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[34.85.207.234]) by smtp.gmail.com with UTF8SMTPSA id 00721157ae682-71665b43cbcsm12664257b3.109.2025.07.06.10.15.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Jul 2025 10:15:07 -0700 (PDT) Date: Sun, 06 Jul 2025 13:15:06 -0400 From: Willem de Bruijn To: Willem de Bruijn , Daniel Zahka , Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Jonathan Corbet , Andrew Lunn Cc: Saeed Mahameed , Leon Romanovsky , Tariq Toukan , Boris Pismenny , Kuniyuki Iwashima , Willem de Bruijn , David Ahern , Neal Cardwell , Patrisious Haddad , Raed Salem , Jianbo Liu , Dragos Tatulea , Rahul Rameshbabu , Stanislav Fomichev , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , Alexander Lobakin , Jacob Keller , netdev@vger.kernel.org Message-ID: <686aaf1acacc1_3b7462294aa@willemb.c.googlers.com.notmuch> In-Reply-To: <686aa91268bbd_3ad0f32942b@willemb.c.googlers.com.notmuch> References: <20250702171326.3265825-1-daniel.zahka@gmail.com> <20250702171326.3265825-10-daniel.zahka@gmail.com> <686aa91268bbd_3ad0f32942b@willemb.c.googlers.com.notmuch> Subject: Re: [PATCH v3 09/19] net: psp: update the TCP MSS to reflect PSP packet overhead Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Willem de Bruijn wrote: > Daniel Zahka wrote: > > From: Jakub Kicinski > > > > PSP eats 32B of header space. Adjust MSS appropriately. > > > > We can either modify tcp_mtu_to_mss() / tcp_mss_to_mtu() > > or reuse icsk_ext_hdr_len. The former option is more TCP > > specific and has runtime overhead. The latter is a bit > > of a hack as PSP is not an ext_hdr. If one squints hard > > enough, UDP encap is just a more practical version of > > IPv6 exthdr, so go with the latter. Happy to change. > > > > Signed-off-by: Jakub Kicinski > > Signed-off-by: Daniel Zahka > > --- > > > > Notes: > > v1: > > - https://lore.kernel.org/netdev/20240510030435.120935-8-kuba@kernel.org/ > > > > include/net/psp/functions.h | 12 ++++++++++++ > > include/net/psp/types.h | 3 +++ > > net/ipv4/tcp_ipv4.c | 4 ++-- > > net/ipv6/ipv6_sockglue.c | 6 +++++- > > net/ipv6/tcp_ipv6.c | 6 +++--- > > net/psp/psp_sock.c | 5 +++++ > > 6 files changed, 30 insertions(+), 6 deletions(-) > > > > > @@ -95,6 +95,9 @@ struct psp_dev_caps { > > #define PSP_V1_KEY 32 > > #define PSP_MAX_KEY 32 > > > > +#define PSP_HDR_SIZE 16 /* We don't support optional fields, yet */ > > Duplicate of PSP_HDRLEN_NOOPT? Oh no it is not: that is the length in 64b words.