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    SubjectRe: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing
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    On 16/06/2019 10:58, Jiri Olsa wrote:
    > 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))) {
    >

    Hi Jirka,

    > if tok is NULL in here we crash
    >

    As I see, tok could not be NULL. If str contains no delimiters, then we
    just return same as str in tok.

    Can you see tok being NULL?

    >> + res = false;
    >> + goto out;
    >> + }
    >> +
    >> + for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
    >
    > why is name shifted in here?

    I want to ensure that we match the tokens in order and also guard
    against possible repeated token matches in 'name'.

    Thanks,
    John

    >
    > 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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