[PATCH] perf: change event inheritance logic in stat and record

[Stephane Eranian <eranian@google.com>]

  By default, event inheritance across fork and pthread_create was
  on but the -i option of stat and record, which enabled inheritance,
  led to believe it was off by default.

  This patch fixes this logic by inverting the meaning of the -i option.
  By default inheritance is on whether you attach to a process (-p), a
  thread (-t) or start a process. If you pass -i, then you turn off
  inheritance. Turning off inheritance if you don't need it, helps
  limit perf resource usage as well.

  The patch also fixes perf stat -t xxxx and perf record -t xxxx
  which did not start the counters.

  Signed-off-by: Stephane Eranian <eranian@google.com>
--
 Documentation/perf-record.txt |    4 ++--
 Documentation/perf-stat.txt   |    4 ++--
 builtin-record.c              |   12 ++++++------
 builtin-stat.c                |   10 +++++-----
 4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 020d871..34e255f 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -69,8 +69,8 @@ OPTIONS
 	Output file name.
 
 -i::
---inherit::
-	Child tasks inherit counters.
+--no-inherit::
+	Child tasks do not inherit counters.
 -F::
 --freq=::
 	Profile at this frequency.
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 484080d..2cab8e8 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -31,8 +31,8 @@ OPTIONS
 	 hexadecimal event descriptor.
 
 -i::
---inherit::
-        child tasks inherit counters
+--no-inherit::
+        child tasks do not inherit counters
 -p::
 --pid=<pid>::
         stat events on existing pid
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6b77b28..0f467cf 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -54,7 +54,7 @@ static pid_t			target_tid			=     -1;
 static pid_t			*all_tids			=      NULL;
 static int			thread_num			=      0;
 static pid_t			child_pid			=     -1;
-static bool			inherit				=   true;
+static bool			no_inherit			=  false;
 static enum write_mode_t	write_mode			= WRITE_FORCE;
 static bool			call_graph			=  false;
 static bool			inherit_stat			=  false;
@@ -298,8 +298,8 @@ static void create_counter(int counter, int cpu)
 
 	attr->mmap		= track;
 	attr->comm		= track;
-	attr->inherit		= inherit;
-	if (target_pid == -1 && !system_wide) {
+	attr->inherit		= !no_inherit;
+	if (target_pid == -1 && target_tid == -1 && !system_wide) {
 		attr->disabled = 1;
 		attr->enable_on_exec = 1;
 	}
@@ -641,7 +641,7 @@ static int __cmd_record(int argc, const char **argv)
 		close(child_ready_pipe[0]);
 	}
 
-	if ((!system_wide && !inherit) || profile_cpu != -1) {
+	if ((!system_wide && no_inherit) || profile_cpu != -1) {
 		open_counters(profile_cpu);
 	} else {
 		nr_cpus = read_cpu_map();
@@ -821,8 +821,8 @@ static const struct option options[] = {
 		    "event period to sample"),
 	OPT_STRING('o', "output", &output_name, "file",
 		    "output file name"),
-	OPT_BOOLEAN('i', "inherit", &inherit,
-		    "child tasks inherit counters"),
+	OPT_BOOLEAN('i', "no-inherit", &no_inherit,
+		    "child tasks do not inherit counters"),
 	OPT_INTEGER('F', "freq", &user_freq,
 		    "profile at this frequency"),
 	OPT_INTEGER('m', "mmap-pages", &mmap_pages,
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index e619ac8..ff8c413 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -72,7 +72,7 @@ static unsigned int		nr_cpus				=  0;
 static int			run_idx				=  0;
 
 static int			run_count			=  1;
-static bool			inherit				=  true;
+static bool			no_inherit			= false;
 static bool			scale				=  true;
 static pid_t			target_pid			= -1;
 static pid_t			target_tid			= -1;
@@ -167,8 +167,8 @@ static int create_perf_stat_counter(int counter)
 				++ncreated;
 		}
 	} else {
-		attr->inherit	     = inherit;
-		if (target_pid == -1) {
+		attr->inherit = !no_inherit;
+		if (target_pid == -1 && target_tid == -1) {
 			attr->disabled = 1;
 			attr->enable_on_exec = 1;
 		}
@@ -518,8 +518,8 @@ static const struct option options[] = {
 	OPT_CALLBACK('e', "event", NULL, "event",
 		     "event selector. use 'perf list' to list available events",
 		     parse_events),
-	OPT_BOOLEAN('i', "inherit", &inherit,
-		    "child tasks inherit counters"),
+	OPT_BOOLEAN('i', "no-inherit", &no_inherit,
+		    "child tasks do not inherit counters"),
 	OPT_INTEGER('p', "pid", &target_pid,
 		    "stat events on existing process id"),
 	OPT_INTEGER('t', "tid", &target_tid,