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tracing: Add hist trigger snapshot() action
Add support for hist:handlerXXX($var).snapshot(), which will take a snapshot of the current trace buffer whenever handlerXXX is hit. As a first user, this also adds snapshot() action support for the onmax() handler i.e. hist:onmax($var).snapshot(). Also, the hist trigger key printing is moved into a separate function so the snapshot() action can print a histogram key outside the histogram display - add and use hist_trigger_print_key() for that purpose. Link: http://lkml.kernel.org/r/2f1a952c0dcd8aca8702ce81269581a692396d45.1550100284.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
Steven Rostedt (VMware)
parent
a35873a099
commit
a3785b7eca
@ -4919,6 +4919,9 @@ static const char readme_msg[] =
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"\t The available actions are:\n\n"
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"\t <synthetic_event>(param list) - generate synthetic event\n"
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"\t save(field,...) - save current event fields\n"
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#ifdef CONFIG_TRACER_SNAPSHOT
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"\t snapshot() - snapshot the trace buffer\n"
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#endif
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#endif
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;
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@ -396,6 +396,7 @@ enum handler_id {
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enum action_id {
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ACTION_SAVE = 1,
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ACTION_TRACE,
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ACTION_SNAPSHOT,
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};
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struct action_data {
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@ -454,6 +455,83 @@ struct action_data {
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};
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};
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struct track_data {
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u64 track_val;
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bool updated;
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unsigned int key_len;
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void *key;
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struct tracing_map_elt elt;
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struct action_data *action_data;
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struct hist_trigger_data *hist_data;
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};
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struct hist_elt_data {
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char *comm;
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u64 *var_ref_vals;
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char *field_var_str[SYNTH_FIELDS_MAX];
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};
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struct snapshot_context {
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struct tracing_map_elt *elt;
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void *key;
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};
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static void track_data_free(struct track_data *track_data)
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{
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struct hist_elt_data *elt_data;
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if (!track_data)
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return;
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kfree(track_data->key);
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elt_data = track_data->elt.private_data;
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if (elt_data) {
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kfree(elt_data->comm);
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kfree(elt_data);
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}
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kfree(track_data);
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}
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static struct track_data *track_data_alloc(unsigned int key_len,
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struct action_data *action_data,
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struct hist_trigger_data *hist_data)
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{
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struct track_data *data = kzalloc(sizeof(*data), GFP_KERNEL);
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struct hist_elt_data *elt_data;
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if (!data)
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return ERR_PTR(-ENOMEM);
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data->key = kzalloc(key_len, GFP_KERNEL);
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if (!data->key) {
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track_data_free(data);
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return ERR_PTR(-ENOMEM);
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}
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data->key_len = key_len;
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data->action_data = action_data;
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data->hist_data = hist_data;
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elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
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if (!elt_data) {
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track_data_free(data);
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return ERR_PTR(-ENOMEM);
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}
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data->elt.private_data = elt_data;
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elt_data->comm = kzalloc(TASK_COMM_LEN, GFP_KERNEL);
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if (!elt_data->comm) {
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track_data_free(data);
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return ERR_PTR(-ENOMEM);
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}
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return data;
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}
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static char last_hist_cmd[MAX_FILTER_STR_VAL];
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static char hist_err_str[MAX_FILTER_STR_VAL];
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@ -1726,12 +1804,6 @@ static struct hist_field *find_event_var(struct hist_trigger_data *hist_data,
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return hist_field;
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}
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struct hist_elt_data {
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char *comm;
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u64 *var_ref_vals;
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char *field_var_str[SYNTH_FIELDS_MAX];
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};
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static u64 hist_field_var_ref(struct hist_field *hist_field,
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struct tracing_map_elt *elt,
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struct ring_buffer_event *rbe,
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@ -3452,6 +3524,112 @@ static bool check_track_val(struct tracing_map_elt *elt,
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return data->track_data.check_val(track_val, var_val);
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}
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#ifdef CONFIG_TRACER_SNAPSHOT
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static bool cond_snapshot_update(struct trace_array *tr, void *cond_data)
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{
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/* called with tr->max_lock held */
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struct track_data *track_data = tr->cond_snapshot->cond_data;
