1 files changed, 75 insertions, 3 deletions

diff --git a/arch/sparc64/kernel/mdesc.c b/arch/sparc64/kernel/mdesc.c
index de5310ffdb48..302ba5e5a0bb 100644
--- a/arch/sparc64/kernel/mdesc.c
+++ b/arch/sparc64/kernel/mdesc.c
@@ -137,7 +137,7 @@ static struct mdesc_handle *mdesc_kmalloc(unsigned int mdesc_size)
                        sizeof(struct mdesc_hdr) +
                        mdesc_size);
 
-        base = kmalloc(handle_size + 15, GFP_KERNEL);
+        base = kmalloc(handle_size + 15, GFP_KERNEL | __GFP_NOFAIL);
         if (base) {
                 struct mdesc_handle *hp;
                 unsigned long addr;
@@ -214,18 +214,83 @@ void mdesc_release(struct mdesc_handle *hp)
 }
 EXPORT_SYMBOL(mdesc_release);
 
+static DEFINE_MUTEX(mdesc_mutex);
+static struct mdesc_notifier_client *client_list;
+
+void mdesc_register_notifier(struct mdesc_notifier_client *client)
+{
+        u64 node;
+
+        mutex_lock(&mdesc_mutex);
+        client->next = client_list;
+        client_list = client;
+
+        mdesc_for_each_node_by_name(cur_mdesc, node, client->node_name)
+                client->add(cur_mdesc, node);
+
+        mutex_unlock(&mdesc_mutex);
+}
+
+/* Run 'func' on nodes which are in A but not in B.  */
+static void invoke_on_missing(const char *name,
+                              struct mdesc_handle *a,
+                              struct mdesc_handle *b,
+                              void (*func)(struct mdesc_handle *, u64))
+{
+        u64 node;
+
+        mdesc_for_each_node_by_name(a, node, name) {
+                const u64 *id = mdesc_get_property(a, node, "id", NULL);
+                int found = 0;
+                u64 fnode;
+
+                mdesc_for_each_node_by_name(b, fnode, name) {
+                        const u64 *fid = mdesc_get_property(b, fnode,
+                                                            "id", NULL);
+
+                        if (*id == *fid) {
+                                found = 1;
+                                break;
+                        }
+                }
+                if (!found)
+                        func(a, node);
+        }
+}
+
+static void notify_one(struct mdesc_notifier_client *p,
+                       struct mdesc_handle *old_hp,
+                       struct mdesc_handle *new_hp)
+{
+        invoke_on_missing(p->node_name, old_hp, new_hp, p->remove);
+        invoke_on_missing(p->node_name, new_hp, old_hp, p->add);
+}
+
+static void mdesc_notify_clients(struct mdesc_handle *old_hp,
+                                 struct mdesc_handle *new_hp)
+{
+        struct mdesc_notifier_client *p = client_list;
+
+        while (p) {
+                notify_one(p, old_hp, new_hp);
+                p = p->next;
+        }
+}
+
 void mdesc_update(void)
 {
         unsigned long len, real_len, status;
         struct mdesc_handle *hp, *orig_hp;
         unsigned long flags;
 
+        mutex_lock(&mdesc_mutex);
+
         (void) sun4v_mach_desc(0UL, 0UL, &len);
 
         hp = mdesc_alloc(len, &kmalloc_mdesc_memops);
         if (!hp) {
                 printk(KERN_ERR "MD: mdesc alloc fails\n");
-                return;
+                goto out;
         }
 
         status = sun4v_mach_desc(__pa(&hp->mdesc), len, &real_len);
@@ -234,18 +299,25 @@ void mdesc_update(void)
                        status);
                 atomic_dec(&hp->refcnt);
                 mdesc_free(hp);
-                return;
+                goto out;
         }
 
         spin_lock_irqsave(&mdesc_lock, flags);
         orig_hp = cur_mdesc;
         cur_mdesc = hp;
+        spin_unlock_irqrestore(&mdesc_lock, flags);
 
+        mdesc_notify_clients(orig_hp, hp);
+
+        spin_lock_irqsave(&mdesc_lock, flags);
         if (atomic_dec_and_test(&orig_hp->refcnt))
                 mdesc_free(orig_hp);
         else
                 list_add(&orig_hp->list, &mdesc_zombie_list);
         spin_unlock_irqrestore(&mdesc_lock, flags);
+
+out:
+        mutex_unlock(&mdesc_mutex);
 }
 
 static struct mdesc_elem *node_block(struct mdesc_hdr *mdesc)