateInitialising to XenbusStateClosed, and from XenbusStateInitialising to XenbusStateInitWait. Signed-off-by: Filipe Manco <filipe.manco@neclab.eu> Acked-by: Wei Liu <wei.liu2@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -271,6 +271,11 @@ static int netback_probe(struct xenbus_device *dev,
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be->dev = dev;
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dev_set_drvdata(&dev->dev, be);
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be->state = XenbusStateInitialising;
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err = xenbus_switch_state(dev, XenbusStateInitialising);
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if (err)
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goto fail;
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sg = 1;
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do {
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@ -383,11 +388,6 @@ static int netback_probe(struct xenbus_device *dev,
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be->hotplug_script = script;
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err = xenbus_switch_state(dev, XenbusStateInitWait);
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if (err)
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goto fail;
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be->state = XenbusStateInitWait;
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/* This kicks hotplug scripts, so do it immediately. */
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err = backend_create_xenvif(be);
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@ -492,20 +492,20 @@ static inline void backend_switch_state(struct backend_info *be,
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/* Handle backend state transitions:
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*
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* The backend state starts in InitWait and the following transitions are
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* The backend state starts in Initialising and the following transitions are
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* allowed.
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*
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* InitWait -> Connected
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* Initialising -> InitWait -> Connected
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* \
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* \ ^ \ |
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* \ | \ |
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* \ | \ |
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* \ | \ |
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* \ | \ |
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* \ | \ |
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* V | V V
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*
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* ^ \ |
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* | \ |
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* | \ |
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* | \ |
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* | \ |
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* | \ |
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* | V V
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*
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* Closed <-> Closing
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* Closed <-> Closing
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*
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* The state argument specifies the eventual state of the backend and the
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* function transitions to that state via the shortest path.
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@ -515,6 +515,20 @@ static void set_backend_state(struct backend_info *be,
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{
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while (be->state != state) {
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switch (be->state) {
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case XenbusStateInitialising:
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switch (state) {
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case XenbusStateInitWait:
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case XenbusStateConnected:
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case XenbusStateClosing:
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backend_switch_state(be, XenbusStateInitWait);
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break;
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case XenbusStateClosed:
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backend_switch_state(be, XenbusStateClosed);
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break;
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default:
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BUG();
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}
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break;
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case XenbusStateClosed:
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switch (state) {
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case XenbusStateInitWait:
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