2019-12-05 14:02:38

by Paul Durrant

Subject: [PATCH 2/4] xenbus: limit when state is forced to closed

Only force state to closed in the case when the toolstack may need to
clean up. This can be detected by checking whether the state in xenstore
has been set to closing prior to device removal.

Signed-off-by: Paul Durrant <[email protected]>
---
Cc: Boris Ostrovsky <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Stefano Stabellini <[email protected]>
---
drivers/xen/xenbus/xenbus_probe.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index a10311c348b9..c54a53da0106 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -255,7 +255,6 @@ int xenbus_dev_probe(struct device *_dev)
module_put(drv->driver.owner);
fail:
xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
- xenbus_switch_state(dev, XenbusStateClosed);
return err;
}
EXPORT_SYMBOL_GPL(xenbus_dev_probe);
@@ -264,6 +263,7 @@ int xenbus_dev_remove(struct device *_dev)
{
struct xenbus_device *dev = to_xenbus_device(_dev);
struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
+ enum xenbus_state state;

DPRINTK("%s", dev->nodename);

@@ -276,7 +276,14 @@ int xenbus_dev_remove(struct device *_dev)

free_otherend_details(dev);

- xenbus_switch_state(dev, XenbusStateClosed);
+ /*
+ * If the toolstack had force the device state to closing then set
+ * the state to closed now to allow it to be cleaned up.
+ */
+ state = xenbus_read_driver_state(dev->nodename);
+ if (state == XenbusStateClosing)
+ xenbus_switch_state(dev, XenbusStateClosed);
+
return 0;
}
EXPORT_SYMBOL_GPL(xenbus_dev_remove);
--
2.20.1

2019-12-09 12:08:49

by Roger Pau Monne

Subject: Re: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed

On Thu, Dec 05, 2019 at 02:01:21PM +0000, Paul Durrant wrote:
> Only force state to closed in the case when the toolstack may need to
> clean up. This can be detected by checking whether the state in xenstore
> has been set to closing prior to device removal.

I'm not sure I see the point of this, I would expect that a failure to
probe or the removal of the device would leave the xenbus state as
closed, which is consistent with the actual driver state.

Can you explain what's the benefit of leaving a device without a
driver in such unknown state?

Thanks, Roger.