Messages in this thread Patch in this message | | | Date | Mon, 12 Nov 2012 14:45:34 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 02/12] perf header: Add HEADER_GROUP_DESC feature |
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Em Sat, Nov 10, 2012 at 01:43:24AM +0900, Namhyung Kim escreveu: > From: Namhyung Kim <namhyung.kim@lge.com> > > Save group relationship information so that it can be restored when > perf report is running. > > Cc: Jiri Olsa <jolsa@redhat.com> > Cc: Stephane Eranian <eranian@google.com> > Acked-by: Jiri Olsa <jolsa@redhat.com> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
<SNIP>
> +static int process_group_desc(struct perf_file_section *section __maybe_unused, > + struct perf_header *ph, int fd, > + void *data __maybe_unused) > +{ > + size_t ret = -1;
why initialize ret if the first thing you do with it is...
> + u32 i, nr, nr_groups; > + struct perf_session *session; > + struct perf_evsel *evsel, *leader = NULL; > + struct group_desc { > + char *name; > + u32 leader_idx; > + u32 nr_members; > + } *desc; > + > + ret = read(fd, &nr_groups, sizeof(nr_groups));
assign another value?
We need to use readn instead of read, and not use ret here, just do if (read(fd, &nr_groups, sizeof(nr_groups)) != sizeof(nr_groups))
> + if (ret != sizeof(nr_groups)) > + return -1; > + > + if (ph->needs_swap) > + nr_groups = bswap_32(nr_groups); > + > + ph->env.nr_groups = nr_groups; > + if (!nr_groups) { > + pr_debug("group desc not available\n"); > + return 0; > + } > + > + desc = calloc(nr_groups, sizeof(*desc)); > + if (!desc) > + return -1; > + > + for (i = 0; i < nr_groups; i++) { > + desc[i].name = do_read_string(fd, ph); > + if (!desc[i].name) > + goto out_free; > + > + ret = read(fd, &desc[i].leader_idx, sizeof(u32)); > + if (ret != sizeof(u32)) > + goto out_free;
ditto
> + > + ret = read(fd, &desc[i].nr_members, sizeof(u32)); > + if (ret != sizeof(u32)) > + goto out_free;
ditto
> + > + if (ph->needs_swap) { > + desc[i].leader_idx = bswap_32(desc[i].leader_idx); > + desc[i].nr_members = bswap_32(desc[i].nr_members); > + } > + } > + > + /* > + * Rebuild group relationship based on the group_desc > + */ > + session = container_of(ph, struct perf_session, header); > + session->evlist->nr_groups = nr_groups; > + > + i = nr = 0; > + list_for_each_entry(evsel, &session->evlist->entries, node) { > + if (evsel->idx == (int) desc[i].leader_idx) { > + evsel->leader = NULL;
Humm, isn't it better to set evsel->leader to evsel, that way all members in a group have its evsel->leader pointing to the leader and for things like the group idx we can do just:
evsel->idx - evsel->leader->idx
avoiding the need to special case the leader, will do that.
> + /* {anon_group} is a dummy name */ > + if (strcmp(desc[i].name, "{anon_group}")) > + evsel->group_name = desc[i].name; > + evsel->nr_members = desc[i].nr_members; > + > + BUG_ON(i >= nr_groups); > + BUG_ON(nr > 0);
BUG_ON here is way too extreme, we should just bail out, testing and if the problem is found, goto out_free
> + leader = evsel; > + nr = evsel->nr_members; > + i++; > + } else if (nr) {
Humm, do we really need to test against nr? Or even use nr at all?
> + /* This is a group member */ > + evsel->leader = leader; > + /* group_idx starts from 0 */ > + evsel->group_idx = leader->nr_members - nr; > + nr--; > + } > + } > + > + BUG_ON(i != nr_groups); > + BUG_ON(nr != 0);
Too extreme, goto out_free.
And just before out_free we need to set ret = 0, otherwise we will return...
> +out_free: > + while ((int) --i >= 0) > + free(desc[i].name); > + free(desc);
here, whatever value was in ret, in this patch it will be, if all goes well, sizeof(u32) :-)
> + return ret; > +} > + > struct feature_ops { > int (*write)(int fd, struct perf_header *h, struct perf_evlist *evlist); > void (*print)(struct perf_header *h, int fd, FILE *fp); > @@ -1986,6 +2137,7 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = { > FEAT_OPF(HEADER_NUMA_TOPOLOGY, numa_topology), > FEAT_OPA(HEADER_BRANCH_STACK, branch_stack), > FEAT_OPP(HEADER_PMU_MAPPINGS, pmu_mappings), > + FEAT_OPP(HEADER_GROUP_DESC, group_desc), > }; > > struct header_print_data { > diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h > index 5f1cd6884f37..e3e7fb490310 100644 > --- a/tools/perf/util/header.h > +++ b/tools/perf/util/header.h > @@ -29,6 +29,7 @@ enum { > HEADER_NUMA_TOPOLOGY, > HEADER_BRANCH_STACK, > HEADER_PMU_MAPPINGS, > + HEADER_GROUP_DESC, > HEADER_LAST_FEATURE, > HEADER_FEAT_BITS = 256, > };
Here we're adding holes to the struct:
> @@ -79,6 +80,7 @@ struct perf_session_env { > char *numa_nodes; > int nr_pmu_mappings;
4 byte hole
> char *pmu_mappings;
4 byte hole
> + int nr_groups;
I'm working on a patch implementing my suggestions.
> }; > struct perf_header { > -- > 1.7.9.2
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