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

[Todd Fiala]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20140325/8296b384/attachment.html>