Re: [PATCH 6/6] perf parse events: demystify memory allocations

[David Ahern]

On 7/7/13 9:26 AM, Jiri Olsa wrote:
On Tue, Jul 02, 2013 at 01:27:25PM -0600, David Ahern wrote:
List heads are currently allocated way down the function chain in __add_event
and add_tracepoint and then freed when the scanner code calls
parse_events_update_lists.
Be more explicit with where memory is allocated and who should free it. With
this patch the list_head is allocated in the scanner code and freed when the
scanner code calls parse_events_update_lists.


SNIP

@@ -266,9 +279,10 @@ event_legacy_mem:
  PE_PREFIX_MEM PE_VALUE ':' PE_MODIFIER_BP sep_dc
  {
        struct parse_events_evlist *data = _data;
-       struct list_head *list = NULL;
+       struct list_head *list;

-       ABORT_ON(parse_events_add_breakpoint(&list, &data->idx,
+       ALLOC_LIST(list);
+       ABORT_ON(parse_events_add_breakpoint(list, &data->idx,
                                             (void *) $2, $4));
        $$ = list;
  }
@@ -276,9 +290,10 @@ PE_PREFIX_MEM PE_VALUE ':' PE_MODIFIER_BP sep_dc
  PE_PREFIX_MEM PE_VALUE sep_dc
  {
        struct parse_events_evlist *data = _data;
-       struct list_head *list = NULL;
+       struct list_head *list;

-       ABORT_ON(parse_events_add_breakpoint(&list, &data->idx,
+       ALLOC_LIST(list);
+       ABORT_ON(parse_events_add_breakpoint(list, &data->idx,
                                             (void *) $2, NULL));

so who now frees the list if there's an error
in parse_events_add_breakpoint?

According to valgrind that memory is not freed prior to this patch, so 
this one does not introduce new leaks.


ditto for other ABORT_ON cases

I will whip up a patch to free memory on failure paths.

David

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