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Date: Wed, 23 Jul 2025 17:30:38 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Jakub Sitnicki <jakub@cloudflare.com>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>, Andrii
 Nakryiko <andrii@kernel.org>, Arthur Fabre <arthur@arthurfabre.com>, Daniel
 Borkmann <daniel@iogearbox.net>, Eduard Zingerman <eddyz87@gmail.com>, Eric
 Dumazet <edumazet@google.com>, Jesper Dangaard Brouer <hawk@kernel.org>,
 Jesse Brandeburg <jbrandeburg@cloudflare.com>, Joanne Koong
 <joannelkoong@gmail.com>, Lorenzo Bianconi <lorenzo@kernel.org>, Martin
 KaFai Lau <martin.lau@linux.dev>, Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNl?=
 =?UTF-8?B?bg==?= <thoiland@redhat.com>, Yan Zhai <yan@cloudflare.com>,
 kernel-team@cloudflare.com, netdev@vger.kernel.org, Stanislav Fomichev
 <sdf@fomichev.me>
Subject: Re: [PATCH bpf-next v4 2/8] bpf: Enable read/write access to skb
 metadata through a dynptr
Message-ID: <20250723173038.45cbaf01@kernel.org>
In-Reply-To: <20250723-skb-metadata-thru-dynptr-v4-2-a0fed48bcd37@cloudflare.com>
References: <20250723-skb-metadata-thru-dynptr-v4-0-a0fed48bcd37@cloudflare.com>
	<20250723-skb-metadata-thru-dynptr-v4-2-a0fed48bcd37@cloudflare.com>
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On Wed, 23 Jul 2025 19:36:47 +0200 Jakub Sitnicki wrote:
> Now that we can create a dynptr to skb metadata, make reads to the metadata
> area possible with bpf_dynptr_read() or through a bpf_dynptr_slice(), and
> make writes to the metadata area possible with bpf_dynptr_write() or
> through a bpf_dynptr_slice_rdwr().

What are the expectations around the writes? Presumably we could have
two programs writing into the same metadata if the SKB is a clone, no?