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 7C058349AE0; Wed, 3 Dec 2025 16:49:57 +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=1764780597; cv=none; b=F2/KpqGN1kIIcOn3QTvE7DbKmg/JVQI0z3y7Y57u/RlcXBDk+7ypKJZKWuNplB/4mWDcC10DxpKS6kQjxe06tITKl6poEbwCM17O9dTQ+YxSnnL+ABsCogOgg0lSKEAsP05IqGZNxXdBkgGn/bvmx0xZIOB+JkTRn6lvPMmdvaw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764780597; c=relaxed/simple; bh=oICig/v+ikYFpAJeZ7QZktP7cMngW8eOoMdyjiQUxFU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=JQxlytcR8yBgOjp5hOmlK1p/DxdSK4XMycScVGtAW4kd9ICnZzcGo2XMfGaufmsYdQpgZwkMfDO7YXbqvuqJ2JAniVuOuC1qoKXwqk+l3zDhU5ryNRJG6ye59BC719aFZtlEcypMicEc6D6mDbwgHtBUL9rphBWQTBgVeZ5tyNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GKRx2dax; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="GKRx2dax" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03663C4CEF5; Wed, 3 Dec 2025 16:49:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764780597; bh=oICig/v+ikYFpAJeZ7QZktP7cMngW8eOoMdyjiQUxFU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GKRx2daxGHbnXTVq5WLPc0T+9ecUlNeV6mgsXHCbiANIZlmI8dvSpw0Pvgk+t7AU6 WUOu8D5vZw03PzpW47GEK2pdVSnrHGnvHov44ApYPnrjGuoobwm0ItEVvSjy9iqyKw DzbGf4pe2IfXnb0xIz2jn60AUMuSOlxZn9fYEuRA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Ahern , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Jesper Dangaard Brouer , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 009/132] net: sched: generalize check for no-queue qdisc on TX queue Date: Wed, 3 Dec 2025 16:28:08 +0100 Message-ID: <20251203152343.637307392@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251203152343.285859633@linuxfoundation.org> References: <20251203152343.285859633@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jesper Dangaard Brouer [ Upstream commit 34dd0fecaa02d654c447d43a7e4c72f9b18b7033 ] The "noqueue" qdisc can either be directly attached, or get default attached if net_device priv_flags has IFF_NO_QUEUE. In both cases, the allocated Qdisc structure gets it's enqueue function pointer reset to NULL by noqueue_init() via noqueue_qdisc_ops. This is a common case for software virtual net_devices. For these devices with no-queue, the transmission path in __dev_queue_xmit() will bypass the qdisc layer. Directly invoking device drivers ndo_start_xmit (via dev_hard_start_xmit). In this mode the device driver is not allowed to ask for packets to be queued (either via returning NETDEV_TX_BUSY or stopping the TXQ). The simplest and most reliable way to identify this no-queue case is by checking if enqueue == NULL. The vrf driver currently open-codes this check (!qdisc->enqueue). While functionally correct, this low-level detail is better encapsulated in a dedicated helper for clarity and long-term maintainability. To make this behavior more explicit and reusable, this patch introduce a new helper: qdisc_txq_has_no_queue(). Helper will also be used by the veth driver in the next patch, which introduces optional qdisc-based backpressure. This is a non-functional change. Reviewed-by: David Ahern Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Jesper Dangaard Brouer Link: https://patch.msgid.link/174559293172.827981.7583862632045264175.stgit@firesoul Signed-off-by: Jakub Kicinski Stable-dep-of: a14602fcae17 ("veth: reduce XDP no_direct return section to fix race") Signed-off-by: Sasha Levin --- drivers/net/vrf.c | 4 +--- include/net/sch_generic.h | 8 ++++++++ 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 89dde220058a2..b62462d8eff26 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -352,15 +352,13 @@ static int vrf_ifindex_lookup_by_table_id(struct net *net, u32 table_id) static bool qdisc_tx_is_default(const struct net_device *dev) { struct netdev_queue *txq; - struct Qdisc *qdisc; if (dev->num_tx_queues > 1) return false; txq = netdev_get_tx_queue(dev, 0); - qdisc = rcu_access_pointer(txq->qdisc); - return !qdisc->enqueue; + return qdisc_txq_has_no_queue(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 a9d7e9ecee6b5..1e002b1dea629 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -803,6 +803,14 @@ static inline bool qdisc_tx_changing(const struct net_device *dev) return false; } +/* "noqueue" qdisc identified by not having any enqueue, see noqueue_init() */ +static inline bool qdisc_txq_has_no_queue(const struct netdev_queue *txq) +{ + struct Qdisc *qdisc = rcu_access_pointer(txq->qdisc); + + return qdisc->enqueue == NULL; +} + /* Is the device using the noop qdisc on all queues? */ static inline bool qdisc_tx_is_noop(const struct net_device *dev) { -- 2.51.0