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

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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>
This commit is contained in:
Michael Ellerman 2007-06-19 16:08:00 +10:00 committed by Paul Mackerras
parent d3b814bb1e
commit 6a281856c0
2 changed files with 12 additions and 0 deletions
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11
arch/powerpc/kernel/prom.c
View File

@ -1375,8 +1375,17 @@ static void of_node_release(struct kref *kref)
struct device_node *node = kref_to_device_node(kref);
struct property *prop = node->properties;
/* We should never be releasing nodes that haven't been detached. */
if (!of_node_check_flag(node, OF_DETACHED)) {
printk("WARNING: Bad of_node_put() on %s\n", node->full_name);
dump_stack();
kref_init(&node->kref);
return;
}
if (!of_node_check_flag(node, OF_DYNAMIC))
return;
while (prop) {
struct property *next = prop->next;
kfree(prop->name);
@ -1457,6 +1466,8 @@ void of_detach_node(const struct device_node *np)
prevsib->sibling = np->sibling;
}
of_node_set_flag(np, OF_DETACHED);
out_unlock:
write_unlock(&devtree_lock);
}

1
include/asm-powerpc/prom.h
View File

@ -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)
{