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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a59e001305sm10841718a12.4.2026.08.24.13.09.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Aug 2026 13:09:54 -0700 (PDT) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 24 Aug 2026 22:09:52 +0200 Message-Id: To: "Jakub Kicinski" , Cc: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v8 net-next 0/2] Explicit TSO segment count From: "Kumar Kartikeya Dwivedi" X-Mailer: aerc 0.21.0 References: <20260824163139.990734-1-chia-yu.chang@nokia-bell-labs.com> <20260824130511.2955f30d@kernel.org> In-Reply-To: <20260824130511.2955f30d@kernel.org> On Mon Aug 24, 2026 at 10:05 PM CEST, Jakub Kicinski wrote: > On Mon, 24 Aug 2026 18:31:37 +0200 chia-yu.chang@nokia-bell-labs.com > wrote: >> From: Chia-Yu Chang >> >> Hello, >> >> This series replaces the existing min_tso_segs() congestion control >> callback with a new tso_segs() callback that allows congestion control >> algorithms to provide an explicit TSO segment count for each data burst. >> =C2=A0 >> To support BPF congestion controls, the series also exposes >> tcp_tso_autosize() as a BPF kfunc, allowing BPF implementations to >> reuse the kernel TSO autosizing logic while implementing custom >> tso_segs() callbacks. > > AI CI says: > > The bpf-ci build jobs are failing for this patch on all tested > architectures/toolchains (x86-64 gcc-15, x86-64 llvm-21, aarch64 gcc-15, > s390x gcc-15), all with the same link-time error: > > net/ipv4/tcp_bbr.o: in function `__BTF_ID__set8__tcp_bbr_check_kfunc_id= s': > tcp_bbr.c:(.BTF_ids+0x...): undefined reference to `KF_DEPRECATED' > > This comes from the change to net/ipv4/tcp_bbr.c that marks the retained > bbr_min_tso_segs() kfunc entry with the KF_DEPRECATED flag: > > BTF_ID_FLAGS(func, bbr_min_tso_segs, KF_DEPRECATED) > BTF_ID_FLAGS(func, bbr_tso_segs) > > KF_DEPRECATED does not resolve to a usable symbol/flag in this tree, so > the BTF id set for tcp_bbr fails to link into vmlinux on every > architecture and toolchain -- it's a straight undefined-reference error, > not a per-arch/per-config issue. > > Could you drop the KF_DEPRECATED flag (or use a flag that this kfunc > infrastructure actually defines) on bbr_min_tso_segs, and re-verify that > the kernel links cleanly? A local `make net/ipv4/tcp_bbr.o vmlinux` > build (or the bpf-ci selftest build job) should reproduce this quickly. > > Full build log for reference: > > ld.lld-21: error: undefined symbol: KF_DEPRECATED > >>> referenced by usercopy_64.c > >>> vmlinux.o:(__BTF_ID__set8__tcp_bbr_check_kfunc_ids) I think Chia-Yu's AI is hallucinating, it was a proposed flag but not added= yet...