Re: [PATCH V4 3/9] New commands `enable probe' and `disable probe'.

[Sergio Durigan Junior <sergiodj@redhat.com>]

On Monday, February 02 2015, Jose E. Marchesi wrote:

> This patch adds the above-mentioned commands to the generic probe
> abstraction implemented in probe.[ch].  The effects associated to
> enabling or disabling a probe depend on the type of probe being
> handled, and is triggered by invoking two back-end hooks in
> `probe_ops'.
>
> In case some particular probe type does not support the notion of
> enabling and/or disabling, the corresponding fields on `probe_ops' can
> be initialized to NULL.  This is the case of SystemTap probes.

Thanks for the patch.  I see you addressed all the comments that I
made in the previous cycle.  I have no further comments.  OK.

> gdb/ChangeLog:
>
> 2015-02-02  Jose E. Marchesi  <jose.marchesi@oracle.com>
>
> 	* stap-probe.c (stap_probe_ops): Add NULLs in the static
> 	stap_probe_ops for `enable_probe' and `disable_probe'.
> 	* probe.c (enable_probes_command): New function.
> 	(disable_probes_command): Likewise.
> 	(_initialize_probe): Define the cli commands `enable probe' and
> 	`disable probe'.
> 	(parse_probe_linespec): New function.
> 	(info_probes_for_ops): Use parse_probe_linespec.
> 	* probe.h (probe_ops): New hooks `enable_probe' and
> 	`disable_probe'.
>
> gdb/doc/ChangeLog:
>
> 2015-02-02  Jose E. Marchesi  <jose.marchesi@oracle.com>
>
> 	* gdb.texinfo (Static Probe Points): Cover the `enable probe' and
> 	`disable probe' commands.
> ---
>  gdb/ChangeLog       |   13 +++++
>  gdb/doc/ChangeLog   |    5 ++
>  gdb/doc/gdb.texinfo |   29 ++++++++++
>  gdb/probe.c         |  153 +++++++++++++++++++++++++++++++++++++++++++++------
>  gdb/probe.h         |   12 ++++
>  gdb/stap-probe.c    |    2 +
>  6 files changed, 198 insertions(+), 16 deletions(-)
>
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index aee17d3..4ab0bba 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -5011,6 +5011,35 @@ given, all object files are considered.
>  List the available static probes, from all types.
>  @end table
>  
> +@cindex enabling and disabling probes
> +Some probe points can be enabled and/or disabled.  The effect of
> +enabling or disabling a probe depends on the type of probe being
> +handled.  @code{SystemTap} probes cannot be disabled.
> +
> +You can enable (or disable) one or more probes using the following
> +commands, with optional arguments:
> +
> +@table @code
> +@kindex enable probes
> +@item enable probes @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
> +If given, @var{provider} is a regular expression used to match against
> +provider names when selecting which probes to enable.  If omitted,
> +all probes from all providers are enabled.
> +
> +If given, @var{name} is a regular expression to match against probe
> +names when selecting which probes to enable.  If omitted, probe names
> +are not considered when deciding whether to enable them.
> +
> +If given, @var{objfile} is a regular expression used to select which
> +object files (executable or shared libraries) to examine.  If not
> +given, all object files are considered.
> +
> +@kindex disable probes
> +@item disable probes @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
> +See the @code{enable probes} command above for a description of the
> +optional arguments accepted by this command.
> +@end table
> +
>  @vindex $_probe_arg@r{, convenience variable}
>  A probe may specify up to twelve arguments.  These are available at the
>  point at which the probe is defined---that is, when the current PC is
