RE: Does HEAD support non-stop with 'gdbserver --multi' on Linux?

["Marc Khouzam" <marc.khouzam@ericsson.com>]

 

> -----Original Message-----
> From: Pedro Alves [mailto:pedro@codesourcery.com] 
> Sent: Thursday, April 30, 2009 5:45 PM
> To: Marc Khouzam
> Cc: gdb@sourceware.org
> Subject: Re: Does HEAD support non-stop with 'gdbserver 
> --multi' on Linux?
> 
> On Thursday 30 April 2009 21:18:58, Marc Khouzam wrote:
> 
> > > What exactly are you seeing?  I just run a few non-stop test
> > > (mi-nonstop.exp, mi-nsintrall.exp and ns-nsmoribund.exp tests)
> > > against linux x86-64 gdbserver head, and they passed cleanly for
> > > me, so *something* is working.  :-)
> > 
> > It seems no new thread is listed by GDB.
> 
> Hmmm, that should work.  This looks like another manifestation
> of PR threads/10048.  Does this make a difference?

Yes, this fixed the problem.
My Eclipse is still mis-behaving a bit, but that is probably
my code.  The 'info thread' does show all threads.

Heads up on a breakpoint mis-behavior coming in a separate mail :-)

Thanks!

> 
> -- 
> Pedro Alves
> 
> 2009-04-30  Pedro Alves  <pedro@codesourcery.com>
> 
> 	* linux-low.c (must_set_ptrace_flags): Delete.
> 	(linux_create_inferior): Set 
> `lwp->must_set_ptrace_flags' instead
> 	of the global.
> 	(linux_attach_lwp_1): Don't set PTRACE_SETOPTIONS here.  Set
> 	`lwp->must_set_ptrace_flags' instead.
> 	(linux_wait_for_event_1): Set ptrace options here.
> 	(linux_wait_1): ... not here.
> 
> ---
>  gdb/gdbserver/linux-low.c |   27 ++++++++++++++-------------
>  gdb/gdbserver/linux-low.h |    4 ++++
>  2 files changed, 18 insertions(+), 13 deletions(-)
> 
> Index: src/gdb/gdbserver/linux-low.c
> ===================================================================
> --- src.orig/gdb/gdbserver/linux-low.c	2009-04-12 
> 22:44:01.000000000 +0100
> +++ src/gdb/gdbserver/linux-low.c	2009-04-30 
> 22:38:20.000000000 +0100
> @@ -109,8 +109,6 @@ int stopping_threads;
>  /* FIXME make into a target method?  */
>  int using_threads = 1;
>  
> -static int must_set_ptrace_flags;
> -
>  /* This flag is true iff we've just created or attached to our first
>     inferior but it has not stopped yet.  As soon as it does, we need
>     to call the low target's arch_setup callback.  Doing this only on
> @@ -309,7 +307,7 @@ add_lwp (ptid_t ptid)
>  static int
>  linux_create_inferior (char *program, char **allargs)
>  {
> -  void *new_lwp;
> +  struct lwp_info *new_lwp;
>    int pid;
>    ptid_t ptid;
>  
> @@ -344,7 +342,7 @@ linux_create_inferior (char *program, ch
>    ptid = ptid_build (pid, pid, 0);
>    new_lwp = add_lwp (ptid);
>    add_thread (ptid, new_lwp);
> -  must_set_ptrace_flags = 1;
> +  new_lwp->must_set_ptrace_flags = 1;
>  
>    return pid;
>  }
> @@ -373,10 +371,6 @@ linux_attach_lwp_1 (unsigned long lwpid,
>  	       strerror (errno), errno);
>      }
>  
> -  /* FIXME: This intermittently fails.
> -     We need to wait for SIGSTOP first.  */
> -  ptrace (PTRACE_SETOPTIONS, lwpid, 0, PTRACE_O_TRACECLONE);
> -
>    if (initial)
>      /* NOTE/FIXME: This lwp might have not been the tgid.  */
>      ptid = ptid_build (lwpid, lwpid, 0);
> @@ -392,6 +386,11 @@ linux_attach_lwp_1 (unsigned long lwpid,
>    new_lwp = (struct lwp_info *) add_lwp (ptid);
>    add_thread (ptid, new_lwp);
>  
> +
> +  /* We need to wait for SIGSTOP before being able to make the next
> +     ptrace call on this LWP.  */
> +  new_lwp->must_set_ptrace_flags = 1;
> +
>    /* The next time we wait for this LWP we'll see a SIGSTOP 
> as PTRACE_ATTACH
>       brings it to a halt.
>  
> @@ -986,6 +985,13 @@ linux_wait_for_event_1 (ptid_t ptid, int
>  	  continue;
>  	}
>  
> +      if (event_child->must_set_ptrace_flags)
> +	{
> +	  ptrace (PTRACE_SETOPTIONS, lwpid_of (event_child),
> +		  0, PTRACE_O_TRACECLONE);
> +	  event_child->must_set_ptrace_flags = 0;
> +	}
> +
>        if (WIFSTOPPED (*wstat)
>  	  && WSTOPSIG (*wstat) == SIGSTOP
>  	  && event_child->stop_expected)
> @@ -1248,11 +1254,6 @@ retry:
>  
>    lwp = get_thread_lwp (current_inferior);
>  
> -  if (must_set_ptrace_flags)
> -    {
> -      ptrace (PTRACE_SETOPTIONS, lwpid_of (lwp), 0, 
> PTRACE_O_TRACECLONE);
> -      must_set_ptrace_flags = 0;
> -    }
>    /* If we are waiting for a particular child, and it exited,
>       linux_wait_for_event will return its exit status.  Similarly if
>       the last child exited.  If this is not the last child, however,
> Index: src/gdb/gdbserver/linux-low.h
> ===================================================================
> --- src.orig/gdb/gdbserver/linux-low.h	2009-04-12 
> 22:44:01.000000000 +0100
> +++ src/gdb/gdbserver/linux-low.h	2009-04-30 
> 22:33:09.000000000 +0100
> @@ -146,6 +146,10 @@ struct lwp_info
>       was a single-step.  */
>    int stepping;
>  
> +  /* If this flag is set, we need to set the event request flags the
> +     next time we see this LWP stop.  */
> +  int must_set_ptrace_flags;
> +
>    /* If this is non-zero, it points to a chain of signals 
> which need to
>       be delivered to this process.  */
>    struct pending_signals *pending_signals;
> 
>