From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D9837CA6007 for ; Thu, 8 Oct 2026 12:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MZHTc2XGNHdP9T9wX+Y/zZCgi5wtLXlmsEo+S/aR7wI=; b=ESr5UHWm5cLKSCq7ZrlUKqPUYw vX2IObWL6hIu4RVd0bDiuMNRrOJc5hlpkZIROOdWZT3oBsH4vD5RyKzJy8vK6xETStlpcWygVgdm0 63EYlrEOjvMEWByvMSEt5hGgUU4r/zNyMwpvRK+xz8W6fWCM81YNbz1qQIJNiyOILbtEd8dCfW6w2 +OXICYj42MXBk/4V7ylg5+TDhE5jxlbYS5a9FM89Fv6ncXMsG2adfGWKeOEGEY9Xkf8IciBEWQH79 rkg/RV3s3kn0kr7qPvE2NetO8klGFv+dwhWR8xBDzCarAHEUkP9Dd4UDnZBkS8hybGSTxWkCssTWw 1fjQb/tQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xEnb5-00000004OgM-3J45; Thu, 08 Oct 2026 12:51:43 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xEnb2-00000004OfX-30rT for linux-arm-kernel@lists.infradead.org; Thu, 08 Oct 2026 12:51:42 +0000 From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1791463896; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MZHTc2XGNHdP9T9wX+Y/zZCgi5wtLXlmsEo+S/aR7wI=; b=oqlV/79ErOldFxJBOdcaqgayLC1WO3eZpEN29TjkzEPG9yeDcs8gdtjc9MkzQWX1rpGAWk 5vi1xpgk3Vu29SzvFR/YejSai7+xU+PeowDuSFokRn7V/m9fbPhEE8aD+5s7FuhungAkLX HbMeJzHdfeFwKXAwhxM9oFyIg9qr6KkOXcTYSQrNU0lGd9Oti6U/PMz4VlLFd7hZ73XuGI 82EUKS5Vy66VsQFjY+IbiWKRR0dUJir3mAfeslMBlFvb8dnf93cctKMh7opMm7fNgSu+ME kQ9P8AjA8Gnw9mHgh0AlA1WbZXK+0MVp25/90RaD4W2RFUdz+FXaeyBjC8xmjQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1791463896; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MZHTc2XGNHdP9T9wX+Y/zZCgi5wtLXlmsEo+S/aR7wI=; b=66s1G752KnxZk6pqlIIlWCpoYLU30j4kYu9SQMwYjN5bZI5zizQmsN1mZI+ECsY0yN9TCZ GNos/tFHRSHOzTDQ== To: Maciej Fijalkowski Cc: Maxime Chevallier , Andrew Lunn , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Eric Dumazet , Maxime Coquelin , Alexandre Torgue , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Song Yoong Siang , Noor Azura Ahmad Tarmizi , Mohd Faizal Abdul Rahim , Ong Boon Leong , Sebastian Andrzej Siewior , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [PATCH net v2 2/2] net: stmmac: Stop Tx queue when (en|dis)abling XSK pools In-Reply-To: References: <20261005-stmmac_xsk_crashes-v2-0-46c60cba6421@linutronix.de> <20261005-stmmac_xsk_crashes-v2-2-46c60cba6421@linutronix.de> Date: Thu, 08 Oct 2026 14:51:35 +0200 Message-ID: <8733ugqrs8.fsf@jax.kurt.home> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261008_055140_900332_5FA73B82 X-CRM114-Status: GOOD ( 17.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi Maciej, On Thu Oct 08 2026, Maciej Fijalkowski wrote: > On Mon, