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authorDave C Boutcher <sleddog@us.ibm.com>2006-01-12 16:08:27 -0600
committerPaul Mackerras <paulus@samba.org>2006-01-13 21:02:50 +1100
commit088186ded490ced80758200cf8f906ed741df306 (patch)
tree0afbaac2b9843937c63da79dfbd91a60f606c00f /arch
parent898b5395e915210f41223caa30312994d64cba1d (diff)
[PATCH] powerpc: Add/remove/update properties in firmware device tree
Add support for updating and removing device tree properties. Since we hand out pointers to properties with gay abandon, we can't just free the property storage. Instead we move deleted, or the old copy of an updated property, to a "dead properties" list. Also note, its not feasable to kref device tree properties. we call get_property() all over the kernel in a wild variety of contexts. One consequence of this change is that we now take a read_lock(&devtree_lock) when doing get_property(). Signed-off-by: Dave Boutcher <sleddog@us.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/prom.c90
1 files changed, 88 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 02e2115323e..70057b63de2 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -1627,6 +1627,11 @@ static void of_node_release(struct kref *kref)
kfree(prop->value);
kfree(prop);
prop = next;
+
+ if (!prop) {
+ prop = node->deadprops;
+ node->deadprops = NULL;
+ }
}
kfree(node->intrs);
kfree(node->full_name);
@@ -1783,13 +1788,16 @@ unsigned char *get_property(struct device_node *np, const char *name,
{
struct property *pp;
+ read_lock(&devtree_lock);
for (pp = np->properties; pp != 0; pp = pp->next)
if (strcmp(pp->name, name) == 0) {
if (lenp != 0)
*lenp = pp->length;
- return pp->value;
+ break;
}
- return NULL;
+ read_unlock(&devtree_lock);
+
+ return pp ? pp->value : NULL;
}
EXPORT_SYMBOL(get_property);
@@ -1823,4 +1831,82 @@ int prom_add_property(struct device_node* np, struct property* prop)
return 0;
}
+/*
+ * Remove a property from a node. Note that we don't actually
+ * remove it, since we have given out who-knows-how-many pointers
+ * to the data using get-property. Instead we just move the property
+ * to the "dead properties" list, so it won't be found any more.
+ */
+int prom_remove_property(struct device_node *np, struct property *prop)
+{
+ struct property **next;
+ int found = 0;
+
+ write_lock(&devtree_lock);
+ next = &np->properties;
+ while (*next) {
+ if (*next == prop) {
+ /* found the node */
+ *next = prop->next;
+ prop->next = np->deadprops;
+ np->deadprops = prop;
+ found = 1;
+ break;
+ }
+ next = &(*next)->next;
+ }
+ write_unlock(&devtree_lock);
+
+ if (!found)
+ return -ENODEV;
+
+#ifdef CONFIG_PROC_DEVICETREE
+ /* try to remove the proc node as well */
+ if (np->pde)
+ proc_device_tree_remove_prop(np->pde, prop);
+#endif /* CONFIG_PROC_DEVICETREE */
+
+ return 0;
+}
+
+/*
+ * Update a property in a node. Note that we don't actually
+ * remove it, since we have given out who-knows-how-many pointers
+ * to the data using get-property. Instead we just move the property
+ * to the "dead properties" list, and add the new property to the
+ * property list
+ */
+int prom_update_property(struct device_node *np,
+ struct property *newprop,
+ struct property *oldprop)
+{
+ struct property **next;
+ int found = 0;
+
+ write_lock(&devtree_lock);
+ next = &np->properties;
+ while (*next) {
+ if (*next == oldprop) {
+ /* found the node */
+ newprop->next = oldprop->next;
+ *next = newprop;
+ oldprop->next = np->deadprops;
+ np->deadprops = oldprop;
+ found = 1;
+ break;
+ }
+ next = &(*next)->next;
+ }
+ write_unlock(&devtree_lock);
+
+ if (!found)
+ return -ENODEV;
+#ifdef CONFIG_PROC_DEVICETREE
+ /* try to add to proc as well if it was initialized */
+ if (np->pde)
+ proc_device_tree_update_prop(np->pde, newprop, oldprop);
+#endif /* CONFIG_PROC_DEVICETREE */
+
+ return 0;
+}