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    SubjectRe: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing
    On Fri, Jun 14, 2019 at 10:08:00PM +0800, John Garry wrote:
    > The jevent "Unit" field is used for uncore PMU alias definition.
    >
    > The form uncore_pmu_example_X is supported, where "X" is a wildcard,
    > to support multiple instances of the same PMU in a system.
    >
    > Unfortunately this format not suitable for all uncore PMUs; take the Hisi
    > DDRC uncore PMU for example, where the name is in the form
    > hisi_scclX_ddrcY.
    >
    > For the current jevent parsing, we would be required to hardcode an uncore
    > alias translation for each possible value of X. This is not scalable.
    >
    > Instead, add support for "Unit" field in the form "hisi_sccl,ddrc", where
    > we can match by hisi_scclX and ddrcY. Tokens in Unit field are
    > delimited by ','.
    >
    > Signed-off-by: John Garry <john.garry@huawei.com>
    > ---
    > tools/perf/util/pmu.c | 39 ++++++++++++++++++++++++++++++++++-----
    > 1 file changed, 34 insertions(+), 5 deletions(-)
    >
    > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
    > index 7e7299fee550..bc71c60589b5 100644
    > --- a/tools/perf/util/pmu.c
    > +++ b/tools/perf/util/pmu.c
    > @@ -700,6 +700,39 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
    > return map;
    > }
    >
    > +static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
    > +{
    > + char *tmp, *tok, *str;
    > + bool res;
    > +
    > + str = strdup(pmu_name);
    > + if (!str)
    > + return false;
    > +
    > + /*
    > + * uncore alias may be from different PMU with common
    > + * prefix or matching tokens.
    > + */
    > + tok = strtok_r(str, ",", &tmp);
    > + if (strncmp(pmu_name, tok, strlen(tok))) {

    if tok is NULL in here we crash

    > + res = false;
    > + goto out;
    > + }
    > +
    > + for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {

    why is name shifted in here?

    jirka

    > + name = strstr(name, tok);
    > + if (!name) {
    > + res = false;
    > + goto out;
    > + }
    > + }
    > +
    > + res = true;
    > +out:
    > + free(str);
    > + return res;
    > +}
    > +
    > /*
    > * From the pmu_events_map, find the table of PMU events that corresponds
    > * to the current running CPU. Then, add all PMU events from that table
    > @@ -730,12 +763,8 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
    > break;
    > }
    >
    > - /*
    > - * uncore alias may be from different PMU
    > - * with common prefix
    > - */
    > if (pmu_is_uncore(name) &&
    > - !strncmp(pname, name, strlen(pname)))
    > + pmu_uncore_alias_match(pname, name))
    > goto new_alias;
    >
    > if (strcmp(pname, name))
    > --
    > 2.17.1
    >

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