From: Tom Zanussi <tom.zanussi@linux.intel.com>
Allow users to append 'pause' or 'continue' to an existing trigger in
order to have it paused or to have a paused trace continue.
This expands the hist trigger syntax from this:
# echo hist:keys=xxx:vals=yyy:sort=zzz.descending \
[ if filter] >> event/trigger
to this:
# echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause or cont \
[ if filter] >> event/trigger
Link: http://lkml.kernel.org/r/b672a92c14702cb924cdf6fc27ea1809bed04907.1457029949.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 7 ++++++-
kernel/trace/trace_events_hist.c | 31 ++++++++++++++++++++++++++++---
2 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d16fa8e1cdbf..7d5c63dd410a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3837,6 +3837,7 @@ static const char readme_msg[] =
"\t [:values=<field1[,field2,...]>]\n"
"\t [:sort=<field1[,field2,...]>]\n"
"\t [:size=#entries]\n"
+ "\t [:pause][:continue]\n"
"\t [if <filter>]\n\n"
"\t When a matching event is hit, an entry is added to a hash\n"
"\t table using the key(s) and value(s) named, and the value of a\n"
@@ -3851,7 +3852,11 @@ static const char readme_msg[] =
"\t used to specify more or fewer than the default 2048 entries\n"
"\t for the hashtable size.\n\n"
"\t Reading the 'hist' file for the event will dump the hash\n"
- "\t table in its entirety to stdout."
+ "\t table in its entirety to stdout.\n\n"
+ "\t The 'pause' parameter can be used to pause an existing hist\n"
+ "\t trigger or to start a hist trigger but not log any events\n"
+ "\t until told to do so. 'continue' can be used to start or\n"
+ "\t restart a paused hist trigger.\n\n"
#endif
;
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 03ba4530c08c..e3fa9c89f125 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -86,6 +86,8 @@ struct hist_trigger_attrs {
char *keys_str;
char *vals_str;
char *sort_key_str;
+ bool pause;
+ bool cont;
unsigned int map_bits;
};
@@ -193,6 +195,11 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
attrs->vals_str = kstrdup(str, GFP_KERNEL);
else if (strncmp(str, "sort=", strlen("sort=")) == 0)
attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
+ else if (strcmp(str, "pause") == 0)
+ attrs->pause = true;
+ else if ((strcmp(str, "cont") == 0) ||
+ (strcmp(str, "continue") == 0))
+ attrs->cont = true;
else if (strncmp(str, "size=", strlen("size=")) == 0) {
int map_bits = parse_map_size(str);
@@ -871,7 +878,10 @@ static int event_hist_trigger_print(struct seq_file *m,
if (data->filter_str)
seq_printf(m, " if %s", data->filter_str);
- seq_puts(m, " [active]");
+ if (data->paused)
+ seq_puts(m, " [paused]");
+ else
+ seq_puts(m, " [active]");
seq_putc(m, '\n');
@@ -910,16 +920,30 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct trace_event_file *file)
{
+ struct hist_trigger_data *hist_data = data->private_data;
struct event_trigger_data *test;
int ret = 0;
list_for_each_entry_rcu(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
- ret = -EEXIST;
+ if (hist_data->attrs->pause)
+ test->paused = true;
+ else if (hist_data->attrs->cont)
+ test->paused = false;
+ else
+ ret = -EEXIST;
goto out;
}
}
+ if (hist_data->attrs->cont) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ if (hist_data->attrs->pause)
+ data->paused = true;
+
if (data->ops->init) {
ret = data->ops->init(data->ops, data);
if (ret < 0)
@@ -1011,7 +1035,8 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
* triggers registered a failure too.
*/
if (!ret) {
- ret = -ENOENT;
+ if (!(attrs->pause || attrs->cont))
+ ret = -ENOENT;
goto out_free;
} else if (ret < 0)
goto out_free;
--
2.8.0.rc3