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xen-netback: fix error handling on netback_probe()

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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>
This commit is contained in:
Filipe Manco 2016-09-15 17:10:46 +02:00 committed by David S. Miller
parent 4253ef8f6f
commit cce94483e4
1 changed files with 30 additions and 16 deletions
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46
drivers/net/xen-netback/xenbus.c
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@ -271,6 +271,11 @@ static int netback_probe(struct xenbus_device *dev,
be->dev = dev; be->dev = dev;
dev_set_drvdata(&dev->dev, be); dev_set_drvdata(&dev->dev, be);
be->state = XenbusStateInitialising;
err = xenbus_switch_state(dev, XenbusStateInitialising);
if (err)
goto fail;
sg = 1; sg = 1;
do { do {
@ -383,11 +388,6 @@ static int netback_probe(struct xenbus_device *dev,
be->hotplug_script = script; be->hotplug_script = script;
err = xenbus_switch_state(dev, XenbusStateInitWait);
if (err)
goto fail;
be->state = XenbusStateInitWait;
/* This kicks hotplug scripts, so do it immediately. */ /* This kicks hotplug scripts, so do it immediately. */
err = backend_create_xenvif(be); err = backend_create_xenvif(be);
@ -492,20 +492,20 @@ static inline void backend_switch_state(struct backend_info *be,
/* Handle backend state transitions: /* Handle backend state transitions:
* *
* The backend state starts in InitWait and the following transitions are * The backend state starts in Initialising and the following transitions are
* allowed. * allowed.
* *
* InitWait -> Connected * Initialising -> InitWait -> Connected
* \
* \ ^ \ |
* \ | \ |
* \ | \ |
* \ | \ |
* \ | \ |
* \ | \ |
* V | V V
* *
* ^ \ | * Closed <-> Closing
* | \ |
* | \ |
* | \ |
* | \ |
* | \ |
* | V V
*
* Closed <-> Closing
* *
* The state argument specifies the eventual state of the backend and the * The state argument specifies the eventual state of the backend and the
* function transitions to that state via the shortest path. * function transitions to that state via the shortest path.
@ -515,6 +515,20 @@ static void set_backend_state(struct backend_info *be,
{ {
while (be->state != state) { while (be->state != state) {
switch (be->state) { switch (be->state) {
case XenbusStateInitialising:
switch (state) {
case XenbusStateInitWait:
case XenbusStateConnected:
case XenbusStateClosing:
backend_switch_state(be, XenbusStateInitWait);
break;
case XenbusStateClosed:
backend_switch_state(be, XenbusStateClosed);
break;
default:
BUG();
}
break;
case XenbusStateClosed: case XenbusStateClosed:
switch (state) { switch (state) {
case XenbusStateInitWait: case XenbusStateInitWait: