The root node is not set to NULL when the dtpm root node is
removed. Consequently, it is not possible to create a new root as it
is already set.

Set the root node to NULL when the last node is removed.

Signed-off-by: Daniel Lezcano <redacted>
---
 drivers/powercap/dtpm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/powercap/dtpm.c b/drivers/powercap/dtpm.c
index 5a51cd34a7e8..c2185ec5f887 100644
--- a/drivers/powercap/dtpm.c
+++ b/drivers/powercap/dtpm.c

@@ -207,6 +207,9 @@ int dtpm_release_zone(struct powercap_zone *pcz)
        if (dtpm->ops)
                dtpm->ops->release(dtpm);

+       if (root == dtpm)
+               root = NULL;
+
        kfree(dtpm);

        return 0;
--