| Message ID | 20191129134306.2738-2-pdurrant@amazon.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | allow xen-blkback to be cleanly unloaded | expand |
On 29.11.19 14:43, Paul Durrant wrote: > 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> Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
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@suse.com> > Signed-off-by: Paul Durrant <pdurrant@amazon.com> > > --- 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
> -----Original Message----- > From: Jan Beulich <jbeulich@suse.com> > Sent: 29 November 2019 16:01 > To: Durrant, Paul <pdurrant@amazon.com> > Cc: xen-devel@lists.xenproject.org; linux-block@vger.kernel.org; linux- > kernel@vger.kernel.org; Stefano Stabellini <sstabellini@kernel.org>; Boris > Ostrovsky <boris.ostrovsky@oracle.com>; Juergen Gross <jgross@suse.com> > Subject: Re: [PATCH v2 1/2] xen/xenbus: reference count registered modules > > On 29.11.2019 14:43, Paul Durrant wrote: > > To prevent a module being removed whilst attached to a frontend, and > > Why only frontend? > True. Originally this was only intended for backends, but I guess this should now be 'otherend' or some equivalent form of words. > > 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> > > > > --- 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. > Perhaps, yes. Paul > Jan
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);
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(-)