Re: [PING] Re: [PATCH v2 3/3] PR remote/19496, timeout in forking-threads-plus-bkpt

[Don Breazeal <donb@codesourcery.com>]

Ping.
Thanks,
--Don

On 3/3/2016 10:20 AM, Don Breazeal wrote:
> Ping.
> I checked, the patch still applies cleanly to mainline.
> Thanks
> --Don
> 
> On 2/25/2016 9:29 AM, Don Breazeal wrote:
>> Ping
>> Thanks,
>> --Don
>>
>> On 2/10/2016 4:28 PM, Don Breazeal wrote:
>>> On 2/1/2016 12:09 PM, Pedro Alves wrote:
>>>> On 02/01/2016 07:29 PM, Don Breazeal wrote:
>>>>> On 2/1/2016 4:05 AM, Pedro Alves wrote:
>>>>
>>>>> Hi Pedro,
>>> ---snip---
>>>>> A fork event was reported to GDB before GDB knew about the parent thread,
>>>>> followed immediately by a breakpoint event in a different thread.  The
>>>>> parent thread was subsequently added via remote_notice_new_inferior in
>>>>> process_stop_reply, but when the thread was added the thread_info.state
>>>>> was set to THREAD_STOPPED.  The fork event was then handled correctly,
>>>>> but when the fork parent was resumed via a call to keep_going, the state
>>>>> was unchanged.
>>>>
>>>> Since this is non-stop, then it sounds to me like the bug is that the
>>>> thread should have been added in THREAD_RUNNING state.
>>>>
>>>> Consider that infrun may be pulling target events out of the target_ops
>>>> backend into its own event queue, but, not process them immediately.
>>>>
>>>> E.g., infrun may be stopping all threads temporarily for a step-over-breakpoint
>>>> operation for thread A (stop_all_threads).  The waitstatus of all threads
>>>> is thus left pending in the thread structure (save_status), including the
>>>> fork event of thread B.  Right at this point, if the user
>>>> does "info threads", that should show thread B (the fork parent) running,
>>>> not stopped, even if internally, gdb is holding it paused for a little bit.
>>>>
>>>
>>> Hi Pedro,
>>> Here is a new patch that adds the threads with the state set to
>>> THREAD_RUNNING for fork events.
>>> Thanks!
>>> --Don
>>>
>>> This patch addresses a failure in
>>> gdb.threads/forking-threads-plus-breakpoint.exp:
>>>
>>> FAIL: gdb.threads/forking-threads-plus-breakpoint.exp: cond_bp_target=1:
>>> detach_on_fork=on: inferior 1 exited (timeout)
>>>
>>> Cause:
>>> A fork event was reported to GDB before GDB knew about the parent thread,
>>> followed immediately by a breakpoint event in a different thread.  The
>>> parent thread was subsequently added via remote_notice_new_inferior in
>>> process_stop_reply, but when the thread was added the thread_info.state
>>> was set to THREAD_STOPPED.  The fork event was then handled correctly,
>>> but when the fork parent was resumed via a call to keep_going, the state
>>> was unchanged.
>>>
>>> The breakpoint event was then handled, which caused all the non-breakpoint
>>> threads to be stopped.  When the breakpoint thread was resumed, all the
>>> non-breakpoint threads were resumed via infrun.c:restart_threads.  Our old
>>> fork parent wasn't restarted, because it still had thread_info.state set to
>>> THREAD_STOPPED.  Ultimately the program under debug hung waiting for a
>>> pthread_join while the old fork parent was stopped forever by GDB.
>>>
>>> Fix:
>>> Make sure to add the fork parent thread in the THREAD_RUNNING state by
>>> calling remote_notice_new_inferior with RUNNING set to 1 when processing
>>> a fork stop reply.
>>>
>>> Tested on x86_64 Linux and Nios II Linux target with x86 Linux host.
>>>
>>> gdb/ChangeLog:
>>> 2016-02-10  Don Breazeal  <donb@codesourcery.com>
>>>
>>> 	* remote.c (process_stop_reply): Call remote_notice_new_inferior
>>> 	with RUNNING set to 1 when handling fork events.
>>>
>>> ---
>>>  gdb/remote.c | 9 ++++++++-
>>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/gdb/remote.c b/gdb/remote.c
>>> index f09a06e..ab750a7 100644
>>> --- a/gdb/remote.c
>>> +++ b/gdb/remote.c
>>> @@ -6818,7 +6818,14 @@ process_stop_reply (struct stop_reply *stop_reply,
>>>  	  VEC_free (cached_reg_t, stop_reply->regcache);
>>>  	}
>>>  
>>> -      remote_notice_new_inferior (ptid, 0);
>>> +      /* If a fork event arrived before we knew about the parent thread,
>>> +	 make sure to mark it as running when it is created.  */
>>> +      if (status->kind == TARGET_WAITKIND_FORKED
>>> +	  || status->kind == TARGET_WAITKIND_VFORKED)
>>> +	remote_notice_new_inferior (ptid, 1);
>>> +      else
>>> +	remote_notice_new_inferior (ptid, 0);
>>> +
>>>        remote_thr = demand_private_info (ptid);
>>>        remote_thr->core = stop_reply->core;
>>>        remote_thr->stop_reason = stop_reply->stop_reason;
>>>
>>
>