Re: [PATCH 2/4] uprobes: Change filter_chain() to iterate ->consumers list

[Srikar Dronamraju <srikar@linux.vnet.ibm.com>]

* Oleg Nesterov <oleg@redhat.com> [2012-11-24 19:02:31]:

> Now that it safe to use ->consumer_rwsem under ->mmap_sem we can
> almost finish the implementation of filter_chain(). It still lacks
> the actual uc->filter(...) call but othewrwise it is ready, just
> it pretends that ->filter() always returns true.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>


Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> ---
>  kernel/events/uprobes.c |   21 +++++++++++++--------
>  1 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 03ffbb5..873c993 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -614,14 +614,19 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
> 
>  static bool filter_chain(struct uprobe *uprobe)
>  {
> -	/*
> -	 * TODO:
> -	 *	for_each_consumer(uc)
> -	 *		if (uc->filter(...))
> -	 *			return true;
> -	 *	return false;
> -	 */
> -	return uprobe->consumers != NULL;
> +	struct uprobe_consumer *uc;
> +	bool ret = false;
> +
> +	down_read(&uprobe->consumer_rwsem);
> +	for (uc = uprobe->consumers; uc; uc = uc->next) {
> +		/* TODO: ret = uc->filter(...) */
> +		ret = true;
> +		if (ret)
> +			break;
> +	}
> +	up_read(&uprobe->consumer_rwsem);
> +
> +	return ret;
>  }
> 
>  static int
> -- 
> 1.5.5.1
>