To prevent a module being removed whilst attached to a frontend, and
hence xenbus calling into potentially invalid text, take a reference on
the module before calling the probe() method (dropping it if unsuccessful)
and drop the reference after returning from the remove() method.
NOTE: This allows the ad-hoc reference counting in xen-netback to be
removed. This will be done in a subsequent patch.
Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
v2:
- New in v2
---
drivers/xen/xenbus/xenbus_probe.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 5b471889d723..5a4947690500 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -232,9 +232,11 @@ int xenbus_dev_probe(struct device *_dev)
return err;
}
+ __module_get(drv->driver.owner);
+
err = drv->probe(dev, id);
if (err)
- goto fail;
+ goto fail_put;
err = watch_otherend(dev);
if (err) {
@@ -244,6 +246,8 @@ int xenbus_dev_probe(struct device *_dev)
}
return 0;
+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);
@@ -263,6 +267,8 @@ int xenbus_dev_remove(struct device *_dev)
if (drv->remove)
drv->remove(dev);
+ module_put(drv->driver.owner);
+
free_otherend_details(dev);
xenbus_switch_state(dev, XenbusStateClosed);
--
2.20.1
