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tracing: Add hist trigger support for clearing a trace 

Allow users to append 'clear' to an existing trigger in order to have
the hash table cleared.

This expands the hist trigger syntax from this:
    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont \
           [ if filter] >> event/trigger

to this:

    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont/clear \
          [ if filter] >> event/trigger

Link: http://lkml.kernel.org/r/ae15dd0d9b2f7af07a37c1ff682063e2dbcdf160.1457029949.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>
This commit is contained in:
Tom Zanussi 2016-03-03 12:54:47 -06:00 committed by Steven Rostedt
parent 83e99914c9
commit e86ae9baac
2 changed files with 26 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
kernel/trace/trace.c
View File

@ -3837,7 +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 [:pause][:continue][:clear]\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"
@ -3857,6 +3857,9 @@ static const char readme_msg[] =
"\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"
"\t The 'clear' parameter will clear the contents of a running\n"
"\t hist trigger and leave its current paused/active state\n"
"\t unchanged.\n\n"
#endif
;

24
kernel/trace/trace_events_hist.c
View File

@ -88,6 +88,7 @@ struct hist_trigger_attrs {
char *sort_key_str;
bool pause;
bool cont;
bool clear;
unsigned int map_bits;
};
@ -200,6 +201,8 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
else if ((strcmp(str, "cont") == 0) ||
(strcmp(str, "continue") == 0))
attrs->cont = true;
else if (strcmp(str, "clear") == 0)
attrs->clear = true;
else if (strncmp(str, "size=", strlen("size=")) == 0) {
int map_bits = parse_map_size(str);
@ -916,6 +919,21 @@ static struct event_trigger_ops *event_hist_get_trigger_ops(char *cmd,
return &event_hist_trigger_ops;
}
static void hist_clear(struct event_trigger_data *data)
{
struct hist_trigger_data *hist_data = data->private_data;
bool paused;
paused = data->paused;
data->paused = true;
synchronize_sched();
tracing_map_clear(hist_data->map);
data->paused = paused;
}
static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct trace_event_file *file)
@ -930,13 +948,15 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
test->paused = true;
else if (hist_data->attrs->cont)
test->paused = false;
else if (hist_data->attrs->clear)
hist_clear(test);
else
ret = -EEXIST;
goto out;
}
}
if (hist_data->attrs->cont) {
if (hist_data->attrs->cont || hist_data->attrs->clear) {
ret = -ENOENT;
goto out;
}
@ -1035,7 +1055,7 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
* triggers registered a failure too.
*/
if (!ret) {
if (!(attrs->pause || attrs->cont))
if (!(attrs->pause || attrs->cont || attrs->clear))
ret = -ENOENT;
goto out_free;
} else if (ret < 0)