[PATCH 4.19.y 11/13] tracing: Split up onmatch action data

George Guo
2024-05-09T02:30:35Z

From: Tom Zanussi <tom.zanussi@linux.intel.com>

commit c3e49506a0f426a850675e39419879214060ca8b upstream.

Currently, the onmatch action data binds the onmatch action to data
related to synthetic event generation. Since we want to allow the
onmatch handler to potentially invoke a different action, and because
we expect other handlers to generate synthetic events, we need to
separate the data related to these two functions.

Also rename the onmatch data to something more descriptive, and create
and use common action data destroy function.

Link: http://lkml.kernel.org/r/b9abbf9aae69fe3920cdc8ddbcaad544dd258d78.1550100284.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>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
kernel/trace/trace.c | 12 +++-
kernel/trace/trace_events_hist.c | 95 +++++++++++++++++---------------
2 files changed, 63 insertions(+), 44 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 559f2ad02a41..8292c7441e23 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4754,6 +4754,7 @@ static const char readme_msg[] =
"\t [:size=#entries]\n"
"\t [:pause][:continue][:clear]\n"
"\t [:name=histname1]\n"
+ "\t [:<handler>.<action>]\n"
"\t [if <filter>]\n\n"
"\t Note, special fields can be used as well:\n"
"\t common_timestamp - to record current timestamp\n"
@@ -4799,7 +4800,16 @@ static const char readme_msg[] =
"\t The enable_hist and disable_hist triggers can be used to\n"
"\t have one event conditionally start and stop another event's\n"
"\t already-attached hist trigger. The syntax is analagous to\n"
- "\t the enable_event and disable_event triggers.\n"
+ "\t the enable_event and disable_event triggers.\n\n"
+ "\t Hist trigger handlers and actions are executed whenever a\n"
+ "\t a histogram entry is added or updated. They take the form:\n\n"
+ "\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 The available actions are:\n\n"
+ "\t <synthetic_event>(param list) - generate synthetic event\n"
+ "\t save(field,...) - save current event fields\n"
#endif
;

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 70679defb6ee..e8f0ad253cce 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -379,13 +379,22 @@ struct action_data {
unsigned int n_params;
char *params[SYNTH_FIELDS_MAX];

+ /*
+ * When a histogram trigger is hit, the values of any
+ * references to variables, including variables being passed
+ * as parameters to synthetic events, are collected into a
+ * var_ref_vals array. This var_ref_idx is the index of the
+ * first param in the array to be passed to the synthetic
+ * event invocation.
+ */
+ unsigned int var_ref_idx;
+ struct synth_event *synth_event;
+
union {
struct {
- unsigned int var_ref_idx;
- char *match_event;
- char *match_event_system;
- struct synth_event *synth_event;
- } onmatch;
+ char *event;
+ char *event_system;
+ } match_data;

struct {
char *var_str;
@@ -1080,9 +1089,9 @@ static void action_trace(struct hist_trigger_data *hist_data,
struct ring_buffer_event *rbe, void *key,
struct action_data *data, u64 *var_ref_vals)
{
- struct synth_event *event = data->onmatch.synth_event;
+ struct synth_event *event = data->synth_event;

- trace_synth(event, var_ref_vals, data->onmatch.var_ref_idx);
+ trace_synth(event, var_ref_vals, data->var_ref_idx);
}

struct hist_var_data {
@@ -1648,8 +1657,8 @@ find_match_var(struct hist_trigger_data *hist_data, char *var_name)
struct action_data *data = hist_data->actions[i];

if (data->handler == HANDLER_ONMATCH) {
- char *system = data->onmatch.match_event_system;
- char *event_name = data->onmatch.match_event;
+ char *system = data->match_data.event_system;
+ char *event_name = data->match_data.event;

file = find_var_file(tr, system, event_name, var_name);
if (!file)
@@ -3490,22 +3499,33 @@ static void onmax_save(struct hist_trigger_data *hist_data,
update_max_vars(hist_data, elt, rbe, rec);
}

-static void onmax_destroy(struct action_data *data)
+static void action_data_destroy(struct action_data *data)
{
unsigned int i;

- destroy_hist_field(data->onmax.max_var, 0);
- destroy_hist_field(data->onmax.var, 0);
+ lockdep_assert_held(&event_mutex);

- kfree(data->onmax.var_str);
kfree(data->action_name);

for (i = 0; i < data->n_params; i++)
kfree(data->params[i]);

