[lldb-dev] [PATCH] Unexpected group-stop with threading under Linux

[Todd Fiala]

Sending        source/Plugins/Process/Linux/ProcessMonitor.cpp
Transmitting file data .
Committed revision 200226.



On Mon, Jan 27, 2014 at 9:06 AM, Todd Fiala <tfiala at google.com> wrote:

> Verified this fixes it.  I'll go ahead and check it in.
>
>
> On Mon, Jan 27, 2014 at 9:00 AM, Todd Fiala <tfiala at google.com> wrote:
>
>> I'm giving this a shot now locally.  The change looks reasonable to me -
>> any ptrace experts disagree?
>>
>> The one bit I'm not entirely sure about is: if assertions are disabled,
>> and for some reason the WSTOPSIG(status) is not SIGSTOP (since we're not
>> explicitly checking before the Resume(wait_pid, SIGSTOP) call), how badly
>> can that gunk things up?  An if check before the Resume call would at least
>> stop the wrong signal from getting sent to the inferior if I'm reading it
>> right.
>>
>>
>> On Mon, Jan 27, 2014 at 2:47 AM, Andrew MacPherson <andrew.macp at gmail.com
>> > wrote:
>>
>>> This patch addresses a bug where in a multi-threaded program a new
>>> signal from the inferior may be received before all group-stop messages
>>> from an earlier signal have been handled. The attached .cpp file exposes
>>> the issue:
>>>
>>>    - clang++ -o thread thread.cpp -lpthread -g -O0
>>>    - lldb ./thread
>>>    - r
>>>    - hit Ctrl-C
>>>    - br set -f thread.cpp -l 11
>>>    - c
>>>    - <hang>
>>>
>>> A breakpoint is usually hit before all the group-stop messages involved
>>> in restarting the process are handled and the internal state then gets out
>>> of sync.
>>>
>>> The attached patch solves the issue and all unit tests pass, I'm not a
>>> ptrace expert though so there may be a more appropriate fix. The group-stop
>>> handling was taken from the existing ProcessMonitor::MonitorCallback.
>>>
>>> Thanks,
>>>
>>> Andrew
>>>
>>>
>>>
>>> _______________________________________________
>>> lldb-dev mailing list
>>> lldb-dev at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
>>>
>>>
>>
>>
>> --
>>  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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20140127/9d1a0c08/attachment.html>