[POWERPC] Add a warning to help trackdown device_node refcounting bugs

When the refcount for a device node goes to 0, we call the
destructor - of_node_release(). This should only happen if we've
already detached the node from the device tree.

So add a flag OF_DETACHED which tracks detached-ness, and if we
find ourselves in of_node_release() without it set, issue a
warning and don't free the device_node. To avoid warning
continuously reinitialise the kref to a sane value.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-powerpc/prom.h b/include/asm-powerpc/prom.h
index f1006b91bd1a..1632baa17dc6 100644
--- a/include/asm-powerpc/prom.h
+++ b/include/asm-powerpc/prom.h
@@ -99,6 +99,7 @@ extern struct device_node *of_chosen;
 
 /* flag descriptions */
 #define OF_DYNAMIC      1 /* node and properties were allocated via kmalloc */
+#define OF_DETACHED     2 /* node has been detached from the device tree */
 
 static inline int of_node_check_flag(struct device_node *n, unsigned long flag)
 {