On 05-Jun-23 12:40 PM, Mark Rutland wrote:
> On Sun, Jun 04, 2023 at 01:38:10PM +0200, Krzysztof Kozlowski wrote:
>> Hi,
>>
>> #regzbot introduced: 9551fbb64d09
>>
>> Bisect pointed to commit 9551fbb64d09 ("perf/core: Remove pmu linear
>> searching code") as first one where all hardware events are gone from
>> perf for ARMv7 Exynos5422 board.
>
> I think that commit 9551fbb64d09 is just wrong.
>
> The commit message asserts:
>
> Searching for the right pmu by iterating over all pmus is no longer
> required since all pmus now *must* be present in the 'pmu_idr' list.
> So, remove linear searching code.
>
> ... and while each PMU has *some* entry in the pmu_idr list, for its dynamic
> type, that means that events with other types (e.g. PERF_TYPE_HARDWARE or
> PERF_TYPE_RAW) will fail to find a PMU in the IDR whereas they'd previously
> have been accepted by a PMU during the subsequent iteration over all PMUs.
Not sure I follow.
PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE are aliased to PERF_TYPE_RAW in
perf_init_event(). And PERF_TYPE_RAW should be present in pmu_idr if it
was registered using:
perf_pmu_register(pmu, "name", PERF_TYPE_RAW);
In fact, all static pmu types (enum perf_type_id) are also added to pmu_idr.
See (type >= 0) checks in perf_pmu_register() code:
if (type >= 0)
max = type;
ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
if (ret < 0)
goto free_pdc;
WARN_ON(type >= 0 && ret != type);
Thanks,
Ravi
