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SubjectRe: [PATCH V3 06/15] perf tools: fix parse_events_terms() freeing local variable on error path
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

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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