Messages in this thread | | | From | Stephane Eranian <> | Date | Thu, 6 Sep 2018 08:04:02 -0700 | Subject | Re: [PATCHv3] perf tools: Add struct ordered_events_buffer layer |
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On Thu, Sep 6, 2018 at 6:29 AM Jiri Olsa <jolsa@redhat.com> wrote: > > On Mon, Sep 03, 2018 at 07:37:56PM -0700, Stephane Eranian wrote: > > SNIP > > > > > I think the code is correct now for the issue related to uninitialized pointer. > > But there is still one problem I found stressing the code with max_alloc_size. > > The way the following is written: > > > > if (!list_empty(cache)) { > > new = list_entry(cache->next, struct ordered_event, list); > > list_del(&new->list); > > } else if (oe->buffer) { > > new = oe->buffer + oe->buffer_idx; > > if (++oe->buffer_idx == MAX_SAMPLE_BUFFER) > > oe->buffer = NULL; > > } else if (oe->cur_alloc_size < oe->max_alloc_size) { > > size_t size = sizeof(*oe->buffer) MAX_SAMPLE_BUFFER * > > sizeof(*new); > > > > oe->buffer = malloc(size); > > if (!oe->buffer) { > > free_dup_event(oe, new_event); > > return NULL; > > } > > > > pr("alloc size %" PRIu64 "B (+%zu), max %" PRIu64 "B\n", > > oe->cur_alloc_size, size, oe->max_alloc_size); > > > > oe->cur_alloc_size += size; > > > > You can end up with oe->cur_alloc_size > oe->max_alloc_size in case > > the max limit is > > really low (< size_t size = sizeof (*oe->buffer) + MAX_SAMPLE_BUFFER * > > sizeof(*new); > > So I think to make sure you can never allocate more than the max, you > > have to do: > > > > size_t size = sizeof(*oe->buffer) MAX_SAMPLE_BUFFER * sizeof(*new); > > if (!list_empty(cache)) { > > new = list_entry(cache->next, struct ordered_event, list); > > list_del(&new->list); > > } else if (oe->buffer) { > > new = oe->buffer + oe->buffer_idx; > > if (++oe->buffer_idx == MAX_SAMPLE_BUFFER) > > oe->buffer = NULL; > > } else if ((oe->cur_alloc_size + size) < oe->max_alloc_size) { > > > > Then you will never allocate more than the max. > > I think with this change, we are okay. > > Tested-by: Stephane Eranian <eranian@google.com> > > yep, makes sense.. something like below then > I'll post it on top of the previous patch > Yes. This works. Thanks.
> thanks, > jirka > > > --- > diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c > index 87171e8fd70d..2d1d0f3c8f77 100644 > --- a/tools/perf/util/ordered-events.c > +++ b/tools/perf/util/ordered-events.c > @@ -101,6 +101,7 @@ static struct ordered_event *alloc_event(struct ordered_events *oe, > struct list_head *cache = &oe->cache; > struct ordered_event *new = NULL; > union perf_event *new_event; > + size_t size; > > new_event = dup_event(oe, event); > if (!new_event) > @@ -133,6 +134,8 @@ static struct ordered_event *alloc_event(struct ordered_events *oe, > * Removal of ordered event object moves it from events to > * the cache list. > */ > + size = sizeof(*oe->buffer) + MAX_SAMPLE_BUFFER * sizeof(*new); > + > if (!list_empty(cache)) { > new = list_entry(cache->next, struct ordered_event, list); > list_del(&new->list); > @@ -140,10 +143,7 @@ static struct ordered_event *alloc_event(struct ordered_events *oe, > new = &oe->buffer->event[oe->buffer_idx]; > if (++oe->buffer_idx == MAX_SAMPLE_BUFFER) > oe->buffer = NULL; > - } else if (oe->cur_alloc_size < oe->max_alloc_size) { > - size_t size = sizeof(*oe->buffer) + > - MAX_SAMPLE_BUFFER * sizeof(*new); > - > + } else if ((oe->cur_alloc_size + size) < oe->max_alloc_size) { > oe->buffer = malloc(size); > if (!oe->buffer) { > free_dup_event(oe, new_event);
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