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Date: Fri, 16 Oct 2015 15:12:20 -0700 From: Alexei Starovoitov <ast@...mgrid.com> To: Kaixu Xia <xiakaixu@...wei.com>, davem@...emloft.net, acme@...nel.org, mingo@...hat.com, a.p.zijlstra@...llo.nl, masami.hiramatsu.pt@...achi.com, jolsa@...nel.org, daniel@...earbox.net Cc: wangnan0@...wei.com, linux-kernel@...r.kernel.org, pi3orama@....com, hekuang@...wei.com, netdev@...r.kernel.org Subject: Re: [PATCH V3 2/2] bpf: control all the perf events stored in PERF_EVENT_ARRAY maps On 10/16/15 12:42 AM, Kaixu Xia wrote: > This patch implements the function that controlling all the perf > events stored in PERF_EVENT_ARRAY maps by setting the parameter > 'index' to maps max_entries. > > Signed-off-by: Kaixu Xia <xiakaixu@...wei.com> > --- > kernel/trace/bpf_trace.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 3175600..4b385863 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -229,13 +229,30 @@ static u64 bpf_perf_event_dump_control(u64 r1, u64 index, u64 flag, u64 r4, u64 > 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; > + int i; > > - if (unlikely(index >= array->map.max_entries)) > + if (unlikely(index > array->map.max_entries)) > return -E2BIG; > > if (flag & BIT_FLAG_CHECK) > return -EINVAL; > > + if (index == array->map.max_entries) { I don't like in-band signaling like this, since it's easy to make mistake on the bpf program side. Please use 2nd bit of 'flags' for that instead. Also squash this patch into 1st. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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