Subject: Re: [PATCH v2 1/5] bpf: Add new bpf map type to store the pointer to
 struct perf_event
To: "Wangnan (F)" <wangnan0@huawei.com>, Kaixu Xia <xiakaixu@huawei.com>,
        davem@davemloft.net, acme@kernel.org, mingo@redhat.com,
        a.p.zijlstra@chello.nl, masami.hiramatsu.pt@hitachi.com,
        jolsa@kernel.org
References: <1437552572-84748-1-git-send-email-xiakaixu@huawei.com>
 <1437552572-84748-2-git-send-email-xiakaixu@huawei.com>
 <55B039F7.8060706@plumgrid.com> <55B03E99.7000803@huawei.com>
Cc: linux-kernel@vger.kernel.org, pi3orama@163.com, hekuang@huawei.com
From: Alexei Starovoitov <ast@plumgrid.com>
Message-ID: <55B045C0.3080606@plumgrid.com>
Date: Wed, 22 Jul 2015 18:39:12 -0700
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On 7/22/15 6:08 PM, Wangnan (F) wrote:
> Then we should find another way to prevent user create a large map but
> only use
> a small portion of it, since normal array map can't report whether a
> slot is used
> or not. When releasing the map, we have to release each perf event.
> Currently the only
> way is to check map value in each slot.

yeah. In prog_array each element is either NULL ptr or valid
'struct bpf_prog *'. Why not to do the same for perf_event_array?

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