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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4310adeee0esm5728364f8f.29.2025.12.17.08.27.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 08:27:58 -0800 (PST) From: =?UTF-8?q?Michal=20Koutn=C3=BD?= To: linux-block@vger.kernel.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, coreteam@netfilter.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Cc: =?UTF-8?q?Michal=20Koutn=C3=BD?= , Hao Luo , Mathieu Desnoyers , Alexei Starovoitov , Phil Sutter , Yonghong Song , Jens Axboe , Jozsef Kadlecsik , Steven Rostedt , Martin KaFai Lau , KP Singh , Eric Dumazet , Florian Westphal , Jiri Olsa , Stanislav Fomichev , Song Liu , "David S. Miller" , Simon Horman , John Fastabend , Johannes Weiner , Daniel Borkmann , Andrii Nakryiko , Tejun Heo , Josef Bacik , Paolo Abeni , "Gustavo A. R. Silva" , Pablo Neira Ayuso , Eduard Zingerman , Yu Kuai , Masami Hiramatsu , Kees Cook , Jakub Kicinski Subject: [PATCH 0/4] Use __counted_by for ancestor arrays Date: Wed, 17 Dec 2025 17:27:32 +0100 Message-ID: <20251217162744.352391-1-mkoutny@suse.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The trick with utilizing space in cgroup_root for cgroup::ancetors flex array was an obstacle for kernel reworks for -Wflex-array-member-not-at-end. The first patch fixes that, then I wanted to utilize __counted_by for this flex array which required some more rework how cgroup level is evaluated. Similar flex array is also in struct ioc_gq where it was tempting to simply use __counted_by(level), however, this would be off-by-one as it has semantics like cgroup's level (0 == root). Proper adjustment for __counted_by() would either need similar level/ancestor helpers or abstracted macros for ancestors up/down iterations. I only made a simple comment fixup since I'm not sure about benefit of __counted_by for structs that aren't sized based on direct user input. Michal Koutný (4): cgroup: Eliminate cgrp_ancestor_storage in cgroup_root cgroup: Introduce cgroup_level() helper cgroup: Use __counted_by for cgroup::ancestors blk-iocost: Correct comment ioc_gq::level block/bfq-iosched.c | 2 +- block/blk-iocost.c | 6 ++--- include/linux/cgroup-defs.h | 43 +++++++++++++++++++---------------- include/linux/cgroup.h | 18 ++++++++++++--- include/trace/events/cgroup.h | 8 +++---- kernel/bpf/helpers.c | 2 +- kernel/cgroup/cgroup.c | 9 ++++---- net/netfilter/nft_socket.c | 2 +- 8 files changed, 53 insertions(+), 37 deletions(-) base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8 -- 2.52.0