From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Martin Lau <kafai@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"andrii.nakryiko@gmail.com" <andrii.nakryiko@gmail.com>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [Potential Spoof] [PATCH bpf-next] libbpf: add bpf_link__disconnect() API to preserve underlying BPF resource
Date: Wed, 18 Dec 2019 17:19:07 -0800 [thread overview]
Message-ID: <CAADnVQLmrvnv=R6shyLwS61s7kO7=X5WbRur2kWu96FZAWidQg@mail.gmail.com> (raw)
In-Reply-To: <20191218231215.kzrdnupxs3ybv2zh@kafai-mbp.dhcp.thefacebook.com>
On Wed, Dec 18, 2019 at 3:13 PM Martin Lau <kafai@fb.com> wrote:
>
> On Wed, Dec 18, 2019 at 02:50:39PM -0800, Andrii Nakryiko wrote:
> > There are cases in which BPF resource (program, map, etc) has to outlive
> > userspace program that "installed" it in the system in the first place.
> > When BPF program is attached, libbpf returns bpf_link object, which
> > is supposed to be destroyed after no longer necessary through
> > bpf_link__destroy() API. Currently, bpf_link destruction causes both automatic
> > detachment and frees up any resources allocated to for bpf_link in-memory
> > representation. This is inconvenient for the case described above because of
> > coupling of detachment and resource freeing.
> >
> > This patch introduces bpf_link__disconnect() API call, which marks bpf_link as
> > disconnected from its underlying BPF resouces. This means that when bpf_link
> > is destroyed later, all its memory resources will be freed, but BPF resource
> > itself won't be detached.
> >
> > This design allows to follow strict and resource-leak-free design by default,
> > while giving easy and straightforward way for user code to opt for keeping BPF
> > resource attached beyond lifetime of a bpf_link. For some BPF programs (i.e.,
> > FS-based tracepoints, kprobes, raw tracepoint, etc), user has to make sure to
> > pin BPF program to prevent kernel to automatically detach it on process exit.
> > This should typically be achived by pinning BPF program (or map in some cases)
> > in BPF FS.
> Thanks for the patch.
>
> Acked-by: Martin KaFai Lau <kafai@fb.com>
Applied. Thanks
prev parent reply other threads:[~2019-12-19 1:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 22:50 [PATCH bpf-next] libbpf: add bpf_link__disconnect() API to preserve underlying BPF resource Andrii Nakryiko
2019-12-18 23:12 ` [Potential Spoof] " Martin Lau
2019-12-19 1:19 ` Alexei Starovoitov [this message]
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