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[79.184.124.63]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b935ab13558sm914137766b.5.2026.03.05.02.40.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Mar 2026 02:40:28 -0800 (PST) From: Jakub Sitnicki To: Keita Morisaki Cc: Eric Dumazet , Neal Cardwell , "David S . Miller" , David Ahern , Jakub Kicinski , Paolo Abeni , Kuniyuki Iwashima , Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] tcp: remove unused hash_size from struct tcp_out_options In-Reply-To: <20260305022703.3946470-1-kmta1236@gmail.com> (Keita Morisaki's message of "Thu, 5 Mar 2026 11:27:03 +0900") References: <20260305022703.3946470-1-kmta1236@gmail.com> Date: Thu, 05 Mar 2026 11:40:27 +0100 Message-ID: <87eclyo8ys.fsf@cloudflare.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Mar 05, 2026 at 11:27 AM +09, Keita Morisaki wrote: > hash_size is declared but never read. The MD5 path always uses a > fixed size of 16, and the TCP-AO path uses tcp_ao_maclen(). > > Suggested-by: Jakub Sitnicki > Signed-off-by: Keita Morisaki > --- > net/ipv4/tcp_output.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > index 63ee037f46e50..f0e04ebd8b723 100644 > --- a/net/ipv4/tcp_output.c > +++ b/net/ipv4/tcp_output.c > @@ -441,7 +441,6 @@ struct tcp_out_options { > u8 ws; /* window scale, 0 to disable */ > u8 num_accecn_fields:7, /* number of AccECN fields needed */ > use_synack_ecn_bytes:1; /* Use synack_ecn_bytes or not */ > - u8 hash_size; /* bytes in hash_location */ > __u8 *hash_location; /* temporary pointer, overloaded */ > __u32 tsval, tsecr; /* need to include OPTION_TS */ > struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ > > base-commit: 21fc6b53f12379f3f9b29830be3597a322261df8 Worth noting that this closes a 7-byte hole we had there: u8 num_accecn_fields:7; /* 7: 0 1 */ u8 use_synack_ecn_bytes:1; /* 7: 7 1 */ u8 hash_size; /* 8 1 */ /* XXX 7 bytes hole, try to pack */ __u8 * hash_location; /* 16 8 */ Struct size went down from 96B to 88B.