Re: [PATCH v3 2/3] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter

xiakaixu
2015-08-03T10:35:10Z

于 2015/8/3 17:34, Peter Zijlstra 写道:
> On Thu, Jul 23, 2015 at 09:42:41AM +0000, Kaixu Xia wrote:
>> +static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
>> +{
>> + struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
>> + struct bpf_array *array = container_of(map, struct bpf_array, map);
>> + struct perf_event *event;
>> +
>> + if (index >= array->map.max_entries)
>> + return -E2BIG;
>> +
>> + event = array->events[index];
>> + if (!event)
>> + return -EBADF;
>> +
>> + if (event->state != PERF_EVENT_STATE_ACTIVE)
>> + return -ENOENT;
>> +
>> + if (event->oncpu != raw_smp_processor_id() &&
>> + event->ctx->task != current)
>> + return -EINVAL;
>> +
>> + if (event->attr.inherit)
>> + return -EINVAL;
>> +
>> + __perf_event_read(event);
>> +
>> + return perf_event_count(event);
>> +}
>
> Please no poking of event internal state outside of perf code.

Thanks for your review. I will move it to kernel/events/core.c.
>
> .
>