On Sun, 2015-07-19 at 22:31 +0900, Namhyung Kim wrote:
> On Thu, Jul 16, 2015 at 12:22:53PM -0500, Tom Zanussi wrote:
> > If we assume the maximum size for a string field, we don't have to
> > worry about its position. Since we only allow two keys in a compound
> > key and having more than one string key in a given compound key
> > doesn't make much sense anyway, trading a bit of extra space instead
> > of introducing an arbitrary restriction makes more sense.
> >
> > We also need to use the event field size for static strings when
> > copying the contents, otherwise we get random garbage in the key.
> >
> > Finally, rearrange the code without changing any functionality by
> > moving the compound key updating code into a separate function.
> >
> > Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
>
> Looks good to me. Just a nitpick below..
>
>
> > ---
> > kernel/trace/trace_events_hist.c | 65
> > +++++++++++++++++++++++-----------------
> > 1 file changed, 37 insertions(+), 28 deletions(-)
> >
> > diff --git a/kernel/trace/trace_events_hist.c
> > b/kernel/trace/trace_events_hist.c
> > index 67fffee..4ba7645 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -508,8 +508,8 @@ static int create_key_field(struct hist_trigger_data
> > *hist_data,
> > goto out;
> > }
> >
> > - if (is_string_field(field)) /* should be last key field */
> > - key_size = HIST_KEY_SIZE_MAX - key_offset;
> > + if (is_string_field(field))
> > + key_size = MAX_FILTER_STR_VAL;
> > else
> > key_size = field->size;
> > }
> > @@ -781,9 +781,36 @@ static void hist_trigger_elt_update(struct
> > hist_trigger_data *hist_data,
> > }
> > }
> >
> > +static inline void add_to_key(char *compound_key, void *key,
> > + struct hist_field *key_field, void *rec)
> > +{
> > + size_t size = key_field->size;
> > +
> > + if (key_field->flags & HIST_FIELD_STRING) {
> > + struct ftrace_event_field *field;
> > +
> > + /* ensure NULL-termination */
> > + size--;
>
> This is unnecessary since the size value will be updated below anyway.
> I think it's enough just to move the comment to ...
>
>
> > +
> > + field = key_field->field;
> > + if (field->filter_type == FILTER_DYN_STRING)
> > + size = *(u32 *)(rec + field->offset) >> 16;
> > + else if (field->filter_type == FILTER_PTR_STRING)
> > + size = strlen(key);
> > + else if (field->filter_type == FILTER_STATIC_STRING)
> > + size = field->size;
> > +
>
> ... here. :)
>
Yep, makes sense, will do.
Tom
> > + if (size > key_field->size - 1)
> > + size = key_field->size - 1;
> > + }
> > +
> > + memcpy(compound_key + key_field->offset, key, size);
> > +}
> > +
> > static void event_hist_trigger(struct event_trigger_data *data, void *rec)
> > {
> > struct hist_trigger_data *hist_data = data->private_data;
> > + bool use_compound_key = (hist_data->n_keys > 1);
> > unsigned long entries[HIST_STACKTRACE_DEPTH];
> > char compound_key[HIST_KEY_SIZE_MAX];
> > struct stack_trace stacktrace;
> > @@ -798,8 +825,7 @@ static void event_hist_trigger(struct
> > event_trigger_data *data, void *rec)
> > return;
> > }
> >
> > - if (hist_data->n_keys > 1)
> > - memset(compound_key, 0, hist_data->key_size);
> > + memset(compound_key, 0, hist_data->key_size);
> >
> > for (i = hist_data->n_vals; i < hist_data->n_fields; i++) {
> > key_field = hist_data->fields[i];
> > @@ -816,35 +842,18 @@ static void event_hist_trigger(struct
> > event_trigger_data *data, void *rec)
> > key = entries;
> > } else {
> > field_contents = key_field->fn(key_field, rec);
> > - if (key_field->flags & HIST_FIELD_STRING)
> > + if (key_field->flags & HIST_FIELD_STRING) {
> > key = (void *)field_contents;
> > - else
> > + use_compound_key = true;
> > + } else
> > key = (void *)&field_contents;
> > -
> > - if (hist_data->n_keys > 1) {
> > - /* ensure NULL-termination */
> > - size_t size = key_field->size - 1;
> > -
> > - if (key_field->flags & HIST_FIELD_STRING) {
> > - struct ftrace_event_field *field;
> > -
> > - field = key_field->field;
> > - if (field->filter_type ==
> > FILTER_DYN_STRING)
> > - size = *(u32 *)(rec +
> > field->offset) >> 16;
> > - else if (field->filter_type ==
> > FILTER_PTR_STRING)
> > - size = strlen(key);
> > -
> > - if (size > key_field->size - 1)
> > - size = key_field->size - 1;
> > - }
> > -
> > - memcpy(compound_key + key_field->offset, key,
> > - size);
> > - }
> > }
> > +
> > + if (use_compound_key)
> > + add_to_key(compound_key, key, key_field, rec);
> > }
> >
> > - if (hist_data->n_keys > 1)
> > + if (use_compound_key)
> > key = compound_key;
> >
> > elt = tracing_map_insert(hist_data->map, key);
> > --
> > 1.9.3
> >
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