From: Tom Zanussi 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 Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_hist.c | 74 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 67 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 98be6ad883eb..32af523501bc 100644 --- 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(struct hist_field *field, 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_field(struct hist_trigger_data *hist_data, 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_field *ref_field, } } - 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 *hist_data, struct trace_event_file *file, 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(struct hist_trigger_data *hist_data, 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 hist_field *operand1, 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; @@ -4646,7 +4705,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field) 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); } -- 2.15.1