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 9B0052561CC; Wed, 9 Apr 2025 13:29:02 +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=1744205342; cv=none; b=hw8NGdObODfSsODDSQiM3Rsb5RGpbOxtKbM6UrPG/1DbDqhISJhFUrNxeWcizIZWRO9FmsBePEifRvHfYXyanb3Edehme5TGPhKSE1HWBzoBa/glNZRroSpPIj2S1SNfttJpEhc3++zIJGM2qUGJjj/PZqW3JfiV/l3r7LMnKm4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744205342; c=relaxed/simple; bh=Km9/FVRC6jO0f5L6lMq0Nqd/ym5VEVLjWSFCAHLpB/Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sUAdlBOwHkdNL4pzUV7Ld4A7TvqGJRQP7sMiCjXMNNszYmXGOD39J2jQWAaWqHdjBNWSzyYS5tjiGnmSRFRt2tpCYwlG8jPH5ZLeYpmZEnEPwxVKI/dz9CtueqIw0u/FjiMgiTHwyYe33ldF5tTbBPs27Kae498XMrKcg+t32Ag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JaW8AaeG; 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="JaW8AaeG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADBC2C4CEE3; Wed, 9 Apr 2025 13:28:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744205342; bh=Km9/FVRC6jO0f5L6lMq0Nqd/ym5VEVLjWSFCAHLpB/Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JaW8AaeGbE+zWk56+4oZKbLWDEWr5CDoMzsezn52H5jB1+ZmyvcmVxlX7AaUpoRzD 9H49ajkehX5m44qaEY9zQA2csv4ElqHv9DXhIvnBSWTclMAbJVci6hYD5xC5bm/ucH ss6zHFcLZe/eBFir+Moq0F87UgCwRRAqy78tW165dK3Cr7tYZBlOd5z/CQA2MkvMPo 7GgfSU38I8tt66CWw9M0p+50F4Zqb/pTsMSSE89GOhGzkIaz6Nt7Lj3CV0b/4zb/T1 /9y8txxqMmzKMi1IpWjD+bsCziskEXiYSDnvXtXuZ2RNGov53zt5MRlqfZ/ulSCw58 p/oKcvHYry7JQ== Message-ID: Date: Wed, 9 Apr 2025 15:28:55 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next V2 2/2] net: sched: generalize check for no-op qdisc To: Eric Dumazet , netdev@vger.kernel.org, Jakub Kicinski , edumazet@google.com Cc: bpf@vger.kernel.org, tom@herbertland.com, "David S. Miller" , Paolo Abeni , =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , dsahern@kernel.org, makita.toshiaki@lab.ntt.co.jp, kernel-team@cloudflare.com References: <174412623473.3702169.4235683143719614624.stgit@firesoul> <174412628464.3702169.81132659219041209.stgit@firesoul> <1ad134d3-4173-4d43-b2ad-0b2c5165bbc1@gmail.com> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <1ad134d3-4173-4d43-b2ad-0b2c5165bbc1@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 08/04/2025 17.47, Eric Dumazet wrote: > > On 4/8/25 5:31 PM, Jesper Dangaard Brouer wrote: >> Several drivers (e.g., veth, vrf) contain open-coded checks to determine >> whether a TX queue has a real qdisc attached - typically by testing if >> qdisc->enqueue is non-NULL. >> >> These checks are functionally equivalent to comparing the queue's qdisc >> pointer against &noop_qdisc (qdisc named "noqueue"). This equivalence >> stems from noqueue_init(), which explicitly clears the enqueue pointer >> for the "noqueue" qdisc. As a result, __dev_queue_xmit() treats the qdisc >> as a no-op only when enqueue == NULL. >> >> This patch introduces a common helper, qdisc_txq_is_noop() to standardize >> this check. The helper is added in sch_generic.h and replaces open-coded >> logic in both the veth and vrf drivers. >> >> This is a non-functional change. >> >> Signed-off-by: Jesper Dangaard Brouer >> --- >>   drivers/net/veth.c        |   14 +------------- >>   drivers/net/vrf.c         |    3 +-- >>   include/net/sch_generic.h |    7 ++++++- >>   3 files changed, 8 insertions(+), 16 deletions(-) >> >> diff --git a/drivers/net/veth.c b/drivers/net/veth.c >> index f29a0db2ba36..83c7758534da 100644 >> --- a/drivers/net/veth.c >> +++ b/drivers/net/veth.c >> @@ -341,18 +341,6 @@ static bool veth_skb_is_eligible_for_gro(const >> struct net_device *dev, >>            rcv->features & (NETIF_F_GRO_FRAGLIST | NETIF_F_GRO_UDP_FWD)); >>   } >> -/* Does specific txq have a real qdisc attached? - see noqueue_init() */ >> -static inline bool txq_has_qdisc(struct netdev_queue *txq) >> -{ >> -    struct Qdisc *q; >> - >> -    q = rcu_dereference(txq->qdisc); >> -    if (q->enqueue) >> -        return true; >> -    else >> -        return false; >> -} >> - >>   static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device >> *dev) >>   { >>       struct veth_priv *rcv_priv, *priv = netdev_priv(dev); >> @@ -399,7 +387,7 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, >> struct net_device *dev) >>            */ >>           txq = netdev_get_tx_queue(dev, rxq); >> -        if (!txq_has_qdisc(txq)) { >> +        if (qdisc_txq_is_noop(txq)) { >>               dev_kfree_skb_any(skb); >>               goto drop; >>           } >> diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c >> index 7168b33adadb..d4fe36c55f29 100644 >> --- a/drivers/net/vrf.c >> +++ b/drivers/net/vrf.c >> @@ -349,9 +349,8 @@ static bool qdisc_tx_is_default(const struct >> net_device *dev) >>           return false; >>       txq = netdev_get_tx_queue(dev, 0); >> -    qdisc = rcu_access_pointer(txq->qdisc); >> -    return !qdisc->enqueue; >> +    return qdisc_txq_is_noop(txq); >>   } >>   /* Local traffic destined to local address. Reinsert the packet to rx >> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h >> index d48c657191cd..eb90d5103371 100644 >> --- a/include/net/sch_generic.h >> +++ b/include/net/sch_generic.h >> @@ -803,6 +803,11 @@ static inline bool qdisc_tx_changing(const struct >> net_device *dev) >>       return false; >>   } >> +static inline bool qdisc_txq_is_noop(const struct netdev_queue *txq) >> +{ >> +    return (rcu_access_pointer(txq->qdisc) == &noop_qdisc); > > > return (expression); > > -> > > return expression; > > > return rcu_access_pointer(txq->qdisc) == &noop_qdisc; Will fix in next iteration. > I also feel this patch should come first in the series ? > To me it looks/feels wrong doing this before there are two users. With only the vrf driver, the changed looked unnecessary. The diff stats looks/feels wrong, when it's patch-1. As I have to respin anyhow, I will let you decide. Please let me know, if you prefer this to be patch-1 ? --Jesper