From b7e6a8961b5d6dd3fc535970e65d497d868bb49f Mon Sep 17 00:00:00 2001 From: Martijn Coenen Date: Fri, 7 Sep 2018 15:38:37 +0200 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 46dad7d724ac..1b54bb57a9fb 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -4661,6 +4661,42 @@ out: 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) { @@ -4755,6 +4791,25 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) } 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; -- cgit v1.2.3