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    SubjectRe: [PATCH 2/3] perf alias: Rebuild alias expression string to make it comparable
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    On 06/14/2018 06:48 AM, Thomas Richter wrote:
    > PMU alias definitions in sysfs files may have spaces, newlines
    > and number with leading zeroes. Same alias definitions may
    > also appear in JSON files without spaces, etc.
    >
    > Scan alias definitions and remove leading zeroes, spaces,
    > newlines, etc and rebuild string to make alias->str member
    > comparable.
    >
    > s390 for example has terms specified as
    > event=0x0091 (read from files ../<PMU>/events/<FILE>
    > and terms specified as event=0x91 (read from JSON files).
    >
    > Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
    > ---
    > tools/perf/util/pmu.c | 25 ++++++++++++++++++++++++-
    > 1 file changed, 24 insertions(+), 1 deletion(-)
    >
    > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
    > index 26c79a9c4142..da8f243743d3 100644
    > --- a/tools/perf/util/pmu.c
    > +++ b/tools/perf/util/pmu.c
    > @@ -241,9 +241,11 @@ static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name,
    > char *metric_expr,
    > char *metric_name)
    > {
    > + struct parse_events_term *term;
    > struct perf_pmu_alias *alias;
    > int ret;
    > int num;
    > + char newval[256];

    How was 256 chosen?

    >
    > alias = malloc(sizeof(*alias));
    > if (!alias)
    > @@ -262,6 +264,27 @@ static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name,
    > return ret;
    > }
    >
    > + /* Scan event and remove leading zeroes, spaces, newlines, some
    > + * platforms have terms specified as
    > + * event=0x0091 (read from files ../<PMU>/events/<FILE>
    > + * and terms specified as event=0x91 (read from JSON files).
    > + *
    > + * Rebuild string to make alias->str member comparable.
    > + */
    > + memset(newval, 0, sizeof(newval));
    > + ret = 0;
    > + list_for_each_entry(term, &alias->terms, list) {
    > + if (ret)
    > + ret += scnprintf(newval + ret, sizeof(newval) - ret,
    > + ",");
    > + if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM)
    > + ret += scnprintf(newval + ret, sizeof(newval) - ret,
    > + "%s=%#x", term->config, term->val.num);
    > + else if (term->type_val == PARSE_EVENTS__TERM_TYPE_STR)
    > + ret += scnprintf(newval + ret, sizeof(newval) - ret,
    > + "%s=%s", term->config, term->val.str);

    If we exceed 256, we just suddenly terminate the rebuilding without reporting any issues.

    > + }
    > +
    > alias->name = strdup(name);
    > if (dir) {
    > /*
    > @@ -285,7 +308,7 @@ static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name,
    > snprintf(alias->unit, sizeof(alias->unit), "%s", unit);
    > }
    > alias->per_pkg = perpkg && sscanf(perpkg, "%d", &num) == 1 && num == 1;
    > - alias->str = strdup(val);
    > + alias->str = strdup(newval);
    >
    > list_add_tail(&alias->list, list);
    >

    PC

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