FROMLIST: ANDROID: binder: Add BINDER_GET_NODE_INFO_FOR_REF ioctl.
This allows the context manager to retrieve information about nodes
that it holds a reference to, such as the current number of
references to those nodes.
Such information can for example be used to determine whether the
servicemanager is the only process holding a reference to a node.
This information can then be passed on to the process holding the
node, which can in turn decide whether it wants to shut down to
reduce resource usage.
Signed-off-by: Martijn Coenen <maco@android.com>
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 9c06e7f..dcd75ed 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -4712,6 +4712,42 @@
return ret;
}
+static int binder_ioctl_get_node_info_for_ref(struct binder_proc *proc,
+ struct binder_node_info_for_ref *info)
+{
+ struct binder_node *node;
+ struct binder_context *context = proc->context;
+ __u32 handle = info->handle;
+
+ if (info->strong_count || info->weak_count || info->reserved1 ||
+ info->reserved2 || info->reserved3) {
+ binder_user_error("%d BINDER_GET_NODE_INFO_FOR_REF: only handle may be non-zero.",
+ proc->pid);
+ return -EINVAL;
+ }
+
+ /* This ioctl may only be used by the context manager */
+ mutex_lock(&context->context_mgr_node_lock);
+ if (!context->binder_context_mgr_node ||
+ context->binder_context_mgr_node->proc != proc) {
+ mutex_unlock(&context->context_mgr_node_lock);
+ return -EPERM;
+ }
+ mutex_unlock(&context->context_mgr_node_lock);
+
+ node = binder_get_node_from_ref(proc, handle, true, NULL);
+ if (!node)
+ return -EINVAL;
+
+ info->strong_count = node->local_strong_refs +
+ node->internal_strong_refs;
+ info->weak_count = node->local_weak_refs;
+
+ binder_put_node(node);
+
+ return 0;
+}
+
static int binder_ioctl_get_node_debug_info(struct binder_proc *proc,
struct binder_node_debug_info *info)
{
@@ -4806,6 +4842,25 @@
}
break;
}
+ case BINDER_GET_NODE_INFO_FOR_REF: {
+ struct binder_node_info_for_ref info;
+
+ if (copy_from_user(&info, ubuf, sizeof(info))) {
+ ret = -EFAULT;
+ goto err;
+ }
+
+ ret = binder_ioctl_get_node_info_for_ref(proc, &info);
+ if (ret < 0)
+ goto err;
+
+ if (copy_to_user(ubuf, &info, sizeof(info))) {
+ ret = -EFAULT;
+ goto err;
+ }
+
+ break;
+ }
case BINDER_GET_NODE_DEBUG_INFO: {
struct binder_node_debug_info info;
diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h
index b4723e3..4a1c285 100644
--- a/include/uapi/linux/android/binder.h
+++ b/include/uapi/linux/android/binder.h
@@ -247,6 +247,15 @@
__u32 has_weak_ref;
};
+struct binder_node_info_for_ref {
+ __u32 handle;
+ __u32 strong_count;
+ __u32 weak_count;
+ __u32 reserved1;
+ __u32 reserved2;
+ __u32 reserved3;
+};
+
#define BINDER_WRITE_READ _IOWR('b', 1, struct binder_write_read)
#define BINDER_SET_IDLE_TIMEOUT _IOW('b', 3, __s64)
#define BINDER_SET_MAX_THREADS _IOW('b', 5, __u32)
@@ -255,6 +264,7 @@
#define BINDER_THREAD_EXIT _IOW('b', 8, __s32)
#define BINDER_VERSION _IOWR('b', 9, struct binder_version)
#define BINDER_GET_NODE_DEBUG_INFO _IOWR('b', 11, struct binder_node_debug_info)
+#define BINDER_GET_NODE_INFO_FOR_REF _IOWR('b', 12, struct binder_node_info_for_ref)
/*
* NOTE: Two special error codes you should check for when calling