Re: [PATCH] Delete program spaces directly when removing inferiors

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 15-07-08 11:34 AM, Simon Marchi wrote:
> 
> On 15-07-08 08:05 AM, Pedro Alves wrote:
>> On 09/29/2014 09:33 PM, Simon Marchi wrote:
>>
>>> -void
>>> -delete_inferior (int pid)
>>> -{
>>> -  struct inferior *inf = find_inferior_pid (pid);
>>> -
>>> -  delete_inferior_1 (inf, 0);
>>> -
>>> -  if (print_inferior_events)
>>> -    printf_unfiltered (_("[Inferior %d exited]\n"), pid);
>>> -}
>>> +  /* If this program space is rendered useless, remove it. */
>>> +  if (program_space_empty_p (inf->pspace))
>>> +      delete_program_space (inf->pspace);
>>
>> I think there's something odd with indentation here.
> 
> Ok.
> 
>>> -  struct program_space *ss, **ss_link;
>>> -  struct program_space *current = current_program_space;
>>> +  gdb_assert(pspace != NULL);
>>> +  gdb_assert(pspace != current_program_space);
>>>  
>>> -  ss = program_spaces;
>>> -  ss_link = &program_spaces;
>>> -  while (ss)
>>> +  if (pspace == program_spaces)
>>> +    program_spaces = pspace->next;
>>> +  else
>>>      {
>>> -      if (ss == current || !pspace_empty_p (ss))
>>> +      struct program_space *i = program_spaces;
>>> +
>>> +      for (i = program_spaces; i != NULL; i = i->next)
>>>  	{
>>> -	  ss_link = &ss->next;
>>> -	  ss = *ss_link;
>>> -	  continue;
>>> +	  if (i->next == pspace)
>>> +	    {
>>> +	      i->next = i->next->next;
>>> +	      break;
>>> +	    }
>>>  	}
>>> -
>>> -      *ss_link = ss->next;
>>> -      release_program_space (ss);
>>> -      ss = *ss_link;
>>>      }
>>
>> I don't find this conversion from while to if+else+for an
>> improvement.  You can instead write:
>>
>>   ss = program_spaces;
>>   ss_link = &program_spaces;
>>   while (ss != NULL)
>>     {
>>       if (ss == pspace)
>>         {
>>          *ss_link = ss->next;
>>           break;
>>         }
>>
>>       ss_link = &ss->next;
>>       ss = *ss_link;
>>     }
>>   release_program_space (pspace);
>>
>> We use this _link pattern in several places.
>>
>> OK with that change.
> 
> Ok, pushed with those changes:
> 
> From 0560c645c02eba2828a053039dcfdf676cdd1d00 Mon Sep 17 00:00:00 2001
> From: Simon Marchi <simon.marchi@ericsson.com>
> Date: Mon, 29 Sep 2014 16:33:10 -0400
> Subject: [PATCH] Delete program spaces directly when removing inferiors
> 
> When deleting an inferior, delete the associated program space as well
> if it becomes unused. This replaces the "pruning" approach, with which
> you could forget to call prune_program_spaces (as seen, with the
> -remove-inferior command, see [1]).
> 
> This allows to remove the prune_program_spaces function. At the same
> time, I was able to clean up the delete_inferior* family.
> delete_inferior_silent and delete_inferior were unused, which allowed
> renaming delete_inferior_1 to delete_inferior. Also, since all calls to
> it were with silent=1, I removed that parameter completely.
> 
> I renamed pspace_empty_p to program_space_empty_p. I prefer if the
> "exported" functions have a more explicit and standard name.
> 
> Tested on Ubuntu 14.10.
> 
> This obsoletes my previous patch "Add call to prune_program_spaces in
> mi_cmd_remove_inferior" [1].
> 
> [1] https://sourceware.org/ml/gdb-patches/2014-09/msg00717.html
> 
> gdb/Changelog:
> 
> 	* inferior.c (delete_inferior_1): Rename to ...
> 	(delete_inferior): ..., remove 'silent' parameter, delete
> 	program space when unused and remove call to prune_program_spaces.
> 	Remove the old, unused, delete_inferior.
> 	(delete_inferior_silent): Remove.
> 	(prune_inferiors): Change call from delete_inferior_1 to
> 	delete_inferior and remove 'silent' parameter. Remove call to
> 	prune_program_spaces.
> 	(remove_inferior_command): Idem.
> 	* inferior.h (delete_inferior_1): Rename to...
> 	(delete_inferior): ..., remove 'silent' parameter and remove the
> 	original delete_inferior.
> 	(delete_inferior_silent): Remove.
> 	* mi/mi-main.c (mi_cmd_remove_inferior): Change call from
> 	delete_inferior_1 to delete_inferior and remove 'silent'
> 	parameter.
> 	* progspace.c (prune_program_spaces): Remove.
> 	(pspace_empty_p): Rename to...
