Re: [RFC Patch bpf-next] bpf: introduce bpf timer

From: Cong Wang <xiyou.wangcong@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>,
	duanxiongchun@bytedance.com,
	Dongdong Wang <wangdongdong.6@bytedance.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Cong Wang <cong.wang@bytedance.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>
Subject: Re: [RFC Patch bpf-next] bpf: introduce bpf timer
Date: Thu, 15 Apr 2021 08:51:22 -0700	[thread overview]
Message-ID: <CAM_iQpVc=0YtKLdEZNPDjA5H84UH50pZ4uFjQ1h=qO-+eUJn-Q@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQLsmULxJYq9rHS4xyg=VAUeexJTh35vTWTVgjeqwX4D6g@mail.gmail.com>

On Wed, Apr 14, 2021 at 9:25 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> As I said earlier:
> "
> If prog refers such hmap as above during prog free the kernel does
> for_each_map_elem {if (elem->opaque) del_timer().}
> "

This goes back to our previous discussion. Forcing timer deletions on
prog exit is not what we want. The whole point of using a map is to
extend the lifetime of a timer, that is, as long as the map exists, the
timers within it could be still running too.

Thanks.