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

["Jose E. Marchesi" <jose dot marchesi at oracle dot com>]

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.

gdb:

2014-09-26  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'.

	* probe.h (probe_ops): New hooks `enable_probe' and
	`disable_probe'.

gdb/doc:

2014-09-26  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 |   30 +++++++++++++
 gdb/probe.c         |  123 +++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/probe.h         |   12 +++++
 gdb/stap-probe.c    |    2 +
 6 files changed, 185 insertions(+)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5ec0d85..2f94e05 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,18 @@
 2014-09-26  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'.
+
+	* probe.h (probe_ops): New hooks `enable_probe' and
+	`disable_probe'.
+
+2014-09-26  Jose E. Marchesi  <jose.marchesi@oracle.com>
+
 	* probe.c (compute_probe_arg): Function moved from the probe
 	backends.
 	(compile_probe_arg): Likewise.
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 9a4bc09..5667bf1 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2014-09-26  Jose E. Marchesi  <jose.marchesi@oracle.com>
+
+	* gdb.texinfo (Static Probe Points): Cover the `enable probe' and
+	`disable probe' commands.
+
 2014-09-22  Jan-Benedict Glaw  <jbglaw@lug-owl.de>
 
 	* gdb.texinfo (Set Breaks): Add missing "@end table".
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 026706a..4d6dfbc 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -4976,6 +4976,36 @@ 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 effects
+associated to enabling or disabling a probe depend on the type of
+probe being handled. @code{SystemTap} probes do not support these
+notions.
+
+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,
+probes by 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 d218f00..1e5c460 100644
--- a/gdb/probe.c
+++ b/gdb/probe.c
@@ -685,6 +685,106 @@ 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;
+
+  /* Do we have a `provider:probe:objfile' style of linespec?  */
+  provider = extract_arg (&arg);
+  if (provider)
+    {
+      make_cleanup (xfree, provider);
+
+      probe_name = extract_arg (&arg);
+      if (probe_name)
+	{
+	  make_cleanup (xfree, probe_name);
+
+	  objname = extract_arg (&arg);
+	  if (objname)
+	    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"));
+      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)
+	{
+	  pops->enable_probe (probe->probe);
+	  ui_out_message (current_uiout, 0,
+			  _("Probe %s:%s enabled.\n"),
+			  probe->probe->provider, probe->probe->name);
+	}
+    }
+}
+
+/* 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;
+
+  /* Do we have a `provider:probe:objfile' style of linespec?  */
+  provider = extract_arg (&arg);
+  if (provider)
+    {
+      make_cleanup (xfree, provider);
+
+      probe_name = extract_arg (&arg);
+      if (probe_name)
+	{
+	  make_cleanup (xfree, probe_name);
+
+	  objname = extract_arg (&arg);
+	  if (objname)
+	    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"));
+      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)
+	{
+	  pops->disable_probe (probe->probe);
+	  ui_out_message (current_uiout, 0,
+			  _("Probe %s:%s disabled.\n"),
+			  probe->probe->provider, probe->probe->name);
+	}
+    }  
+}
+
 /* See comments in probe.h.  */
 
 CORE_ADDR
@@ -946,4 +1046,27 @@ _initialize_probe (void)
 	   _("\
 Show information about all type of probes."),
 	   info_probes_cmdlist_get ());
+
+  add_cmd ("probes", no_class, 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 disable\n\
+all defined probes."),
+	   &enablelist);
+
+  add_cmd ("probes", no_class, 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 b4ff0a6..3f27d0d 100644
--- a/gdb/probe.h
+++ b/gdb/probe.h
@@ -132,6 +132,18 @@ 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 17a73fc..c5d0dbb 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -1675,6 +1675,8 @@ static const struct probe_ops stap_probe_ops =
   stap_probe_destroy,
   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