Re: [RFA] Checkpoint: wait the defunct process when delete it

[Hui Zhu <teawater@gmail.com>]

On Wed, May 12, 2010 at 08:27, Michael Snyder <msnyder@vmware.com> wrote:
>
> Pedro Alves wrote:
>>
>> On Tuesday 11 May 2010 23:43:04, Michael Snyder wrote:
>>
>>
>>>      old_cleanup = save_inferior_ptid ();
>>>      inferior_ptid = fd->parent_ptid;
>>>
>>> Something like this?  Then the original inferior_ptid will be
>>> restored when you do
>>>
>>>> +  if (call_function_by_hand (waitpid_fn, 3, argv) == 0)
>>>> +    return -1;
>>>
>>>      do_cleanups();
>>>
>>>> +  return 0;
>>>> +}
>>
>> That won't work.  You will hit an assertion somewhere: either because
>> inferior_ptid is not found in the linux-nat.c lwp list, or because
>> inferior_ptid is not found in gdb's thread list.  I believe you'll
>> need to do a full linux_nat_switch_fork and back.
>>
>
> There you go.   ;-)
>

Hello guys,

I am sorry that I didn't complete the new patch yesterday.  Thanks for
your help.

According to your comments. I did following change:

1.  Before kill the ptid, GDB switch to ptid and call
"inferior_call_getppid" to get the ppid of this inferior.  And save it
to ppid.

2.  before call "inferior_call_waitpid" to waitpid the ptid.
Check if ppid is a simple thread.  ppid > 1
Check if ppid is the GDB.  If ppid is GDB, it will auto wait the ptid.
 ppid != getpid ()
Check if ppid is stop.  is_stopped (pptid)

3.  In function inferior_call_waitpid, before call waitpid, swith to ppid.

4.  If inferior_call_waitpid, just give a warning to user.

Please help me review it.

Best regards,
Hui

2010-05-12  Hui Zhu  <teawater@gmail.com>

	* linux-fork.c (gdbthread.h): New include.
	(inferior_call_getppid, inferior_call_waitpid): New function.
	(delete_checkpoint_command): Call inferior_call_getppid
	and inferior_call_waitpid.


---
 linux-fork.c |  105 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 104 insertions(+), 1 deletion(-)

--- a/linux-fork.c
+++ b/linux-fork.c
@@ -29,6 +29,7 @@
 #include "gdb_string.h"
 #include "linux-fork.h"
 #include "linux-nat.h"
+#include "gdbthread.h"

 #include <sys/ptrace.h>
 #include "gdb_wait.h"
@@ -410,12 +411,105 @@ linux_fork_detach (char *args, int from_
     delete_fork (inferior_ptid);
 }

+static int
+inferior_call_getppid (ptid_t ptid)
+{
+  struct objfile *getppid_objf;
+  struct value *getppid_fn = NULL, *ret;
+  struct value *argv[4];
+  struct gdbarch *gdbarch = get_current_arch ();
+  struct fork_info *oldfp, *newfp;
+  int ppid = 1;
+
+  /* Switch to ptid.  */
+  oldfp = find_fork_ptid (inferior_ptid);
+  gdb_assert (oldfp != NULL);
+  newfp = find_fork_ptid (ptid);
+  gdb_assert (oldfp != NULL);
+  fork_save_infrun_state (oldfp, 1);
+  remove_breakpoints ();
+  fork_load_infrun_state (newfp);
+  insert_breakpoints ();
+
+  /* Get the getppid_fn.  */
+  if (lookup_minimal_symbol ("getppid", NULL, NULL) != NULL)
+    getppid_fn = find_function_in_inferior ("getppid", &getppid_objf);
+  if (!getppid_fn && lookup_minimal_symbol ("_getppid", NULL, NULL) != NULL)
+    getppid_fn = find_function_in_inferior ("_getppid", &getppid_objf);
+  if (!getppid_fn)
+    return 1;
+
+  ret = call_function_by_hand (getppid_fn, 0, NULL);
+  if (ret == 0)
+    return ppid;
+  ppid = value_as_long (ret);
+
+  /* Switch back to inferior_ptid. */
+  remove_breakpoints ();
+  fork_load_infrun_state (oldfp);
+  insert_breakpoints ();
+
+  return ppid;
+}
+
+static int
+inferior_call_waitpid (ptid_t pptid, int pid)
+{
+  struct objfile *waitpid_objf;
+  struct value *waitpid_fn = NULL;
+  struct value *argv[4];
+  struct gdbarch *gdbarch = get_current_arch ();
+  struct fork_info *oldfp = NULL, *newfp = NULL;
+  int ret = 0;
+
+  if (!ptid_equal (pptid, inferior_ptid))
+    {
+      /* Switch to pptid.  */
+      oldfp = find_fork_ptid (inferior_ptid);
+      gdb_assert (oldfp != NULL);
+      newfp = find_fork_ptid (pptid);
+      gdb_assert (oldfp != NULL);
+      fork_save_infrun_state (oldfp, 1);
+      remove_breakpoints ();
+      fork_load_infrun_state (newfp);
+      insert_breakpoints ();
+    }
+
+  /* Get the waitpid_fn.  */
+  if (lookup_minimal_symbol ("waitpid", NULL, NULL) != NULL)
+    waitpid_fn = find_function_in_inferior ("waitpid", &waitpid_objf);
+  if (!waitpid_fn && lookup_minimal_symbol ("_waitpid", NULL, NULL) != NULL)
+    waitpid_fn = find_function_in_inferior ("_waitpid", &waitpid_objf);
+  if (!waitpid_fn)
+    return -1;
+
+  /* Get the argv.  */
+  argv[0] = value_from_longest (builtin_type (gdbarch)->builtin_int, pid);
+  argv[1] = value_from_longest (builtin_type (gdbarch)->builtin_data_ptr, 0);
+  argv[2] = value_from_longest (builtin_type (gdbarch)->builtin_int, 0);
+  argv[3] = 0;
+
+  if (call_function_by_hand (waitpid_fn, 3, argv) == 0)
+    ret = -1;
+
+  if (oldfp)
+    {
+      /* Switch back to inferior_ptid. */
+      remove_breakpoints ();
+      fork_load_infrun_state (oldfp);
+      insert_breakpoints ();
+    }
+
+  return ret;
+}
+
 /* Fork list <-> user interface.  */

 static void
 delete_checkpoint_command (char *args, int from_tty)
 {
-  ptid_t ptid;
+  ptid_t ptid, pptid;
+  int ppid;

   if (!args || !*args)
     error (_("Requires argument (checkpoint id to delete)"));
@@ -428,9 +522,18 @@ delete_checkpoint_command (char *args, i
     error (_("\
 Please switch to another checkpoint before deleting the current one"));

+  ppid = inferior_call_getppid (ptid);
+  pptid = ptid_build (ppid, ppid, 0);
+
   if (ptrace (PTRACE_KILL, PIDGET (ptid), 0, 0))
     error (_("Unable to kill pid %s"), target_pid_to_str (ptid));

+  if (ppid > 1 && ppid != getpid () && is_stopped (pptid))
+    {
+      if (inferior_call_waitpid (pptid, PIDGET (ptid)))
+        warning (_("Unable to wait pid %s"), target_pid_to_str (ptid));
+    }
+
   if (from_tty)
     printf_filtered (_("Killed %s\n"), target_pid_to_str (ptid));