Re: [PATCH V3 06/15] perf tools: fix parse_events_terms() freeinglocal variable on error path

[David Ahern]

On 7/1/13 2:01 AM, Adrian Hunter wrote:
> On 28/06/13 20:19, David Ahern wrote:
> > On 6/28/13 2:43 AM, Adrian Hunter wrote:
> > > The list_head is on the stack, so just free the rest of the list.
> > >
> > > Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > > ---
> > >    tools/perf/util/parse-events.c | 7 ++++++-
> > >    tools/perf/util/parse-events.h | 1 +
> > >    tools/perf/util/pmu.c          | 2 +-
> > >    3 files changed, 8 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> > > index 995fc25..d9cb055 100644
> > > --- a/tools/perf/util/parse-events.c
> > > +++ b/tools/perf/util/parse-events.c
> > > @@ -1231,12 +1231,17 @@ int parse_events_term__clone(struct
> > > parse_events_term **new,
> > >                term->val.str, term->val.num);
> > >    }
> > >
> > > -void parse_events__free_terms(struct list_head *terms)
> > > +void parse_events__free_terms_only(struct list_head *terms)
> > >    {
> > >        struct parse_events_term *term, *h;
> > >
> > >        list_for_each_entry_safe(term, h, terms, list)
> > >            free(term);
> > > +}
> > > +
> > > +void parse_events__free_terms(struct list_head *terms)
> > > +{
> > > +    parse_events__free_terms_only(terms);
> > >
> > >        free(terms);
> > >    }
> >
> > I still don't understand the reasoning for an _only function. There is only
> > 1 place that mallocs the list_head and that 1 user should free its own
> > memory. All of the other users pass a stack variable.
>
> No.  See parse-events.y

Fine. Fix both then. My point is that parse-events.c code should not be 
freeing memory it does not allocate.

David


> The list head is defined as a pointer in the YYTYPE stack element:
>
> %union
> {
> 	char *str;
> 	u64 num;
> 	struct list_head *head;
> 	struct parse_events_term *term;
> }
>
> It is malloc'ed when terms are created:
>
> event_term
> {
> 	struct list_head *head = malloc(sizeof(*head));
> 	struct parse_events_term *term = $1;
>
> 	ABORT_ON(!head);
> 	INIT_LIST_HEAD(head);
> 	list_add_tail(&term->list, head);
> 	$$ = head;
> }

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