[SPARC64]: Add basic infrastructure for MD add/remove notification.

And add dummy handlers for the VIO device layer.  These will be filled
in with real code after the vdc, vnet, and ds drivers are reworked to
have simpler dependencies on the VIO device tree.

Signed-off-by: David S. Miller <davem@davemloft.net>

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)