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SubjectRe: [PATCH V3 06/15] perf tools: fix parse_events_terms() freeing local variable on error path
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@intel.com>
>>> ---
>>> 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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