On Fri, Sep 7, 2018 at 6:38 AM Martijn Coenen <maco@xxxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxxx>
> ---
> v2: made sure reserved fields are aligned, and enforce caller zeroes
> all fields except handle, as suggested by Dan Carpenter.
>
> drivers/android/binder.c | 55 +++++++++++++++++++++++++++++
> include/uapi/linux/android/binder.h | 10 ++++++
> 2 files changed, 65 insertions(+)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index d58763b6b0090..5b25412e15ccf 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -4544,6 +4544,42 @@ static int binder_ioctl_set_ctx_mgr(struct file *filp)
> 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;
Aren't we under-reporting the weak refs here? The "internal weak" refs
are the count of elements in node->refs, so we need to add something
like:
hlist_for_each_entry(ref, &node->refs, node_entry)
info->weak_count++;
> +
> + binder_put_node(node);
> +
> + return 0;
> +}
> +
> static int binder_ioctl_get_node_debug_info(struct binder_proc *proc,
> struct binder_node_debug_info *info)
> {
> @@ -4638,6 +4674,25 @@ 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;
>
> diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h
> index bfaec6903b8bc..b9ba520f7e4bb 100644
> --- a/include/uapi/linux/android/binder.h
> +++ b/include/uapi/linux/android/binder.h
> @@ -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
> --
> 2.19.0.rc2.392.g5ba43deb5a-goog
>
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
