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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RiCyPstA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RiCyPstA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F247C4CECD; Sun, 10 Nov 2024 04:32:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731213139; bh=wRsKypjP2OByLYsA+M0pb5KAA7Cb6OFKBAXcyvFE4fY=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=RiCyPstAEt3wZMaDvGNneNBwIs1K7mTGZxmjm/dXN94dgonz3KrnWp/o6403kaaD+ +r8CBtzBjPq9SMj7hYMr6D241OlOfCeB9RDO3ZYrtDcbptD1KSHvmT7cpX35BQsT6o eUZObnWUnsI0Q2AZbRFplU/rAQJv1OcLii/HWM5t3teftDGvw+kiqoZQO9PmVkhqk1 5rd9KVJ9he0EYKTMKuA1/j3uLXDyg87SDuofLp3xKH9q57OBzp6qRULMqyDaNdpbQ9 BmsbbQInM6JuzyeijlRY58V0Aku4HNIyPoimrfRoI5oqj3y3Q+OT15qirBILvsD6NN Q2cSwEL73fXXg== Message-ID: <99efee88657d30fd4471376bd628cc913654fd50.camel@kernel.org> Subject: Re: [PATCH mptcp-next v2 23/36] mptcp: drop struct mptcp_pm_local From: Geliang Tang To: Matthieu Baerts , mptcp@lists.linux.dev Cc: Geliang Tang Date: Sun, 10 Nov 2024 12:32:15 +0800 In-Reply-To: <2a8bb3262f35643316090550ecba249da42d1e5e.camel@kernel.org> References: <5b8a8e318c9d661f495b6d0be2b7a776de7da7a1.1729588019.git.tanggeliang@kylinos.cn> <4661b240-9a9c-47c2-9dc0-362d22baad83@kernel.org> <2a8bb3262f35643316090550ecba249da42d1e5e.camel@kernel.org> Autocrypt: addr=geliang@kernel.org; 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charset="UTF-8" User-Agent: Evolution 3.54.0-1 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Matt, On Thu, 2024-11-07 at 18:19 +0800, Geliang Tang wrote: > Hi Matt, > > On Thu, 2024-11-07 at 11:00 +0100, Matthieu Baerts wrote: > > Hi Geliang, > > > > On 07/11/2024 08:29, Geliang Tang wrote: > > > Hi Matt, > > > > > > On Mon, 2024-11-04 at 20:08 +0100, Matthieu Baerts wrote: > > > > Hi Geliang, > > > > > > > > On 22/10/2024 11:14, Geliang Tang wrote: > > > > > From: Geliang Tang > > > > > > > > > > The following code in mptcp_pm_nl_subflow_create_doit() that > > > > > assigns struct > > > > > mptcp_pm_addr_entry "entry" to the local struct > > > > > mptcp_pm_local > > > > > variable > > > > > "local" is not allowed in BPF if we use the same code to > > > > > implement > > > > > the > > > > > subflow_create() interface of a BFP path manager: > > > > > > > > > > struct mptcp_pm_local local; > > > > > > > > > > local.addr = entry.addr; > > > > > local.flags = entry.flags; > > > > > local.ifindex = entry.ifindex; > > > > > > > > Here as well, I'm not sure to understand the issue. Is it > > > > because > > > > you > > > > cannot allocate this structure locally with BPF? No > > > > alternatives? > > > > > > Here "struct mptcp_pm_local local" is a "scalar", when passing it > > > to > > > __mptcp_subflow_connect(), this error occurs: > > > > > > # ; err = __mptcp_subflow_connect(sk, &local, remote); @ > > > mptcp_bpf_userspace_pm.c:242 > > > # 53: (bf) r1 = r6                      ; > > > R1_w=trusted_ptr_mptcp_sock() > > > R6=trusted_ptr_mptcp_sock() > > > # 54: (bf) r3 = r8                      ; > > > R3_w=trusted_ptr_mptcp_addr_info() > > > R8=trusted_ptr_mptcp_addr_info() > > > # 55: (85) call __mptcp_subflow_connect#34404 > > > # max struct nesting depth exceeded > > > # arg#1 pointer type STRUCT mptcp_pm_local must point to scalar, > > > or > > > struct with scalar > > > > > > Also, assigning an address to an address like this is not allowed > > > in > > > BPF: > > > > > > local.addr = entry.addr; > > > > OK, thank you, that's a bit clearer (even if it is not clear what > > BPF > > code was causing that). For this kind of issue, would it work to > > add > > a > > BPF-specific kfunc, eventually with additional annotations or > > arguments, > > or taking a "struct mptcp_pm_addr_entry" in argument, and "simply" > > calling __mptcp_subflow_connect() with a "struct mptcp_pm_local"? > > It works indeed. But I prefer the version in v3, "mptcp: use > mptcp_pm_local in pm_netlink only". It makes more sense to move > mptcp_pm_local in pm_netlink.c. I thought about it again and felt that "mptcp: use mptcp_pm_local in pm_netlink only" was not a good solution. If we want to add fullmesh support to userspace pm in the future, we also need to use struct mptcp_pm_local in pm_netlink.c. So I decided to deprecate "mptcp: use mptcp_pm_local in pm_netlink only" and keep the code for struct mptcp_pm_local as it is. As you suggested, add a BPF-specific kfunc to solve the issue. Thanks, -Geliang > > WDYT? > > Thanks, > -Geliang > > > > > So something specific to BPF, without impacting the rest? > > > > Cheers, > > Matt > >