libnvdimm: btt_devs: Fix locking in namespace_store

Always take device_lock() before nvdimm_bus_lock() to prevent deadlock.

Cc: <stable@vger.kernel.org>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index 59ad54a..cb47751 100644 (file)
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -128,13 +128,13 @@ static ssize_t namespace_store(struct device *dev,
        struct nd_btt *nd_btt = to_nd_btt(dev);
        ssize_t rc;
 
-       nvdimm_bus_lock(dev);
        device_lock(dev);
+       nvdimm_bus_lock(dev);
        rc = nd_namespace_store(dev, &nd_btt->ndns, buf, len);
        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
-       device_unlock(dev);
        nvdimm_bus_unlock(dev);
+       device_unlock(dev);
 
        return rc;
 }