> diff --git a/gdb/probe.c b/gdb/probe.c
> index 98113eb..741c120 100644
> --- a/gdb/probe.c
> +++ b/gdb/probe.c
> @@ -527,6 +527,24 @@ exists_probe_with_pops (VEC (bound_probe_s) *probes,
>    return 0;
>  }
>  
> +/* Helper function that parses a probe linespec of the form [PROVIDER
> +   [PROBE [OBJNAME]]] from the provided string STR.  */
> +
> +static void
> +parse_probe_linespec (const char *str, char **provider,
> +		      char **probe_name, char **objname)
> +{
> +  *probe_name = *objname = NULL;
> +
> +  *provider = extract_arg_const (&str);
> +  if (*provider != NULL)
> +    {
> +      *probe_name = extract_arg_const (&str);
> +      if (*probe_name != NULL)
> +	*objname = extract_arg_const (&str);
> +    }
> +}
> +
>  /* See comment in probe.h.  */
>  
>  void
> @@ -546,22 +564,10 @@ info_probes_for_ops (const char *arg, int from_tty,
>    struct bound_probe *probe;
>    struct gdbarch *gdbarch = get_current_arch ();
>  
> -  /* Do we have a `provider:probe:objfile' style of linespec?  */
> -  provider = extract_arg_const (&arg);
> -  if (provider)
> -    {
> -      make_cleanup (xfree, provider);
> -
> -      probe_name = extract_arg_const (&arg);
> -      if (probe_name)
> -	{
> -	  make_cleanup (xfree, probe_name);
> -
> -	  objname = extract_arg_const (&arg);
> -	  if (objname)
> -	    make_cleanup (xfree, objname);
> -	}
> -    }
> +  parse_probe_linespec (arg, &provider, &probe_name, &objname);
> +  make_cleanup (xfree, provider);
> +  make_cleanup (xfree, probe_name);
> +  make_cleanup (xfree, objname);
>  
>    probes = collect_probes (objname, provider, probe_name, pops);
>    make_cleanup (VEC_cleanup (probe_p), &probes);
> @@ -689,6 +695,98 @@ info_probes_command (char *arg, int from_tty)
>    info_probes_for_ops (arg, from_tty, NULL);
>  }
>  
> +/* Implementation of the `enable probes' command.  */
> +
> +static void
> +enable_probes_command (char *arg, int from_tty)
> +{
> +  char *provider, *probe_name = NULL, *objname = NULL;
> +  struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
> +  VEC (bound_probe_s) *probes;
> +  struct bound_probe *probe;
> +  int i;
> +
> +  parse_probe_linespec ((const char *) arg, &provider, &probe_name, &objname);
> +  make_cleanup (xfree, provider);
> +  make_cleanup (xfree, probe_name);
> +  make_cleanup (xfree, objname);
> +
> +  probes = collect_probes (objname, provider, probe_name, NULL);
> +  if (VEC_empty (bound_probe_s, probes))
> +    {
> +      ui_out_message (current_uiout, 0, _("No probes matched.\n"));
> +      do_cleanups (cleanup);
> +      return;
> +    }
> +
> +  /* Enable the selected probes, provided their backends support the
> +     notion of enabling a probe.  */
> +  for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
> +    {
> +      const struct probe_ops *pops = probe->probe->pops;
> +
> +      if (pops->enable_probe != NULL)
> +	{
> +	  pops->enable_probe (probe->probe);
> +	  ui_out_message (current_uiout, 0,
> +			  _("Probe %s:%s enabled.\n"),
> +			  probe->probe->provider, probe->probe->name);
> +	}
> +      else
> +	ui_out_message (current_uiout, 0,
> +			_("Probe %s:%s cannot be enabled.\n"),
> +			probe->probe->provider, probe->probe->name);
> +    }
> +
> +  do_cleanups (cleanup);
> +}
> +
> +/* Implementation of the `disable probes' command.  */
> +
> +static void
> +disable_probes_command (char *arg, int from_tty)
> +{
> +  char *provider, *probe_name = NULL, *objname = NULL;
> +  struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
> +  VEC (bound_probe_s) *probes;
> +  struct bound_probe *probe;
> +  int i;
> +
