Re: Should this be on the blocker list for the 7.10 release?

[Pedro Alves <palves at redhat dot com>]

On 07/07/2015 07:47 PM, Pedro Alves wrote:

> Hmm, indeed:
> 
> (gdb) info inferiors
>   Num  Description       Executable
>   4    process 8393      /home/pedro/bugs/src/test
>   2    process 8388      /home/pedro/bugs/src/test
> * 1    <null>            /home/pedro/bugs/src/test
> (gdb) info threads
> 
> Calling prune_inferiors() at this point (from a top gdb)
> does not remove them, because they still have inf->pid != 0.
> Sounds like we miss mourning inferiors 2 and 4 somehow?

I think I got it.

Enabling logs (master + previous patch) I see:

...
WL: waitpid Thread 0x7ffff7fc2740 (LWP 9513) received Trace/breakpoint trap (stopped)
WL: Handling extended status 0x03057f
LHEW: Got clone event from LWP 9513, new child is LWP 9579
[New Thread 0x7ffff37b8700 (LWP 9579)]
WL: waitpid Thread 0x7ffff7fc2740 (LWP 9508) received 0 (exited)
WL: Thread 0x7ffff7fc2740 (LWP 9508) exited.
                           ^^^^^^^^
[Thread 0x7ffff7fc2740 (LWP 9508) exited]
WL: waitpid Thread 0x7ffff7fc2740 (LWP 9499) received 0 (exited)
WL: Thread 0x7ffff7fc2740 (LWP 9499) exited.
[Thread 0x7ffff7fc2740 (LWP 9499) exited]
RSRL: resuming stopped-resumed LWP Thread 0x7ffff37b8700 (LWP 9579) at 0x3615ef4ce1: step=0
...
(gdb) info inferiors
  Num  Description       Executable
  5    process 9508      /home/pedro/bugs/src/test
               ^^^^
  4    process 9503      /home/pedro/bugs/src/test
  3    process 9500      /home/pedro/bugs/src/test
  2    process 9499      /home/pedro/bugs/src/test
* 1    <null>            /home/pedro/bugs/src/test
(gdb)
...

Note the "Thread 0x7ffff7fc2740 (LWP 9508) exited." line.
That's this in wait_lwp:

      /* Check if the thread has exited.  */
      if (WIFEXITED (status) || WIFSIGNALED (status))
	{
	  thread_dead = 1;
	  if (debug_linux_nat)
	    fprintf_unfiltered (gdb_stdlog, "WL: %s exited.\n",
				target_pid_to_str (lp->ptid));
	}
    }

This code doesn't understand that an WIFEXITED status
of the last lwp of the process should be reported as
process exit.  Haven't tried to fix it yet.

I haven't tried 7.9, but I'd think it possible to trigger
this issue in all-stop there, because all it takes
is a whole process exiting while gdb is iterating
over lwps, stopping them.

Thanks,
Pedro Alves