From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F46E381AF for ; Thu, 23 Jan 2025 11:37:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737632226; cv=none; b=ppdlobN4BAMIXHx7GzmlPsbd0H0KMVs3Ex3WpIc5y5S0D2T7rOSCgvBLtE4YRl84GqlE/fXg5LgEeC6o2AeTJXyp7SddMHuihG8U8Dmo0lfybbM2kBdkG+dcutlPE/6HvrpHQ11KeJsPuh5R+PjTsrycfuFcl1Fjs2lDIWGsHb8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737632226; c=relaxed/simple; bh=CAS5qzh93qxx/xh2YnoScvvnQxj8YRyL7CNquZH/RI8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FT9ooF8xt/FUObi9o1cA8uYgq8Xzrk1xHgLOwvx+XdmbzbF5Y+MC2X/Oq1tnvkC8DMNh4op1mRaMdX+rBRaWPgRJmJNu/41Cs8eI1uS3xCiKcvSOj0sFZvT9TAoiXTFyRxvh62iwvxfLYi0GibeDlqzD5d5ngZT2xfCGvDa3ckM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hECV0VRH; 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="hECV0VRH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDD6FC4CED3; Thu, 23 Jan 2025 11:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737632225; bh=CAS5qzh93qxx/xh2YnoScvvnQxj8YRyL7CNquZH/RI8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hECV0VRHu1vIM7T+Sy0FhhShZB+GVQ/42d0mdpYN3N5xvnf/aIsF0R9p2eVk1B1lg BpKNJb0s0kLE4fMBE1s4VIPtSMoy9oL1eQPpLTQVHjcPnUsx/Etl4k1MyzSfrKsJpy KaVI3hyEi9Y4mK34B0ti5N34CTQHaQy/B7GoaEXSvIeddsfBdLTw25fBiUOlYbznQL QSk4KqnDPBWwN5Et8MYEAtG8jxATMOUtgfrHbyHu8Cb557B0GOE58Bd3gUiLOcKAgj 7Ix56UN1c7waFhO84E7M42LaETnWLmEBsU56OvaNQtR7DofgWouHM8YP+9ufqVHqD7 KItL3W6B0nuQw== Message-ID: Date: Thu, 23 Jan 2025 12:37:02 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-next v4 1/7] mptcp: add mptcp_pm_genl_fill_addr helper Content-Language: en-GB To: Geliang Tang , mptcp@lists.linux.dev Cc: Geliang Tang References: From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Geliang, On 16/01/2025 08:26, Geliang Tang wrote: > From: Geliang Tang > > To save some redundant code in dump_addr() interfaces of both the > netlink PM and userspace PM, the code that calls netlink message > helpers (genlmsg_put/cancel/end) and mptcp_nl_fill_addr() is wrapped > into a new helper mptcp_pm_genl_fill_addr(). I'm OK with the suggested modification here below (just one small detail, please see below), but ... > This helper will also be used in BPF path managers. ... that doesn't sound right: I don't see why a BPF PM has to dump addresses via Netlink. In your cover-letter, you mentioned the dump_addr() will not be implemented in the BPF PM, so I guess you left this line by accident, right? If not: with the in-kernel PM, it is needed to dump the endpoints to know what has been set. With the userspace PM, the dump is useful for a userspace PM daemon to recover from a restart. For these two PM, Netlink is used between the userspace and the kernelspace, so that makes sense to continue to do so. With the BPF PM, I don't really see the point: all the communication (configuration, status, decisions, etc.) should be done via BPF, no? (...) > diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c > index fef01692eaed..afd517ff260c 100644 > --- a/net/mptcp/pm_netlink.c > +++ b/net/mptcp/pm_netlink.c > @@ -1798,7 +1798,6 @@ int mptcp_pm_nl_dump_addr(struct sk_buff *msg, > struct mptcp_pm_addr_entry *entry; > struct pm_nl_pernet *pernet; > int id = cb->args[0]; > - void *hdr; > int i; > > pernet = pm_nl_get_pernet(net); > @@ -1813,19 +1812,10 @@ int mptcp_pm_nl_dump_addr(struct sk_buff *msg, > if (entry->addr.id <= id) > continue; > > - hdr = genlmsg_put(msg, NETLINK_CB(cb->skb).portid, > - cb->nlh->nlmsg_seq, &mptcp_genl_family, > - NLM_F_MULTI, MPTCP_PM_CMD_GET_ADDR); > - if (!hdr) > + if (mptcp_pm_genl_fill_addr(msg, cb, entry)) Even if technically, it is correct, it feels "strange" to see: if (foo()) /* error path */ It feels a bit like having: if (success()) /* error */ If the goal is to stop in case of error, better being explicit about that: if (foo() < 0) /* error path */ > break; > > - if (mptcp_nl_fill_addr(msg, entry) < 0) { > - genlmsg_cancel(msg, hdr); > - break; > - } > - > id = entry->addr.id; > - genlmsg_end(msg, hdr); > } > } > rcu_read_unlock(); > diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c > index 277cf092a870..b50462b527bd 100644 > --- a/net/mptcp/pm_userspace.c > +++ b/net/mptcp/pm_userspace.c > @@ -641,7 +641,6 @@ int mptcp_userspace_pm_dump_addr(struct sk_buff *msg, > struct mptcp_sock *msk; > int ret = -EINVAL; > struct sock *sk; > - void *hdr; > > bitmap = (struct id_bitmap *)cb->ctx; > > @@ -657,19 +656,10 @@ int mptcp_userspace_pm_dump_addr(struct sk_buff *msg, > if (test_bit(entry->addr.id, bitmap->map)) > continue; > > - hdr = genlmsg_put(msg, NETLINK_CB(cb->skb).portid, > - cb->nlh->nlmsg_seq, &mptcp_genl_family, > - NLM_F_MULTI, MPTCP_PM_CMD_GET_ADDR); > - if (!hdr) > + if (mptcp_pm_genl_fill_addr(msg, cb, entry)) Same here: < 0 > break; > > - if (mptcp_nl_fill_addr(msg, entry) < 0) { > - genlmsg_cancel(msg, hdr); > - break; > - } > - > __set_bit(entry->addr.id, bitmap->map); > - genlmsg_end(msg, hdr); > } > spin_unlock_bh(&msk->pm.lock); > release_sock(sk); (...) Cheers, Matt -- Sponsored by the NGI0 Core fund.