Commit b7e6a896 authored by Martijn Coenen's avatar Martijn Coenen Committed by Greg Kroah-Hartman
Browse files

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: default avatarMartijn Coenen <maco@android.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6b6642da

drivers/android/binder.c

+55 −0
Original line number Diff line number Diff line
@@ -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;

include/uapi/linux/android/binder.h

+10 −0
Original line number Diff line number Diff line
@@ -200,6 +200,15 @@ struct binder_node_debug_info { 
	__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)
@@ -208,6 +217,7 @@ struct binder_node_debug_info { 
#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

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