binder: make binder_last_id an atomic

Use an atomic for binder_last_id to avoid locking it
Signed-off-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder.c

@@ -59,7 +59,7 @@ static DEFINE_SPINLOCK(binder_dead_nodes_lock);
 
 static struct dentry *binder_debugfs_dir_entry_root;
 static struct dentry *binder_debugfs_dir_entry_proc;
-static int binder_last_id;
+static atomic_t binder_last_id;
 
 #define BINDER_DEBUG_ENTRY(name) \
 static int binder_##name##_open(struct inode *inode, struct file *file) \
@@ -496,7 +496,7 @@ static struct binder_node *binder_new_node(struct binder_proc *proc,
 	binder_stats_created(BINDER_STAT_NODE);
 	rb_link_node(&node->rb_node, parent, p);
 	rb_insert_color(&node->rb_node, &proc->nodes);
-	node->debug_id = ++binder_last_id;
+	node->debug_id = atomic_inc_return(&binder_last_id);
 	node->proc = proc;
 	node->ptr = ptr;
 	node->cookie = cookie;
@@ -639,7 +639,7 @@ static struct binder_ref *binder_get_ref_for_node(struct binder_proc *proc,
 	if (new_ref == NULL)
 		return NULL;
 	binder_stats_created(BINDER_STAT_REF);
-	new_ref->debug_id = ++binder_last_id;
+	new_ref->debug_id = atomic_inc_return(&binder_last_id);
 	new_ref->proc = proc;
 	new_ref->node = node;
 	rb_link_node(&new_ref->rb_node_node, parent, p);
@@ -1527,7 +1527,7 @@ static void binder_transaction(struct binder_proc *proc,
 	}
 	binder_stats_created(BINDER_STAT_TRANSACTION_COMPLETE);
 
-	t->debug_id = ++binder_last_id;
+	t->debug_id = atomic_inc_return(&binder_last_id);
 	e->debug_id = t->debug_id;
 
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