Commit cce94483 authored by Filipe Manco's avatar Filipe Manco Committed by David S. Miller
Browse files

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: default avatarFilipe Manco <filipe.manco@neclab.eu>
Acked-by: default avatarWei Liu <wei.liu2@citrix.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4253ef8f

drivers/net/xen-netback/xenbus.c

+30 −16
Original line number Diff line number Diff line
@@ -271,6 +271,11 @@ static int netback_probe(struct xenbus_device *dev, 
	be->dev = dev;

	dev_set_drvdata(&dev->dev, be);



	be->state = XenbusStateInitialising;

	err = xenbus_switch_state(dev, XenbusStateInitialising);

	if (err)

		goto fail;



	sg = 1;



	do {
@@ -383,11 +388,6 @@ static int netback_probe(struct xenbus_device *dev, 


	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. */

	err = backend_create_xenvif(be);
@@ -492,18 +492,18 @@ static inline void backend_switch_state(struct backend_info *be, 


/* 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.

 *

 * InitWait -> Connected

 *

 *    ^    \         |

 *    |     \        |

 *    |      \       |

 *    |       \      |

 *    |        \     |

 *    |         \    |

 *    |          V   V

 * Initialising -> InitWait -> Connected

 *          \

 *           \        ^    \         |

 *            \       |     \        |

 *             \      |      \       |

 *              \     |       \      |

 *               \    |        \     |

 *                \   |         \    |

 *                 V  |          V   V

 *

 *                  Closed  <-> Closing

 *
@@ -515,6 +515,20 @@ static void set_backend_state(struct backend_info *be, 
{

	while (be->state != 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:

			switch (state) {

			case XenbusStateInitWait:

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