| From: Tom Zanussi <tom.zanussi@linux.intel.com> |
| Date: Mon, 15 Jan 2018 20:52:04 -0600 |
| Subject: [PATCH 38/48] tracing: Add hist trigger support for variable |
| reference aliases |
| |
| Add support for alias=$somevar where alias can be used as |
| onmatch.xxx($alias). |
| |
| Aliases are a way of creating a new name for an existing variable, for |
| flexibly in making naming more clear in certain cases. For example in |
| the below the user perhaps feels that using $new_lat in the synthetic |
| event invocation is opaque or doesn't fit well stylistically with |
| previous triggers, so creates an alias of $new_lat named $latency and |
| uses that in the call instead: |
| |
| # echo 'hist:keys=next_pid:new_lat=common_timestamp.usecs' > |
| /sys/kernel/debug/tracing/events/sched/sched_switch/trigger |
| |
| # echo 'hist:keys=pid:latency=$new_lat: |
| onmatch(sched.sched_switch).wake2($latency,pid)' > |
| /sys/kernel/debug/tracing/events/synthetic/wake1/trigger |
| |
| Link: http://lkml.kernel.org/r/ef20a65d921af3a873a6f1e8c71407c926d5586f.1516069914.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> |
| (cherry picked from commit 53c5a4f99f1a5f6ba304453716da571f3e51bc79) |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| kernel/trace/trace_events_hist.c | 74 +++++++++++++++++++++++++++++++++++---- |
| 1 file changed, 67 insertions(+), 7 deletions(-) |
| |
| --- a/kernel/trace/trace_events_hist.c |
| +++ b/kernel/trace/trace_events_hist.c |
| @@ -228,6 +228,7 @@ enum hist_field_flags { |
| HIST_FIELD_FL_EXPR = 1 << 13, |
| HIST_FIELD_FL_VAR_REF = 1 << 14, |
| HIST_FIELD_FL_CPU = 1 << 15, |
| + HIST_FIELD_FL_ALIAS = 1 << 16, |
| }; |
| |
| struct var_defs { |
| @@ -1609,7 +1610,8 @@ static const char *hist_field_name(struc |
| |
| if (field->field) |
| field_name = field->field->name; |
| - else if (field->flags & HIST_FIELD_FL_LOG2) |
| + else if (field->flags & HIST_FIELD_FL_LOG2 || |
| + field->flags & HIST_FIELD_FL_ALIAS) |
| field_name = hist_field_name(field->operands[0], ++level); |
| else if (field->flags & HIST_FIELD_FL_TIMESTAMP) |
| field_name = "common_timestamp"; |
| @@ -2080,7 +2082,7 @@ static struct hist_field *create_hist_fi |
| |
| hist_field->hist_data = hist_data; |
| |
| - if (flags & HIST_FIELD_FL_EXPR) |
| + if (flags & HIST_FIELD_FL_EXPR || flags & HIST_FIELD_FL_ALIAS) |
| goto out; /* caller will populate */ |
| |
| if (flags & HIST_FIELD_FL_VAR_REF) { |
| @@ -2217,10 +2219,18 @@ static int init_var_ref(struct hist_fiel |
| } |
| } |
| |
| - ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL); |
| - if (!ref_field->name) { |
| - err = -ENOMEM; |
| - goto free; |
| + if (var_field->var.name) { |
| + ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL); |
| + if (!ref_field->name) { |
| + err = -ENOMEM; |
| + goto free; |
| + } |
| + } else if (var_field->name) { |
| + ref_field->name = kstrdup(var_field->name, GFP_KERNEL); |
| + if (!ref_field->name) { |
| + err = -ENOMEM; |
| + goto free; |
| + } |
| } |
| |
| ref_field->type = kstrdup(var_field->type, GFP_KERNEL); |
| @@ -2382,6 +2392,28 @@ parse_field(struct hist_trigger_data *hi |
| return field; |
| } |
| |
| +static struct hist_field *create_alias(struct hist_trigger_data *hist_data, |
| + struct hist_field *var_ref, |
| + char *var_name) |
| +{ |
| + struct hist_field *alias = NULL; |
| + unsigned long flags = HIST_FIELD_FL_ALIAS | HIST_FIELD_FL_VAR; |
| + |
| + alias = create_hist_field(hist_data, NULL, flags, var_name); |
| + if (!alias) |
| + return NULL; |
| + |
| + alias->fn = var_ref->fn; |
| + alias->operands[0] = var_ref; |
| + |
| + if (init_var_ref(alias, var_ref, var_ref->system, var_ref->event_name)) { |
| + destroy_hist_field(alias, 0); |
| + return NULL; |
| + } |
| + |
| + return alias; |
| +} |
| + |
| static struct hist_field *parse_atom(struct hist_trigger_data *hist_data, |
| struct trace_event_file *file, char *str, |
| unsigned long *flags, char *var_name) |
| @@ -2415,6 +2447,13 @@ static struct hist_field *parse_atom(str |
| if (hist_field) { |
| hist_data->var_refs[hist_data->n_var_refs] = hist_field; |
| hist_field->var_ref_idx = hist_data->n_var_refs++; |
| + if (var_name) { |
| + hist_field = create_alias(hist_data, hist_field, var_name); |
| + if (!hist_field) { |
| + ret = -ENOMEM; |
| + goto out; |
| + } |
| + } |
| return hist_field; |
| } |
| } else |
| @@ -2515,6 +2554,26 @@ static int check_expr_operands(struct hi |
| unsigned long operand1_flags = operand1->flags; |
| unsigned long operand2_flags = operand2->flags; |
| |
| + if ((operand1_flags & HIST_FIELD_FL_VAR_REF) || |
| + (operand1_flags & HIST_FIELD_FL_ALIAS)) { |
| + struct hist_field *var; |
| + |
| + var = find_var_field(operand1->var.hist_data, operand1->name); |
| + if (!var) |
| + return -EINVAL; |
| + operand1_flags = var->flags; |
| + } |
| + |
| + if ((operand2_flags & HIST_FIELD_FL_VAR_REF) || |
| + (operand2_flags & HIST_FIELD_FL_ALIAS)) { |
| + struct hist_field *var; |
| + |
| + var = find_var_field(operand2->var.hist_data, operand2->name); |
| + if (!var) |
| + return -EINVAL; |
| + operand2_flags = var->flags; |
| + } |
| + |
| if ((operand1_flags & HIST_FIELD_FL_TIMESTAMP_USECS) != |
| (operand2_flags & HIST_FIELD_FL_TIMESTAMP_USECS)) |
| return -EINVAL; |
| @@ -4648,7 +4707,8 @@ static void hist_field_print(struct seq_ |
| else if (hist_field->flags & HIST_FIELD_FL_CPU) |
| seq_puts(m, "cpu"); |
| else if (field_name) { |
| - if (hist_field->flags & HIST_FIELD_FL_VAR_REF) |
| + if (hist_field->flags & HIST_FIELD_FL_VAR_REF || |
| + hist_field->flags & HIST_FIELD_FL_ALIAS) |
| seq_putc(m, '$'); |
| seq_printf(m, "%s", field_name); |
| } |