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struct hist_elt_data *elt_data, *track_elt_data;
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struct snapshot_context *context = cond_data;
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u64 track_val;
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if (!track_data)
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return false;
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track_val = get_track_val(track_data->hist_data, context->elt,
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track_data->action_data);
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track_data->track_val = track_val;
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memcpy(track_data->key, context->key, track_data->key_len);
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elt_data = context->elt->private_data;
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track_elt_data = track_data->elt.private_data;
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if (elt_data->comm)
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memcpy(track_elt_data->comm, elt_data->comm, TASK_COMM_LEN);
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track_data->updated = true;
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return true;
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}
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static void save_track_data_snapshot(struct hist_trigger_data *hist_data,
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struct tracing_map_elt *elt, void *rec,
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struct ring_buffer_event *rbe, void *key,
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struct action_data *data,
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u64 *var_ref_vals)
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{
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struct trace_event_file *file = hist_data->event_file;
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struct snapshot_context context;
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context.elt = elt;
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context.key = key;
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tracing_snapshot_cond(file->tr, &context);
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}
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static void hist_trigger_print_key(struct seq_file *m,
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struct hist_trigger_data *hist_data,
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void *key,
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struct tracing_map_elt *elt);
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static struct action_data *snapshot_action(struct hist_trigger_data *hist_data)
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{
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unsigned int i;
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if (!hist_data->n_actions)
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return NULL;
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for (i = 0; i < hist_data->n_actions; i++) {
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struct action_data *data = hist_data->actions[i];
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if (data->action == ACTION_SNAPSHOT)
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return data;
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}
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return NULL;
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}
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static void track_data_snapshot_print(struct seq_file *m,
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struct hist_trigger_data *hist_data)
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{
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struct trace_event_file *file = hist_data->event_file;
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struct track_data *track_data;
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struct action_data *action;
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track_data = tracing_cond_snapshot_data(file->tr);
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if (!track_data)
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return;
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if (!track_data->updated)
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return;
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action = snapshot_action(hist_data);
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if (!action)
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return;
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seq_puts(m, "\nSnapshot taken (see tracing/snapshot). Details:\n");
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seq_printf(m, "\ttriggering value { %s(%s) }: %10llu",
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action->handler == HANDLER_ONMAX ? "onmax" : "onchange",
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action->track_data.var_str, track_data->track_val);
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seq_puts(m, "\ttriggered by event with key: ");
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hist_trigger_print_key(m, hist_data, track_data->key, &track_data->elt);
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seq_putc(m, '\n');
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}
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#else
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static bool cond_snapshot_update(struct trace_array *tr, void *cond_data)
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{
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return false;
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}
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static void save_track_data_snapshot(struct hist_trigger_data *hist_data,
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struct tracing_map_elt *elt, void *rec,
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struct ring_buffer_event *rbe, void *key,
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struct action_data *data,
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u64 *var_ref_vals) {}
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static void track_data_snapshot_print(struct seq_file *m,
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struct hist_trigger_data *hist_data) {}
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#endif /* CONFIG_TRACER_SNAPSHOT */
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static void track_data_print(struct seq_file *m,
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struct hist_trigger_data *hist_data,
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struct tracing_map_elt *elt,
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@ -3463,6 +3641,9 @@ static void track_data_print(struct seq_file *m,
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if (data->handler == HANDLER_ONMAX)
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seq_printf(m, "\n\tmax: %10llu", track_val);
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if (data->action == ACTION_SNAPSHOT)
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return;
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for (i = 0; i < hist_data->n_save_vars; i++) {
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struct hist_field *save_val = hist_data->save_vars[i]->val;
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struct hist_field *save_var = hist_data->save_vars[i]->var;
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@ -3513,9 +3694,21 @@ static void action_data_destroy(struct action_data *data)
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static void track_data_destroy(struct hist_trigger_data *hist_data,
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struct action_data *data)
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{
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struct trace_event_file *file = hist_data->event_file;
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destroy_hist_field(data->track_data.track_var, 0);
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destroy_hist_field(data->track_data.var_ref, 0);
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if (data->action == ACTION_SNAPSHOT) {
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struct track_data *track_data;
