From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751699AbdGZCkY (ORCPT ); Tue, 25 Jul 2017 22:40:24 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:42346 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbdGZCkW (ORCPT ); Tue, 25 Jul 2017 22:40:22 -0400 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: namhyung@kernel.org X-Original-SENDERIP: 10.177.227.17 X-Original-MAILFROM: namhyung@kernel.org Date: Wed, 26 Jul 2017 11:40:19 +0900 From: Namhyung Kim To: Tom Zanussi Cc: rostedt@goodmis.org, tglx@linutronix.de, mhiramat@kernel.org, vedang.patel@intel.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, kernel-team@lge.com Subject: Re: [PATCH 23/32] tracing: Add 'onmatch' hist trigger action support Message-ID: <20170726024019.GA32043@sejong> References: <8411497118160688b13fcf500596f6094d2eabcd.1498510759.git.tom.zanussi@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8411497118160688b13fcf500596f6094d2eabcd.1498510759.git.tom.zanussi@linux.intel.com> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tom, On Mon, Jun 26, 2017 at 05:49:24PM -0500, Tom Zanussi wrote: > Add an 'onmatch(matching.event).(param list)' > hist trigger action which is invoked with the set of variables or > event fields named in the 'param list'. The result is the generation > of a synthetic event that consists of the values contained in those > variables and/or fields at the time the invoking event was hit. > > As an example the below defines a simple synthetic event using a > variable defined on the sched_wakeup_new event, and shows the event > definition with unresolved fields, since the sched_wakeup_new event > with the testpid variable hasn't been defined yet: > > # echo 'wakeup_new_test pid_t pid; int prio' >> \ > /sys/kernel/debug/tracing/synthetic_events > > # cat /sys/kernel/debug/tracing/synthetic_events > wakeup_new_test pid_t pid; int prio > > The following hist trigger both defines a testpid variable and > specifies an onmatch() trace action that uses that variable along with > a non-variable field to generate a wakeup_new_test synthetic event > whenever a sched_wakeup_new event occurs, which because of the 'if > comm == "cyclictest"' filter only happens when the executable is > cyclictest: > > # echo 'hist:keys=testpid=pid:\ > onmatch(sched.sched_wakeup_new).wakeup_new_test($testpid, prio) \ > if comm=="cyclictest"' >> \ > /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger > > Creating and displaying a histogram based on those events is now just > a matter of using the fields and new synthetic event in the > tracing/events/synthetic directory, as usual: > > # echo 'hist:keys=pid,prio:sort=pid,prio' >> \ > /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/trigger > > Signed-off-by: Tom Zanussi > --- [SNIP] > static void hist_trigger_elt_data_free(struct tracing_map_elt *elt) > { > + struct hist_trigger_data *hist_data = elt->map->private_data; > struct hist_elt_data *private_data = elt->private_data; > + unsigned int i, n_str; > + > + n_str = hist_data->n_field_var_str; > + > + for (i = 0; i < n_str; i++) > + kfree(private_data->field_var_str[i]); > > kfree(private_data->comm); > kfree(private_data); > @@ -1537,7 +1627,7 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt) > unsigned int size = TASK_COMM_LEN + 1; > struct hist_elt_data *elt_data; > struct hist_field *key_field; > - unsigned int i; > + unsigned int i, n_str; > > elt->private_data = elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL); > if (!elt_data) > @@ -1557,6 +1647,16 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt) > } > } > > + n_str = hist_data->n_field_var_str; > + > + for (i = 0; i < n_str; i++) { > + elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL); So the max length of a string variable is TASK_COMM_LEN, right? In addition, isn't it necessary for hist_trigger_elt_data_copy() to copy the field_var_str array? > + if (!elt_data->field_var_str[i]) { > + hist_trigger_elt_data_free(elt); > + return -ENOMEM; > + } > + } > + > return 0; > } [SNIP] > +static bool compatible_keys(struct hist_trigger_data *target_hist_data, > + struct hist_trigger_data *hist_data, > + unsigned int n_keys) > +{ > + struct hist_field *target_hist_field, *hist_field; > + unsigned int n, i, j; > + > + if (hist_data->n_fields - hist_data->n_vals != n_keys) > + return false; > + > + i = hist_data->n_vals; > + j = target_hist_data->n_vals; > + > + for (n = 0; n < n_keys; n++) { > + hist_field = hist_data->fields[i + n]; > + target_hist_field = hist_data->fields[j + n]; Shouldn't it be 'target_hist_field = target_hist_data->fields[j + n]'? ^^^^^^^^^^^^^^^^ > + > + if (strcmp(hist_field->type, target_hist_field->type) != 0) > + return false; > + if (hist_field->size != target_hist_field->size) > + return false; > + if (hist_field->is_signed != target_hist_field->is_signed) > + return false; > + } > + > + return true; > +} > + > +static struct hist_trigger_data * > +find_compatible_hist(struct hist_trigger_data *target_hist_data, > + struct trace_event_file *file) > +{ > + struct hist_trigger_data *hist_data; > + struct event_trigger_data *test; > + unsigned int n_keys; > + > + n_keys = target_hist_data->n_fields - target_hist_data->n_vals; > + > + list_for_each_entry_rcu(test, &file->triggers, list) { > + if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) { > + hist_data = test->private_data; > + > + if (compatible_keys(target_hist_data, hist_data, n_keys)) > + return hist_data; > + } > + } > + > + return NULL; > +} > + > +static struct trace_event_file *event_file(char *system, char *event_name) > +{ > + struct trace_event_file *file; > + struct trace_array *tr; > + > + tr = top_trace_array(); > + if (!tr) > + return ERR_PTR(-ENODEV); > + > + file = find_event_file(tr, system, event_name); > + if (!file) > + return ERR_PTR(-EINVAL); > + > + return file; > +} > + > +static struct hist_field * > +create_field_var_hist(struct hist_trigger_data *target_hist_data, > + char *system, char *event_name, char *field_name) IIUC this is needed to create a new hist on a match_event only to provide a variable for a field, right? I guess it's needed because adding a new variable is dangerous/unsafe for a running hist. It'd be nice if you could add more comments though. Thanks, Namhyung > +{ > + struct hist_field *event_var = ERR_PTR(-EINVAL); > + struct hist_trigger_data *hist_data; > + unsigned int i, n, first = true; > + struct field_var_hist *var_hist; > + struct trace_event_file *file; > + struct hist_field *key_field; > + struct trace_array *tr; > + char *saved_filter; > + char *cmd; > + int ret; > + > + if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX) > + return ERR_PTR(-EINVAL); > + > + tr = top_trace_array(); > + if (!tr) > + return ERR_PTR(-ENODEV); > + > + file = event_file(system, event_name); > + if (IS_ERR(file)) { > + ret = PTR_ERR(file); > + return ERR_PTR(ret); > + } > + > + hist_data = find_compatible_hist(target_hist_data, file); > + if (!hist_data) > + return ERR_PTR(-EINVAL); > + > + var_hist = kzalloc(sizeof(*var_hist), GFP_KERNEL); > + if (!var_hist) > + return ERR_PTR(-ENOMEM); > + > + cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL); > + if (!cmd) { > + kfree(var_hist); > + return ERR_PTR(-ENOMEM); > + } > + > + strcat(cmd, "keys="); > + > + for_each_hist_key_field(i, hist_data) { > + key_field = hist_data->fields[i]; > + if (!first) > + strcat(cmd, ","); > + strcat(cmd, key_field->field->name); > + first = false; > + } > + > + strcat(cmd, ":synthetic_"); > + strcat(cmd, field_name); > + strcat(cmd, "="); > + strcat(cmd, field_name); > + > + saved_filter = find_trigger_filter(hist_data, file); > + if (saved_filter) { > + strcat(cmd, " if "); > + strcat(cmd, saved_filter); > + } > + > + var_hist->cmd = kstrdup(cmd, GFP_KERNEL); > + if (!var_hist->cmd) { > + kfree(cmd); > + kfree(var_hist); > + return ERR_PTR(-ENOMEM); > + } > + > + var_hist->hist_data = hist_data; > + > + ret = event_hist_trigger_func(&trigger_hist_cmd, file, > + "", "hist", cmd); > + if (ret) { > + kfree(cmd); > + kfree(var_hist->cmd); > + kfree(var_hist); > + return ERR_PTR(ret); > + } > + > + strcpy(cmd, "synthetic_"); > + strcat(cmd, field_name); > + > + event_var = find_event_var(system, event_name, cmd); > + if (!event_var) { > + kfree(cmd); > + kfree(var_hist->cmd); > + kfree(var_hist); > + return ERR_PTR(-EINVAL); > + } > + > + n = target_hist_data->n_field_var_hists; > + target_hist_data->field_var_hists[n] = var_hist; > + target_hist_data->n_field_var_hists++; > + > + return event_var; > +}