Messages in this thread Patch in this message | | | From | Paul Durrant <> | Subject | [PATCH v2 1/2] xen/xenbus: reference count registered modules | Date | Fri, 29 Nov 2019 13:43:05 +0000 |
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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@suse.com> Signed-off-by: Paul Durrant <pdurrant@amazon.com> --- Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org>
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
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