On 08/30/2016 04:20 PM, Daniel Wagner wrote:
Just setting the size of the type is not enough. The hist_field_* getter function want to know the offset too:
With this hack here it should work. The COMM generic field is handled via the tracing_map_ops. We could do it also there but than we need to a condition in the trace_map_ops if it is COMM or CPU. This shortcut here avoids it:
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 03c0a48..ab8958f 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -152,7 +152,8 @@ EXPORT_SYMBOL_GPL(trace_define_field);
#define __generic_field(type, item, filter_type) \ ret = __trace_define_field(&ftrace_generic_fields, #type, \ - #item, 0, 0, is_signed_type(type), \ + #item, 0, sizeof(type), \ + is_signed_type(type), \ filter_type); \ if (ret) \ return ret; diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index f3a960e..77073b7 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -75,6 +75,11 @@ static u64 hist_field_log2(struct hist_field *hist_field, void *event) return (u64) ilog2(roundup_pow_of_two(val)); }
+static u64 hist_field_cpu(struct hist_field *hist_field, void *event) +{ + return (u64) smp_processor_id(); +} + #define DEFINE_HIST_FIELD_FN(type) \ static u64 hist_field_##type(struct hist_field *hist_field, void *event)\ { \ @@ -119,6 +124,7 @@ enum hist_field_flags { HIST_FIELD_FL_SYSCALL = 128, HIST_FIELD_FL_STACKTRACE = 256, HIST_FIELD_FL_LOG2 = 512, + HIST_FIELD_FL_CPU = 1024, };
struct hist_trigger_attrs { @@ -371,6 +377,11 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field, goto out; }
+ if (flags & HIST_FIELD_FL_CPU) { + hist_field->fn = hist_field_cpu; + goto out; + } + if (WARN_ON_ONCE(!field)) goto out;
@@ -556,6 +567,11 @@ static int create_key_field(struct hist_trigger_data *hist_data, key_size = MAX_FILTER_STR_VAL; else key_size = field->size; + + // strcmp(field_name, "cpu") would also work to figure + // out if this is a one of the generic fields. + if (field->filter_type == FILTER_CPU) + flags |= HIST_FIELD_FL_CPU; }
hist_data->fields[key_idx] = create_hist_field(field, flags);