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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>
Subject: [PATCH 4.4 049/160] libnvdimm: Hold reference on parent while scheduling async init
Date:   Mon, 19 Nov 2018 17:28:08 +0100
Message-Id: <20181119162636.264023428@linuxfoundation.org>
In-Reply-To: <20181119162630.031306128@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Alexander Duyck <alexander.h.duyck@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: <stable@vger.kernel.org>
Fixes: 4d88a97aa9e8 ("libnvdimm: ...base ... infrastructure")
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -158,6 +158,8 @@ 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)
@@ -175,6 +177,8 @@ static void nd_async_device_unregister(v
 void __nd_device_register(struct device *dev)
 {
 	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);