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[209.85.208.176]) by smtp.gmail.com with ESMTPSA id m10sm60502lji.72.2020.07.02.20.34.33 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 02 Jul 2020 20:34:33 -0700 (PDT) Received: by mail-lj1-f176.google.com with SMTP id z24so10191347ljn.8 for ; Thu, 02 Jul 2020 20:34:33 -0700 (PDT) X-Received: by 2002:a05:651c:1b6:: with SMTP id c22mr15442024ljn.421.1593747272949; Thu, 02 Jul 2020 20:34:32 -0700 (PDT) MIME-Version: 1.0 References: <20200702200329.83224-1-alexei.starovoitov@gmail.com> <20200702200329.83224-4-alexei.starovoitov@gmail.com> <20200703023547.qpu74obn45qvb2k7@ast-mbp.dhcp.thefacebook.com> In-Reply-To: <20200703023547.qpu74obn45qvb2k7@ast-mbp.dhcp.thefacebook.com> From: Linus Torvalds Date: Thu, 2 Jul 2020 20:34:17 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH bpf-next 3/3] bpf: Add kernel module with user mode driver that populates bpffs. To: Alexei Starovoitov Cc: David Miller , Daniel Borkmann , "Eric W. Biederman" , Netdev , bpf , kernel-team@fb.com Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Jul 2, 2020 at 7:35 PM Alexei Starovoitov wrote: > > On Thu, Jul 02, 2020 at 06:05:29PM -0700, Linus Torvalds wrote: > > On Thu, Jul 2, 2020 at 1:03 PM Alexei Starovoitov > > wrote: > > > > > > The BPF program dump_bpf_prog() in iterators.bpf.c is printing this data about > > > all BPF programs currently loaded in the system. This information is unstable > > > and will change from kernel to kernel. > > > > If so, it should probably be in debugfs, not in /sys/fs/ > > /sys/fs/bpf/ is just a historic location where we chose to mount bpffs. It's more the "information is unstable and will change from kernel to kernel" No such interfaces exist. If people start parsing it and depending it, it's suddenly an ABI, whether you want to or not (and whether you documented it or not). At least if it's in /sys/kernel/debug/bpf/ or something, it's less likely that anybody will do that. Linus