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tracing: Add hist trigger onchange() handler

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Add support for a hist:onchange($var) handler, similar to the onmax()
handler but triggering whenever there's any change in $var, not just a
max.

Link: http://lkml.kernel.org/r/dfbc7e4ada242603e9ec3f049b5ad076a07dfd03.1550100284.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi 2019-02-13 17:42:48 -06:00 committed by Steven Rostedt (VMware)
parent fd451a3d92
commit dff81f5592
2 changed files with 52 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
kernel/trace/trace.c
View File

@ -4915,7 +4915,8 @@ static const char readme_msg[] =
"\t <handler>.<action>\n\n"
"\t The available handlers are:\n\n"
"\t onmatch(matching.event) - invoke on addition or update\n"
"\t onmax(var) - invoke if var exceeds current max\n\n"
"\t onmax(var) - invoke if var exceeds current max\n"
"\t onchange(var) - invoke action if var changes\n\n"
"\t The available actions are:\n\n"
"\t <synthetic_event>(param list) - generate synthetic event\n"
"\t save(field,...) - save current event fields\n"

58
kernel/trace/trace_events_hist.c
View File

@ -391,6 +391,7 @@ typedef bool (*check_track_val_fn_t) (u64 track_val, u64 var_val);
enum handler_id {
HANDLER_ONMATCH = 1,
HANDLER_ONMAX,
HANDLER_ONCHANGE,
};
enum action_id {
@ -1989,7 +1990,8 @@ static int parse_action(char *str, struct hist_trigger_attrs *attrs)
return ret;
if ((str_has_prefix(str, "onmatch(")) ||
(str_has_prefix(str, "onmax("))) {
(str_has_prefix(str, "onmax(")) ||
(str_has_prefix(str, "onchange("))) {
attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
if (!attrs->action_str[attrs->n_actions]) {
ret = -ENOMEM;
@ -3481,6 +3483,14 @@ static bool check_track_val_max(u64 track_val, u64 var_val)
return true;
}
static bool check_track_val_changed(u64 track_val, u64 var_val)
{
if (var_val == track_val)
return false;
return true;
}
static u64 get_track_val(struct hist_trigger_data *hist_data,
struct tracing_map_elt *elt,
struct action_data *data)
@ -3640,6 +3650,8 @@ static void track_data_print(struct seq_file *m,
if (data->handler == HANDLER_ONMAX)
seq_printf(m, "\n\tmax: %10llu", track_val);
else if (data->handler == HANDLER_ONCHANGE)
seq_printf(m, "\n\tchanged: %10llu", track_val);
if (data->action == ACTION_SNAPSHOT)
return;
@ -3727,14 +3739,14 @@ static int track_data_create(struct hist_trigger_data *hist_data,
track_data_var_str = data->track_data.var_str;
if (track_data_var_str[0] != '$') {
hist_err("For onmax(x), x must be a variable: ", track_data_var_str);
hist_err("For onmax(x) or onchange(x), x must be a variable: ", track_data_var_str);
return -EINVAL;
}
track_data_var_str++;
var_field = find_target_event_var(hist_data, NULL, NULL, track_data_var_str);
if (!var_field) {
hist_err("Couldn't find onmax variable: ", track_data_var_str);
hist_err("Couldn't find onmax or onchange variable: ", track_data_var_str);
return -EINVAL;
}
@ -3751,6 +3763,14 @@ static int track_data_create(struct hist_trigger_data *hist_data,
ret = PTR_ERR(track_var);
goto out;
}
if (data->handler == HANDLER_ONCHANGE)
track_var = create_var(hist_data, file, "__change", sizeof(u64), "u64");
if (IS_ERR(track_var)) {
hist_err("Couldn't create onchange variable: ", "__change");
ret = PTR_ERR(track_var);
goto out;
}
