[lldb-dev] Resuming traced process on Linux and SIGSTOP

[Todd Fiala]

My pleasure.


On Tue, Mar 25, 2014 at 2:46 PM, Andrew MacPherson <andrew.macp at gmail.com>wrote:

> Ok, thanks Todd!
>
>
> On Tue, Mar 25, 2014 at 9:41 PM, Todd Fiala <tfiala at google.com> wrote:
>
>> Hey Andrew, this looks fine.  It also tested out just fine as well.
>>
>>
>> On Tue, Mar 25, 2014 at 12:11 PM, Todd Fiala <tfiala at google.com> wrote:
>>
>>> Sure thing :-)
>>>
>>>
>>> On Tue, Mar 25, 2014 at 12:10 PM, Andrew MacPherson <
>>> andrew.macp at gmail.com> wrote:
>>>
>>>> Great, thanks Todd!
>>>>
>>>>
>>>> On Tue, Mar 25, 2014 at 8:09 PM, Todd Fiala <tfiala at google.com> wrote:
>>>>
>>>>> I just finished clearing out some Linux test errors (I'm now all green
>>>>> on Linux x86_64).  I'll add this to a queue I've got with some changes from
>>>>> Piotr, Ed and you in it now.
>>>>>
>>>>>
>>>>> On Tue, Mar 25, 2014 at 12:08 PM, Andrew MacPherson <
>>>>> andrew.macp at gmail.com> wrote:
>>>>>
>>>>>> Just pinging this again in case anyone has a chance to review the
>>>>>> small Linux detach patch here. Thanks!
>>>>>>
>>>>>>
>>>>>> On Sat, Mar 22, 2014 at 11:05 AM, Andrew MacPherson <
>>>>>> andrew.macp at gmail.com> wrote:
>>>>>>
>>>>>>> I'm attaching a patch here that resolves the issue of a signal being
>>>>>>> delivered to the inferior on detach, let me know if I should start a new
>>>>>>> thread for this but since it's related to what we were discussing I'm
>>>>>>> attaching it here. To reproduce the issue just launch a process, then in a
>>>>>>> new terminal:
>>>>>>>
>>>>>>> sudo lldb -p <pid>
>>>>>>> c
>>>>>>> q
>>>>>>>
>>>>>>> When quitting the inferior receives a SIGSTOP because the process is
>>>>>>> already running when the PTRACE_DETACH is sent. I can't find a clear answer
>>>>>>> on what's supposed to happen here (PTRACE_DETACH sent to running thread)
>>>>>>> but this is the behaviour I'm seeing. The docs do indicate that
>>>>>>> PRACE_DETACH is like PTRACE_CONT and should only be sent to a stopped
>>>>>>> thread.
>>>>>>>
>>>>>>> I also tried to add a unit test for this and the previous patch,
>>>>>>> however I hit http://llvm.org/pr16172. The tests these two patches
>>>>>>> require are similar to the one mentioned in that case and I get the same
>>>>>>> errors in my sample test as when running that one:
>>>>>>>
>>>>>>> attach -p <pid> (ok)
>>>>>>> c (ok)
>>>>>>> detach (error: Detach failed: No such process)
>>>>>>>
>>>>>>> And:
>>>>>>>
>>>>>>> attach -p <pid> (ok)
>>>>>>> c (ok)
>>>>>>> process interrupt (ok)
>>>>>>> c (error: Failed to resume process: Resume request failed - process
>>>>>>> still running..)
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Mar 21, 2014 at 8:37 PM, Ed Maste <emaste at freebsd.org>wrote:
>>>>>>>
>>>>>>>> On 21 March 2014 15:14,  <jingham at apple.com> wrote:
>>>>>>>> > I'm pretty sure we have some test cases that test attach.  If we
>>>>>>>> don't, then it would be great to add one.  If we do, then it would be
>>>>>>>> interesting to see why they didn't fail.  For instance, maybe they just
>>>>>>>> didn't bother to try "continue" after the attach.  Just adding that would
>>>>>>>> be good too.
>>>>>>>>
>>>>>>>> We definitely have some, because they used to fail early on in the
>>>>>>>> FreeBSD porting effort.  I suspect that your suggestion is correct
>>>>>>>> and
>>>>>>>> they just don't do anything but attach and then quit.
>>>>>>>>
>>>>>>>> On a related note, I'm pretty sure we don't have tests for detach.
>>>>>>>> I'll see about extending tests to include that at some point.
>>>>>>>>
>>>>>>>> -Ed
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>  Todd Fiala | Software Engineer |  tfiala at google.com |  650-943-3180
>>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Todd Fiala | Software Engineer |  tfiala at google.com |  650-943-3180
>>>
>>
>>
>>
>> --
>> Todd Fiala | Software Engineer |  tfiala at google.com |  650-943-3180
>>
>
>


-- 
Todd Fiala | Software Engineer | tfiala at google.com | 650-943-3180
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