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tracing: Add alternative synthetic event trace action syntax

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Add a 'trace(synthetic_event_name, params)' alternative to
synthetic_event_name(params).

Currently, the syntax used for generating synthetic events is to
invoke synthetic_event_name(params) i.e. use the synthetic event name
as a function call.

Users requested a new form that more explicitly shows that the
synthetic event is in effect being traced.  In this version, a new
'trace()' keyword is used, and the synthetic event name is passed in
as the first argument.

In addition, for the sake of consistency with other actions, change
the documention to emphasize the trace() form over the function-call
form, which remains documented as equivalent.

Link: http://lkml.kernel.org/r/d082773e50232a001480cf837679a1e01c1a2eb7.1550100284.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 17:42:50 -06:00
committed by Steven Rostedt (VMware)
parent ff0d35e2e1
commit e91eefd731
3 changed files with 75 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

42
kernel/trace/trace_events_hist.c
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@@ -419,6 +419,8 @@ struct action_data {
*/
unsigned int var_ref_idx;
struct synth_event *synth_event;
bool use_trace_keyword;
char *synth_event_name;
union {
struct {
@@ -3700,6 +3702,8 @@ static void action_data_destroy(struct action_data *data)
if (data->synth_event)
data->synth_event->ref--;
kfree(data->synth_event_name);
kfree(data);
}
@@ -3781,6 +3785,7 @@ static int track_data_create(struct hist_trigger_data *hist_data,
static int parse_action_params(char *params, struct action_data *data)
{
char *param, *saved_param;
bool first_param = true;
int ret = 0;
while (params) {
@@ -3809,6 +3814,13 @@ static int parse_action_params(char *params, struct action_data *data)
goto out;
}
if (first_param && data->use_trace_keyword) {
data->synth_event_name = saved_param;
first_param = false;
continue;
}
first_param = false;
data->params[data->n_params++] = saved_param;
}
out:
@@ -3886,6 +3898,9 @@ static int action_parse(char *str, struct action_data *data,
} else {
char *params = strsep(&str, ")");
if (str_has_prefix(action_name, "trace"))
data->use_trace_keyword = true;
if (params) {
ret = parse_action_params(params, data);
if (ret)
@@ -4088,13 +4103,19 @@ static int trace_action_create(struct hist_trigger_data *hist_data,
unsigned int i, var_ref_idx;
unsigned int field_pos = 0;
struct synth_event *event;
char *synth_event_name;
int ret = 0;
lockdep_assert_held(&event_mutex);
event = find_synth_event(data->action_name);
if (data->use_trace_keyword)
synth_event_name = data->synth_event_name;
else
synth_event_name = data->action_name;
event = find_synth_event(synth_event_name);
if (!event) {
hist_err("trace action: Couldn't find synthetic event: ", data->action_name);
hist_err("trace action: Couldn't find synthetic event: ", synth_event_name);
return -EINVAL;
}
@@ -4841,8 +4862,10 @@ static void print_action_spec(struct seq_file *m,
seq_puts(m, ",");
}
} else if (data->action == ACTION_TRACE) {
if (data->use_trace_keyword)
seq_printf(m, "%s", data->synth_event_name);
for (i = 0; i < data->n_params; i++) {
if (i)
if (i || data->use_trace_keyword)
seq_puts(m, ",");
seq_printf(m, "%s", data->params[i]);
}
@@ -4890,6 +4913,7 @@ static bool actions_match(struct hist_trigger_data *hist_data,
for (i = 0; i < hist_data->n_actions; i++) {
struct action_data *data = hist_data->actions[i];
struct action_data *data_test = hist_data_test->actions[i];
char *action_name, *action_name_test;
if (data->handler != data_test->handler)
return false;
@@ -4904,7 +4928,17 @@ static bool actions_match(struct hist_trigger_data *hist_data,
return false;
}
if (strcmp(data->action_name, data_test->action_name) != 0)
if (data->use_trace_keyword)
action_name = data->synth_event_name;
else
action_name = data->action_name;
if (data_test->use_trace_keyword)
action_name_test = data_test->synth_event_name;
else
action_name_test = data_test->action_name;
if (strcmp(action_name, action_name_test) != 0)
return false;
if (data->handler == HANDLER_ONMATCH) {