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([2620:10d:c090:500::1:11ba]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30c7ca8b918sm22125081eec.28.2026.06.26.11.52.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Jun 2026 11:52:08 -0700 (PDT) Message-ID: Subject: Re: [PATCH bpf-next v2 01/15] bpf: Remove __rcu tagging in st_link->map From: Eduard Zingerman To: Amery Hung , bpf@vger.kernel.org Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, memxor@gmail.com, martin.lau@kernel.org, shakeel.butt@linux.dev, roman.gushchin@linux.dev, kuniyu@google.com, kerneljasonxing@gmail.com, kernel-team@meta.com Date: Fri, 26 Jun 2026 11:52:06 -0700 In-Reply-To: <20260623175006.3136053-2-ameryhung@gmail.com> References: <20260623175006.3136053-1-ameryhung@gmail.com> <20260623175006.3136053-2-ameryhung@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (3.60.1-1.fc44) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-06-23 at 10:49 -0700, Amery Hung wrote: > From: Martin KaFai Lau >=20 > st_link->map is always written under update_mutex. The paths that read > st_link->map with rcu_read_lock() are not in the fast path, so they can > simply take update_mutex instead. Remove the __rcu annotation and replace > all RCU accessors with direct pointer reads under update_mutex. Use > READ_ONCE() in bpf_struct_ops_map_link_poll() which reads the pointer > without holding update_mutex. >=20 > It is a simplification change. >=20 > Signed-off-by: Martin KaFai Lau > Signed-off-by: Amery Hung > --- Reviewed-by: Eduard Zingerman [...]