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Thu, 15 Oct 2026 19:12:40 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Fri, 16 Oct 2026 02:12:39 +0000 Message-Id: To: "Yonghong Song" , Cc: "Andrii Nakryiko" , "Daniel Borkmann" , "Eduard Zingerman" , Subject: Re: [PATCH bpf-next v11 13/26] bpf: Allow a subprog to end with a call that does not return From: "Alexei Starovoitov" In-Reply-To: <20261015040250.860960-1-yonghong.song@linux.dev> References: <20261015040143.854070-1-yonghong.song@linux.dev> <20261015040250.860960-1-yonghong.song@linux.dev> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, Oct 14, 2026 at 09:02 PM Yonghong Song wrote: > Let a call to a subprog or to a kfunc be the last insn of a subprog, and > give it no fall-through edge in the CFG walk or in bpf_insn_successors(). [...] > include/linux/bpf_verifier.h | 10 +++++ > kernel/bpf/backtrack.c | 6 ++- > kernel/bpf/cfg.c | 5 +++ > kernel/bpf/liveness.c | 9 ++--- > kernel/bpf/verifier.c | 74 ++++++++++++++++++++++++++++++------ > 5 files changed, 85 insertions(+), 19 deletions(-) This is quite heavy. keep_subprog_exits() in the previous patch adds 'exit' after the last insn with bpf_patch_insn_data(). Can we do the same for a subprog that ends with a call before bpf_check_cfg() ? Then cfg, liveness, backtracking, fastcall and prepare_func_exit() don't need to know about it. Only the check_subprogs() hunk stays.