> 	(program_space_empty_p): ... and make non-static.
> 	(delete_program_space): New.
> 	* progspace.h (prune_program_spaces): Remove declaration.
> 	(program_space_empty_p): New declaration.
> 	(delete_program_space): New declaration.
> ---
>  gdb/ChangeLog    | 26 ++++++++++++++++++++++++++
>  gdb/inferior.c   | 39 ++++++++-------------------------------
>  gdb/inferior.h   |  9 +--------
>  gdb/mi/mi-main.c |  2 +-
>  gdb/progspace.c  | 27 ++++++++++++++-------------
>  gdb/progspace.h  | 11 +++++++----
>  6 files changed, 57 insertions(+), 57 deletions(-)
> 
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index b565dde..0a0d50a 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,29 @@
> +2015-07-08  Simon Marchi  <simon.marchi@ericsson.com>
> +
> +	* inferior.c (delete_inferior_1): Rename to ...
> +	(delete_inferior): ..., remove 'silent' parameter, delete
> +	program space when unused and remove call to prune_program_spaces.
> +	Remove the old, unused, delete_inferior.
> +	(delete_inferior_silent): Remove.
> +	(prune_inferiors): Change call from delete_inferior_1 to
> +	delete_inferior and remove 'silent' parameter. Remove call to
> +	prune_program_spaces.
> +	(remove_inferior_command): Idem.
> +	* inferior.h (delete_inferior_1): Rename to...
> +	(delete_inferior): ..., remove 'silent' parameter and remove the
> +	original delete_inferior.
> +	(delete_inferior_silent): Remove.
> +	* mi/mi-main.c (mi_cmd_remove_inferior): Change call from
> +	delete_inferior_1 to delete_inferior and remove 'silent'
> +	parameter.
> +	* progspace.c (prune_program_spaces): Remove.
> +	(pspace_empty_p): Rename to...
> +	(program_space_empty_p): ... and make non-static.
> +	(delete_program_space): New.
> +	* progspace.h (prune_program_spaces): Remove declaration.
> +	(program_space_empty_p): New declaration.
> +	(delete_program_space): New declaration.
> +
>  2015-07-08  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
>  	PR compile/18484
> diff --git a/gdb/inferior.c b/gdb/inferior.c
> index d0783d3..5e98df5 100644
> --- a/gdb/inferior.c
> +++ b/gdb/inferior.c
> @@ -184,11 +184,8 @@ delete_thread_of_inferior (struct thread_info *tp, void *data)
>    return 0;
>  }
> 
> -/* If SILENT then be quiet -- don't announce a inferior death, or the
> -   exit of its threads.  */
> -
>  void
> -delete_inferior_1 (struct inferior *todel, int silent)
> +delete_inferior (struct inferior *todel)
>  {
>    struct inferior *inf, *infprev;
>    struct delete_thread_of_inferior_arg arg;
> @@ -203,7 +200,7 @@ delete_inferior_1 (struct inferior *todel, int silent)
>      return;
> 
>    arg.pid = inf->pid;
> -  arg.silent = silent;
> +  arg.silent = 1;
> 
>    iterate_over_threads (delete_thread_of_inferior, &arg);
> 
> @@ -214,29 +211,13 @@ delete_inferior_1 (struct inferior *todel, int silent)
> 
>    observer_notify_inferior_removed (inf);
> 
> -  free_inferior (inf);
> -}
> -
> -void
> -delete_inferior (int pid)
> -{
> -  struct inferior *inf = find_inferior_pid (pid);
> -
> -  delete_inferior_1 (inf, 0);
> -
> -  if (print_inferior_events)
> -    printf_unfiltered (_("[Inferior %d exited]\n"), pid);
> -}
> +  /* If this program space is rendered useless, remove it. */
> +  if (program_space_empty_p (inf->pspace))
> +    delete_program_space (inf->pspace);
> 
> -void
> -delete_inferior_silent (int pid)
> -{
> -  struct inferior *inf = find_inferior_pid (pid);
> -
> -  delete_inferior_1 (inf, 1);
> +  free_inferior (inf);
>  }
> 
> -
>  /* If SILENT then be quiet -- don't announce a inferior exit, or the
>     exit of its threads.  */
> 
> @@ -509,11 +490,9 @@ prune_inferiors (void)
>  	}
> 
>        *ss_link = ss->next;
> -      delete_inferior_1 (ss, 1);
> +      delete_inferior (ss);
>        ss = *ss_link;
>      }
> -
> -  prune_program_spaces ();
>  }
> 
>  /* Simply returns the count of inferiors.  */
> @@ -797,10 +776,8 @@ remove_inferior_command (char *args, int from_tty)
>  	  continue;
>  	}
> 
> -      delete_inferior_1 (inf, 1);
> +      delete_inferior (inf);
>      }
> -
> -  prune_program_spaces ();
>  }
> 
>  struct inferior *
> diff --git a/gdb/inferior.h b/gdb/inferior.h
> index 2054a2a..48cba45 100644
> --- a/gdb/inferior.h
> +++ b/gdb/inferior.h
> @@ -418,14 +418,7 @@ extern struct inferior *add_inferior (int pid);
>     the CLI.  */
>  extern struct inferior *add_inferior_silent (int pid);
> 
