[lldb-dev] [PATCH] Unexpected group-stop with threading under Linux
tfiala at google.com
Mon Jan 27 09:09:49 PST 2014
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
>> 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.
>>> lldb-dev mailing list
>>> lldb-dev at cs.uiuc.edu
>> 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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