lkml.org 
[lkml]   [2018]   [Jul]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore)
> Implement the reference counter logic in core uprobe. User will be
> able to use it from trace_uprobe as well as from kernel module. New
> trace_uprobe definition with reference counter will now be:
>
> <path>:<offset>[(ref_ctr_offset)]
>
> where ref_ctr_offset is an optional field. For kernel module, new
> variant of uprobe_register() has been introduced:
>
> uprobe_register_refctr(inode, offset, ref_ctr_offset, consumer)
>

Sorry for bringing this again, but I would actually think the ref_ctr is
a consumer property. i.e the ref_ctr_offset should be part of
uprobe_consumer.

The advantages of doing that would be
1. Dont need to expose uprobe structure and just update our
uprobe_consumer which is already an exported structure.
- Exporting uprobe structure would expose some of our internal
implementation details, basically reduce the freedom of changing stuff
internally.
- we came up with uprobe_arch for the parts that we wanted to expose
to archs. exposing uprobe and uprobe_arch looks weird.

2. ref_ctr_offset is necessarily a consumer property, its not a uprobe
property at all.

3. We dont need to change/add new uprobe_register functions.

The way I look at it is.

Based on the ref_ctr_offset field in consumer, we update_ref_ctr()
around install_breakpoint/remove_breakpoint.

> +static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm)
> +{
> + struct delayed_uprobe *du;
> +
> + if (delayed_uprobe_check(uprobe, mm))
> + return 0;
> +
> + du = kzalloc(sizeof(*du), GFP_KERNEL);
> + if (!du)
> + return -ENOMEM;
> +
> + du->uprobe = uprobe;
> + du->mm = mm;
> + list_add(&du->list, &delayed_uprobe_list);
> + return 0;
> +}
> +

If I understood the delayed_uprobe stuff, its when we could insert a
breakpoint but the vma that has the ref_ctr_offset is not loaded. Is
that correct?

>
> --
> 2.14.4
>

\
 
 \ /
  Last update: 2018-07-02 18:03    [W:0.248 / U:1.716 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site