From 672b7763cb2c723fd6f92a3879cc60d2fb11e56a Mon Sep 17 00:00:00 2001
From: Paul Durrant <pdurrant@amazon.com>
Date: Wed, 11 Dec 2019 15:29:54 +0000
Subject: [PATCH] xenbus: limit when state is forced to closed
If a driver probe() fails then leave the xenstore state alone. There is no
reason to modify it as the failure may be due to transient resource
allocation issues and hence a subsequent probe() may succeed.
If the driver supports re-binding then only force state to closed during
remove() only 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.
NOTE: Re-bind support is indicated by new boolean in struct xenbus_driver,
which defaults to false. Subsequent patches will add support to
some backend drivers.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/xenbus/xenbus_probe.c | 12 ++++++++++--
include/xen/xenbus.h | 1 +
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 5aa29396c9e39e..378486b79f96ae 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -255,7 +255,6 @@ fail_put:
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);
@@ -276,7 +275,16 @@ int xenbus_dev_remove(struct device *_dev)
free_otherend_details(dev);
- xenbus_switch_state(dev, XenbusStateClosed);
+ /*
+ * If the toolstack has forced the device state to closing then set
+ * the state to closed now to allow it to be cleaned up.
+ * Similarly, if the driver does not support re-bind, set the
+ * closed.
+ */
+ if (!drv->allow_rebind ||
+ xenbus_read_driver_state(dev->nodename) == XenbusStateClosing)
+ xenbus_switch_state(dev, XenbusStateClosed);
+
return 0;
}
EXPORT_SYMBOL_GPL(xenbus_dev_remove);
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 869c816d5f8c30..24228a102141e3 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -93,6 +93,7 @@ struct xenbus_device_id
struct xenbus_driver {
const char *name; /* defaults to ids[0].devicetype */
const struct xenbus_device_id *ids;
+ bool allow_rebind; /* avoid setting xenstore closed during remove */
int (*probe)(struct xenbus_device *dev,
const struct xenbus_device_id *id);
void (*otherend_changed)(struct xenbus_device *dev,
--
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