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Thu, 27 Feb 2025 01:53:55 -0800 (PST) Received: from cloudflare.com ([2a09:bac5:506a:2dc::49:df]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5e4c3fb58f7sm826692a12.57.2025.02.27.01.53.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2025 01:53:54 -0800 (PST) From: Jakub Sitnicki To: Cong Wang Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, john.fastabend@gmail.com, zhoufeng.zf@bytedance.com, zijianzhang@bytedance.com, Cong Wang Subject: Re: [Patch bpf-next 3/4] skmsg: use bitfields for struct sk_psock In-Reply-To: (Cong Wang's message of "Wed, 26 Feb 2025 14:21:52 -0800") References: <20250222183057.800800-1-xiyou.wangcong@gmail.com> <20250222183057.800800-4-xiyou.wangcong@gmail.com> <87ldtsu882.fsf@cloudflare.com> Date: Thu, 27 Feb 2025 10:53:53 +0100 Message-ID: <87eczju30u.fsf@cloudflare.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed, Feb 26, 2025 at 02:21 PM -08, Cong Wang wrote: > On Wed, Feb 26, 2025 at 02:49:17PM +0100, Jakub Sitnicki wrote: >> On Sat, Feb 22, 2025 at 10:30 AM -08, Cong Wang wrote: >> > From: Cong Wang >> > >> > psock->eval can only have 4 possible values, make it 8-bit is >> > sufficient. >> > >> > psock->redir_ingress is just a boolean, using 1 bit is enough. >> > >> > Signed-off-by: Cong Wang >> > --- >> > include/linux/skmsg.h | 4 ++-- >> > 1 file changed, 2 insertions(+), 2 deletions(-) >> > >> > diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h >> > index bf28ce9b5fdb..beaf79b2b68b 100644 >> > --- a/include/linux/skmsg.h >> > +++ b/include/linux/skmsg.h >> > @@ -85,8 +85,8 @@ struct sk_psock { >> > struct sock *sk_redir; >> > u32 apply_bytes; >> > u32 cork_bytes; >> > - u32 eval; >> > - bool redir_ingress; /* undefined if sk_redir is null */ >> > + unsigned int eval : 8; >> > + unsigned int redir_ingress : 1; /* undefined if sk_redir is null */ >> > struct sk_msg *cork; >> > struct sk_psock_progs progs; >> > #if IS_ENABLED(CONFIG_BPF_STREAM_PARSER) >> >> Are you doing this bit packing to create a hole big enough to fit >> another u32 introduced in the next patch? > > Kinda, or at least trying to save some space for the next patch. I am > not yet trying to reorder them to make it more packed, because it can > be a separate patch. OK. Asking because the intention is not expressed in the description. Nit: Why the switch to an implicitly sized integer type? It feels a bit silly when you can just declare an `u8 eval`.