Re: [PATCH v9 0/4] Uprobes: Support SDT markers having reference count (semaphore)

[Song Liu]

On Mon, Aug 20, 2018 at 9:42 PM, Ravi Bangoria
<ravi.bangoria@xxxxxxxxxxxxx> wrote:
> Hi Song,
>
>> root@virt-test:~# ~/a.out
>> 11
>> semaphore 0
>> semaphore 0
>> semaphore 2      <<<  when the uprobe is enabled
>
> Yes, this happens when multiple vmas points to the same file portion.
> Can you check /proc/`pgrep a.out`/maps.
>
> Logic is simple. If we are going to patch an instruction, increment the
> reference counter. If we are going to unpatch an instruction, decrement
> the reference counter. In this case, we patched instruction twice and
> thus incremented reference counter twice as well.

Yes, this makes sense.

Song

>
> Ravi
>