+ if (data->synth_event)
+ data->synth_event->ref--;
+
kfree(data);
}

+static void onmax_destroy(struct action_data *data)
+{
+ destroy_hist_field(data->onmax.max_var, 0);
+ destroy_hist_field(data->onmax.var, 0);
+
+ kfree(data->onmax.var_str);
+
+ action_data_destroy(data);
+}
+
static int action_create(struct hist_trigger_data *hist_data,
struct action_data *data);

@@ -3685,21 +3705,10 @@ static struct action_data *onmax_parse(char *str, enum handler_id handler)

static void onmatch_destroy(struct action_data *data)
{
- unsigned int i;
-
- lockdep_assert_held(&event_mutex);
+ kfree(data->match_data.event);
+ kfree(data->match_data.event_system);

- kfree(data->onmatch.match_event);
- kfree(data->onmatch.match_event_system);
- kfree(data->action_name);
-
- for (i = 0; i < data->n_params; i++)
- kfree(data->params[i]);
-
- if (data->onmatch.synth_event)
- data->onmatch.synth_event->ref--;
-
- kfree(data);
+ action_data_destroy(data);
}

static void destroy_field_var(struct field_var *field_var)
@@ -3760,8 +3769,8 @@ trace_action_find_var(struct hist_trigger_data *hist_data,
hist_field = find_target_event_var(hist_data, system, event, var);
if (!hist_field) {
if (!system && data->handler == HANDLER_ONMATCH) {
- system = data->onmatch.match_event_system;
- event = data->onmatch.match_event;
+ system = data->match_data.event_system;
+ event = data->match_data.event;
}

hist_field = find_event_var(hist_data, system, event, var);
@@ -3800,8 +3809,8 @@ trace_action_create_field_var(struct hist_trigger_data *hist_data,
* event.
*/
if (!system && data->handler == HANDLER_ONMATCH) {
- system = data->onmatch.match_event_system;
- event = data->onmatch.match_event;
+ system = data->match_data.event_system;
+ event = data->match_data.event;
}

if (!event)
@@ -3913,8 +3922,8 @@ static int trace_action_create(struct hist_trigger_data *hist_data,
goto err;
}

- data->onmatch.synth_event = event;
- data->onmatch.var_ref_idx = var_ref_idx;
+ data->synth_event = event;
+ data->var_ref_idx = var_ref_idx;
out:
return ret;
err:
@@ -4000,14 +4009,14 @@ static struct action_data *onmatch_parse(struct trace_array *tr, char *str)
goto free;
}

- data->onmatch.match_event = kstrdup(match_event, GFP_KERNEL);
- if (!data->onmatch.match_event) {
+ data->match_data.event = kstrdup(match_event, GFP_KERNEL);
+ if (!data->match_data.event) {
ret = -ENOMEM;
goto free;
}

- data->onmatch.match_event_system = kstrdup(match_event_system, GFP_KERNEL);
- if (!data->onmatch.match_event_system) {
+ data->match_data.event_system = kstrdup(match_event_system, GFP_KERNEL);
+ if (!data->match_data.event_system) {
ret = -ENOMEM;
goto free;
}
@@ -4579,8 +4588,8 @@ static void print_onmatch_spec(struct seq_file *m,
struct hist_trigger_data *hist_data,
struct action_data *data)
{
- seq_printf(m, ":onmatch(%s.%s).", data->onmatch.match_event_system,
- data->onmatch.match_event);
+ seq_printf(m, ":onmatch(%s.%s).", data->match_data.event_system,
+ data->match_data.event);

seq_printf(m, "%s(", data->action_name);

@@ -4618,11 +4627,11 @@ static bool actions_match(struct hist_trigger_data *hist_data,
return false;

if (data->handler == HANDLER_ONMATCH) {
- if (strcmp(data->onmatch.match_event_system,
- data_test->onmatch.match_event_system) != 0)
+ if (strcmp(data->match_data.event_system,
+ data_test->match_data.event_system) != 0)
return false;
- if (strcmp(data->onmatch.match_event,
- data_test->onmatch.match_event) != 0)
+ if (strcmp(data->match_data.event,
+ data_test->match_data.event) != 0)
return false;
} else if (data->handler == HANDLER_ONMAX) {
if (strcmp(data->onmax.var_str,
--
2.34.1