[PATCH 4.18 211/350] libnvdimm: Hold reference on parent while scheduling async init

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Duyck <alexander.h.du...@linux.intel.com>

commit b6eae0f61db27748606cc00dafcfd1e2c032f0a5 upstream.

Unlike asynchronous initialization in the core we have not yet associated
the device with the parent, and as such the device doesn't hold a reference
to the parent.

In order to resolve that we should be holding a reference on the parent
until the asynchronous initialization has completed.

Cc: <sta...@vger.kernel.org>
Fixes: 4d88a97aa9e8 ("libnvdimm: ...base ... infrastructure")
Signed-off-by: Alexander Duyck <alexander.h.du...@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/nvdimm/bus.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -488,6 +488,8 @@ static void nd_async_device_register(voi
                put_device(dev);
        }
        put_device(dev);
+       if (dev->parent)
+               put_device(dev->parent);
 }
 
 static void nd_async_device_unregister(void *d, async_cookie_t cookie)
@@ -507,6 +509,8 @@ void __nd_device_register(struct device
        if (!dev)
                return;
        dev->bus = &nvdimm_bus_type;
+       if (dev->parent)
+               get_device(dev->parent);
        get_device(dev);
        async_schedule_domain(nd_async_device_register, dev,
                        &nd_async_domain);