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

xiakaixu
2015-07-24T01:57:32Z

于 2015/7/24 6:56, Alexei Starovoitov 写道:
> On 7/23/15 2:42 AM, Kaixu Xia wrote:
>> According to the perf_event_map_fd and index, the function
>> bpf_perf_event_read() can convert the corresponding map
>> value to the pointer to struct perf_event and return the
>> Hardware PMU counter value.
>>
>> Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
> ...
>> +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;
>
> probably ENOENT makes more sense here.
>
>> +
>> + if (event->state != PERF_EVENT_STATE_ACTIVE)
>> + return -ENOENT;
>
> and -EINVAL here?

Yeah, the errno is better.

Thanks!
>
>
> .
>