> -/* Delete an existing inferior list entry, due to inferior exit.  */
> -extern void delete_inferior (int pid);
> -
> -extern void delete_inferior_1 (struct inferior *todel, int silent);
> -
> -/* Same as delete_inferior, but don't print new inferior notifications
> -   to the CLI.  */
> -extern void delete_inferior_silent (int pid);
> +extern void delete_inferior (struct inferior *todel);
> 
>  /* Delete an existing inferior list entry, due to inferior detaching.  */
>  extern void detach_inferior (int pid);
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index ddfc9d9..66bcd88 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1964,7 +1964,7 @@ mi_cmd_remove_inferior (char *command, char **argv, int argc)
>        set_current_program_space (new_inferior->pspace);
>      }
> 
> -  delete_inferior_1 (inf, 1 /* silent */);
> +  delete_inferior (inf);
>  }
> 
>  
> diff --git a/gdb/progspace.c b/gdb/progspace.c
> index 1c0a254..a8f5ea0 100644
> --- a/gdb/progspace.c
> +++ b/gdb/progspace.c
> @@ -235,8 +235,8 @@ save_current_program_space (void)
> 
>  /* Returns true iff there's no inferior bound to PSPACE.  */
> 
> -static int
> -pspace_empty_p (struct program_space *pspace)
> +int
> +program_space_empty_p (struct program_space *pspace)
>  {
>    if (find_inferior_for_program_space (pspace) != NULL)
>        return 0;
> @@ -244,30 +244,31 @@ pspace_empty_p (struct program_space *pspace)
>    return 1;
>  }
> 
> -/* Prune away automatically added program spaces that aren't required
> -   anymore.  */
> +/* Remove a program space from the program spaces list and release it.  It is
> +   an error to call this function while PSPACE is the current program space. */
> 
>  void
> -prune_program_spaces (void)
> +delete_program_space (struct program_space *pspace)
>  {
>    struct program_space *ss, **ss_link;
> -  struct program_space *current = current_program_space;
> +  gdb_assert(pspace != NULL);
> +  gdb_assert(pspace != current_program_space);
> 
>    ss = program_spaces;
>    ss_link = &program_spaces;
> -  while (ss)
> +  while (ss != NULL)
>      {
> -      if (ss == current || !pspace_empty_p (ss))
> +      if (ss == pspace)
>  	{
> -	  ss_link = &ss->next;
> -	  ss = *ss_link;
> -	  continue;
> +	  *ss_link = ss->next;
> +	  break;
>  	}
> 
> -      *ss_link = ss->next;
> -      release_program_space (ss);
> +      ss_link = &ss->next;
>        ss = *ss_link;
>      }
> +
> +  release_program_space (pspace);
>  }
> 
>  /* Prints the list of program spaces and their details on UIOUT.  If
> diff --git a/gdb/progspace.h b/gdb/progspace.h
> index f960093..48f206e 100644
> --- a/gdb/progspace.h
> +++ b/gdb/progspace.h
> @@ -236,9 +236,16 @@ extern struct program_space *current_program_space;
>     pointer to the new object.  */
>  extern struct program_space *add_program_space (struct address_space *aspace);
> 
> +/* Remove a program space from the program spaces list and release it.  It is
> +   an error to call this function while PSPACE is the current program space. */
> +extern void delete_program_space (struct program_space *pspace);
> +
>  /* Returns the number of program spaces listed.  */
>  extern int number_of_program_spaces (void);
> 
> +/* Returns true iff there's no inferior bound to PSPACE.  */
> +extern int program_space_empty_p (struct program_space *pspace);
> +
>  /* Copies program space SRC to DEST.  Copies the main executable file,
>     and the main symbol file.  Returns DEST.  */
>  extern struct program_space *clone_program_space (struct program_space *dest,
> @@ -289,10 +296,6 @@ extern int address_space_num (struct address_space *aspace);
>     mappings.  */
>  extern void update_address_spaces (void);
> 
> -/* Prune away automatically added program spaces that aren't required
> -   anymore.  */
> -extern void prune_program_spaces (void);
> -
>  /* Reset saved solib data at the start of an solib event.  This lets
>     us properly collect the data when calling solib_add, so it can then
>     later be printed.  */
> 

I have reverted the patch, since it causes a build failure:

http://gdb-build.sergiodj.net/builders/Debian-s390x-native-extended-gdbserver-m64/builds/77

delete_inferior_silent is actually used in monitor.c.  What I don't understand is why
monitor.o doesn't get built when I build gdb locally.  When I type "make monitor.o",
I can see the build error at least.