data->track_data.track_var = track_var;
ret = action_create(hist_data, data);
@ -3830,6 +3850,8 @@ static int action_parse(char *str, struct action_data *data,
if (handler == HANDLER_ONMAX)
data->track_data.check_val = check_track_val_max;
else if (handler == HANDLER_ONCHANGE)
data->track_data.check_val = check_track_val_changed;
else {
hist_err("action parsing: Handler doesn't support action: ", action_name);
ret = -EINVAL;
@ -3850,6 +3872,8 @@ static int action_parse(char *str, struct action_data *data,
if (handler == HANDLER_ONMAX)
data->track_data.check_val = check_track_val_max;
else if (handler == HANDLER_ONCHANGE)
data->track_data.check_val = check_track_val_changed;
else {
hist_err("action parsing: Handler doesn't support action: ", action_name);
ret = -EINVAL;
@ -3870,6 +3894,8 @@ static int action_parse(char *str, struct action_data *data,
if (handler == HANDLER_ONMAX)
data->track_data.check_val = check_track_val_max;
else if (handler == HANDLER_ONCHANGE)
data->track_data.check_val = check_track_val_changed;
if (handler != HANDLER_ONMATCH) {
data->track_data.save_data = action_trace;
@ -4700,7 +4726,8 @@ static void destroy_actions(struct hist_trigger_data *hist_data)
if (data->handler == HANDLER_ONMATCH)
onmatch_destroy(data);
else if (data->handler == HANDLER_ONMAX)
else if (data->handler == HANDLER_ONMAX ||
data->handler == HANDLER_ONCHANGE)
track_data_destroy(hist_data, data);
else
kfree(data);
@ -4736,6 +4763,15 @@ static int parse_actions(struct hist_trigger_data *hist_data)
ret = PTR_ERR(data);
break;
}
} else if ((len = str_has_prefix(str, "onchange("))) {
char *action_str = str + len;
data = track_data_parse(hist_data, action_str,
HANDLER_ONCHANGE);
if (IS_ERR(data)) {
ret = PTR_ERR(data);
break;
}
} else {
ret = -EINVAL;
break;
@ -4760,7 +4796,8 @@ static int create_actions(struct hist_trigger_data *hist_data)
ret = onmatch_create(hist_data, data);
if (ret)
break;
} else if (data->handler == HANDLER_ONMAX) {
} else if (data->handler == HANDLER_ONMAX ||
data->handler == HANDLER_ONCHANGE) {
ret = track_data_create(hist_data, data);
if (ret)
break;
@ -4785,7 +4822,8 @@ static void print_actions(struct seq_file *m,
if (data->action == ACTION_SNAPSHOT)
continue;
if (data->handler == HANDLER_ONMAX)
if (data->handler == HANDLER_ONMAX ||
data->handler == HANDLER_ONCHANGE)
track_data_print(m, hist_data, elt, data);
}
}
@ -4817,6 +4855,8 @@ static void print_track_data_spec(struct seq_file *m,
{
if (data->handler == HANDLER_ONMAX)
seq_puts(m, ":onmax(");
else if (data->handler == HANDLER_ONCHANGE)
seq_puts(m, ":onchange(");
seq_printf(m, "%s", data->track_data.var_str);
seq_printf(m, ").%s(", data->action_name);
@ -4874,7 +4914,8 @@ static bool actions_match(struct hist_trigger_data *hist_data,
if (strcmp(data->match_data.event,
data_test->match_data.event) != 0)
return false;
} else if (data->handler == HANDLER_ONMAX) {
} else if (data->handler == HANDLER_ONMAX ||
data->handler == HANDLER_ONCHANGE) {
if (strcmp(data->track_data.var_str,
data_test->track_data.var_str) != 0)
return false;
@ -4895,7 +4936,8 @@ static void print_actions_spec(struct seq_file *m,
if (data->handler == HANDLER_ONMATCH)
print_onmatch_spec(m, hist_data, data);
else if (data->handler == HANDLER_ONMAX)
else if (data->handler == HANDLER_ONMAX ||
data->handler == HANDLER_ONCHANGE)
print_track_data_spec(m, hist_data, data);
}
}