[PATCH] detaching and threaded linux apps

[PATCH] detaching and threaded linux apps

[Liam Stewart]

thread_db_detach and lin_lwp_detach don't remove their target operation
structures from the target list when a detach on a threaded application
is done. This leads to the failure of the num_lwps == 1 assertion if a
gdb user (for some reason) detaches again before starting/attaching to a
new inferior.

Liam

-- 
Liam Stewart :: Red Hat Canada, Ltd. :: liams@redhat.com

2002-06-03  Liam Stewart  <liams@redhat.com>

	* lin-lwp.c (lin_lwp_detach): Remove target operation structure
	from target stack after detach operations are done.
	* thread-db.c (thread_db_detach): Ditto.

Index: lin-lwp.c
===================================================================
RCS file: /cvs/src/src/gdb/lin-lwp.c,v
retrieving revision 1.34
diff -c -p -r1.34 lin-lwp.c
*** lin-lwp.c	31 Mar 2002 15:10:38 -0000	1.34
--- lin-lwp.c	3 Jun 2002 18:23:54 -0000
*************** lin_lwp_detach (char *args, int from_tty
*** 498,503 ****
--- 498,505 ----
  
    inferior_ptid = pid_to_ptid (GET_PID (inferior_ptid));
    child_ops.to_detach (args, from_tty);
+ 
+   unpush_target(&lin_lwp_ops);
  }
  \f
  
Index: thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/thread-db.c,v
retrieving revision 1.22
diff -c -p -r1.22 thread-db.c
*** thread-db.c	23 Mar 2002 17:38:13 -0000	1.22
--- thread-db.c	3 Jun 2002 18:23:54 -0000
*************** thread_db_detach (char *args, int from_t
*** 627,632 ****
--- 627,634 ----
    proc_handle.pid = 0;
  
    target_beneath->to_detach (args, from_tty);
+ 
+   unpush_target(&thread_db_ops);
  }
  
  static void

Re: [PATCH] detaching and threaded linux apps

[Mark Kettenis]

Liam Stewart <liams@redhat.com> writes:

> thread_db_detach and lin_lwp_detach don't remove their target operation
> structures from the target list when a detach on a threaded application
> is done. This leads to the failure of the num_lwps == 1 assertion if a
> gdb user (for some reason) detaches again before starting/attaching to a
> new inferior.

The fact that thread_db_detach and lin_lwp_detach don't unpush their
targect vector is intentional.  The target vector is installed as a
result of loading the thread library, not (necessarily) as a result of
attaching to a threaded application.  Therefore is should only be
uninstalled if the thread library is unloaded.  The right wat of
fixing this would be to prevent the assertion being triggered if
num_lwps == 0.  Explicitly checking for this condition and displaying
an error message in lin_lwp_detach() might be sufficient.

Mark

Re: [PATCH] detaching and threaded linux apps

[Liam Stewart]

On Mon, Jun 03, 2002 at 11:53:03PM +0200, Mark Kettenis wrote:
> 
> The fact that thread_db_detach and lin_lwp_detach don't unpush their
> targect vector is intentional.  The target vector is installed as a
> result of loading the thread library, not (necessarily) as a result of
> attaching to a threaded application.  Therefore is should only be
> uninstalled if the thread library is unloaded.  The right wat of
> fixing this would be to prevent the assertion being triggered if
> num_lwps == 0.  Explicitly checking for this condition and displaying
> an error message in lin_lwp_detach() might be sufficient.

Ok. I see exactly what's going on now. Returning from lin_lwp_detach
when there are no lwps works as expected. I don't think that displaying
an error message is neccessary - the behaviour of detach remains
consistent.

Liam

-- 
Liam Stewart :: Red Hat Canada, Ltd. :: liams@redhat.com

2002-06-04  Liam Stewart  <liams@redhat.com>

	* lin-lwp.c (lin_lwp_detach): Don't attempt to detach if there
	* are no lwps.


Index: lin-lwp.c
===================================================================
RCS file: /cvs/src/src/gdb/lin-lwp.c,v
retrieving revision 1.34
diff -c -p -r1.34 lin-lwp.c
*** lin-lwp.c	31 Mar 2002 15:10:38 -0000	1.34
--- lin-lwp.c	4 Jun 2002 15:32:03 -0000
*************** detach_callback (struct lwp_info *lp, vo
*** 482,487 ****
--- 482,490 ----
  static void
  lin_lwp_detach (char *args, int from_tty)
  {
+   if (num_lwps == 0)
+     return;
+ 
    iterate_over_lwps (detach_callback, NULL);
  
    /* Only the initial process should be left right now.  */