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track_data = tracing_cond_snapshot_data(file->tr);
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if (track_data && track_data->hist_data == hist_data) {
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tracing_snapshot_cond_disable(file->tr);
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track_data_free(track_data);
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}
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}
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kfree(data->track_data.var_str);
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action_data_destroy(data);
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@ -3646,6 +3839,26 @@ static int action_parse(char *str, struct action_data *data,
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data->track_data.save_data = save_track_data_vars;
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data->fn = ontrack_action;
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data->action = ACTION_SAVE;
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} else if (str_has_prefix(action_name, "snapshot")) {
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char *params = strsep(&str, ")");
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if (!str) {
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hist_err("action parsing: No closing paren found: %s", params);
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ret = -EINVAL;
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goto out;
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}
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if (handler == HANDLER_ONMAX)
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data->track_data.check_val = check_track_val_max;
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else {
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hist_err("action parsing: Handler doesn't support action: ", action_name);
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ret = -EINVAL;
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goto out;
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}
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data->track_data.save_data = save_track_data_snapshot;
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data->fn = ontrack_action;
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data->action = ACTION_SNAPSHOT;
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} else {
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char *params = strsep(&str, ")");
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@ -3942,6 +4155,8 @@ static int trace_action_create(struct hist_trigger_data *hist_data,
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static int action_create(struct hist_trigger_data *hist_data,
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struct action_data *data)
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{
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struct trace_event_file *file = hist_data->event_file;
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struct track_data *track_data;
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struct field_var *field_var;
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unsigned int i;
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char *param;
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@ -3950,6 +4165,21 @@ static int action_create(struct hist_trigger_data *hist_data,
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if (data->action == ACTION_TRACE)
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return trace_action_create(hist_data, data);
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if (data->action == ACTION_SNAPSHOT) {
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track_data = track_data_alloc(hist_data->key_size, data, hist_data);
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if (IS_ERR(track_data)) {
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ret = PTR_ERR(track_data);
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goto out;
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}
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ret = tracing_snapshot_cond_enable(file->tr, track_data,
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cond_snapshot_update);
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if (ret)
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track_data_free(track_data);
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goto out;
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}
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if (data->action == ACTION_SAVE) {
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if (hist_data->n_save_vars) {
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ret = -EEXIST;
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@ -4552,6 +4782,9 @@ static void print_actions(struct seq_file *m,
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for (i = 0; i < hist_data->n_actions; i++) {
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struct action_data *data = hist_data->actions[i];
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if (data->action == ACTION_SNAPSHOT)
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continue;
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if (data->handler == HANDLER_ONMAX)
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track_data_print(m, hist_data, elt, data);
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}
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@ -4946,10 +5179,10 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
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}
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}
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static void
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hist_trigger_entry_print(struct seq_file *m,
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struct hist_trigger_data *hist_data, void *key,
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struct tracing_map_elt *elt)
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static void hist_trigger_print_key(struct seq_file *m,
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struct hist_trigger_data *hist_data,
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void *key,
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struct tracing_map_elt *elt)
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{
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struct hist_field *key_field;
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char str[KSYM_SYMBOL_LEN];
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@ -5025,6 +5258,17 @@ hist_trigger_entry_print(struct seq_file *m,
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seq_puts(m, " ");
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seq_puts(m, "}");
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}
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static void hist_trigger_entry_print(struct seq_file *m,
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struct hist_trigger_data *hist_data,
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void *key,
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struct tracing_map_elt *elt)
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{
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const char *field_name;
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unsigned int i;
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hist_trigger_print_key(m, hist_data, key, elt);
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seq_printf(m, " hitcount: %10llu",
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tracing_map_read_sum(elt, HITCOUNT_IDX));
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@ -5091,6 +5335,8 @@ static void hist_trigger_show(struct seq_file *m,
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if (n_entries < 0)
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n_entries = 0;
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track_data_snapshot_print(m, hist_data);
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seq_printf(m, "\nTotals:\n Hits: %llu\n Entries: %u\n Dropped: %llu\n",
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(u64)atomic64_read(&hist_data->map->hits),
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n_entries, (u64)atomic64_read(&hist_data->map->drops));
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