> +  parse_probe_linespec ((const char *) arg, &provider, &probe_name, &objname);
> +  make_cleanup (xfree, provider);
> +  make_cleanup (xfree, probe_name);
> +  make_cleanup (xfree, objname);
> +
> +  probes = collect_probes (objname, provider, probe_name, NULL /* pops */);
> +  if (VEC_empty (bound_probe_s, probes))
> +    {
> +      ui_out_message (current_uiout, 0, _("No probes matched.\n"));
> +      do_cleanups (cleanup);
> +      return;
> +    }
> +
> +  /* Disable the selected probes, provided their backends support the
> +     notion of enabling a probe.  */
> +  for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
> +    {
> +      const struct probe_ops *pops = probe->probe->pops;
> +
> +      if (pops->disable_probe != NULL)
> +	{
> +	  pops->disable_probe (probe->probe);
> +	  ui_out_message (current_uiout, 0,
> +			  _("Probe %s:%s disabled.\n"),
> +			  probe->probe->provider, probe->probe->name);
> +	}
> +      else
> +	ui_out_message (current_uiout, 0,
> +			_("Probe %s:%s cannot be disabled.\n"),
> +			probe->probe->provider, probe->probe->name);
> +    }
> +
> +  do_cleanups (cleanup);
> +}
> +
>  /* See comments in probe.h.  */
>  
>  CORE_ADDR
> @@ -950,4 +1048,27 @@ _initialize_probe (void)
>  	   _("\
>  Show information about all type of probes."),
>  	   info_probes_cmdlist_get ());
> +
> +  add_cmd ("probes", class_breakpoint, enable_probes_command, _("\
> +Enable probes.\n\
> +Usage: enable probes [PROVIDER [NAME [OBJECT]]]\n\
> +Each argument is a regular expression, used to select probes.\n\
> +PROVIDER matches probe provider names.\n\
> +NAME matches the probe names.\n\
> +OBJECT matches the executable or shared library name.\n\
> +If you do not specify any argument then the command will enable\n\
> +all defined probes."),
> +	   &enablelist);
> +
> +  add_cmd ("probes", class_breakpoint, disable_probes_command, _("\
> +Disable probes.\n\
> +Usage: disable probes [PROVIDER [NAME [OBJECT]]]\n\
> +Each argument is a regular expression, used to select probes.\n\
> +PROVIDER matches probe provider names.\n\
> +NAME matches the probe names.\n\
> +OBJECT matches the executable or shared library name.\n\
> +If you do not specify any argument then the command will disable\n\
> +all defined probes."),
> +	   &disablelist);
> +
>  }
> diff --git a/gdb/probe.h b/gdb/probe.h
> index 5df1976..e8d5dfe 100644
> --- a/gdb/probe.h
> +++ b/gdb/probe.h
> @@ -138,6 +138,18 @@ struct probe_ops
>  
>      void (*gen_info_probes_table_values) (struct probe *probe,
>  					  VEC (const_char_ptr) **values);
> +
> +    /* Enable a probe.  The semantics of "enabling" a probe depend on
> +       the specific backend and the field can be NULL in case enabling
> +       probes is not supported.  */
> +
> +    void (*enable_probe) (struct probe *probe);
> +
> +    /* Disable a probe.  The semantics of "disabling" a probe depend
> +       on the specific backend and the field can be NULL in case
> +       disabling probes is not supported.  */
> +
> +    void (*disable_probe) (struct probe *probe);
>    };
>  
>  /* Definition of a vector of probe_ops.  */
> diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
> index e898f7e..eaf07b9 100644
> --- a/gdb/stap-probe.c
> +++ b/gdb/stap-probe.c
> @@ -1684,6 +1684,8 @@ static const struct probe_ops stap_probe_ops =
>    stap_type_name,
>    stap_gen_info_probes_table_header,
>    stap_gen_info_probes_table_values,
> +  NULL,  /* enable_probe  */
> +  NULL   /* disable_probe  */
>  };
>  
>  /* Implementation of the `info probes stap' command.  */
> -- 
> 1.7.10.4

-- 
Sergio
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