Re: [Xen-devel] [PATCH v2 1/2] xen/xenbus: reference count registered modules

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.11.2019 14:43, Paul Durrant wrote:
> To prevent a module being removed whilst attached to a frontend, and

Why only frontend?

> 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>
> 
> --- 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);

I guess you really want try_module_get() and deal with it returning
false.

Jan

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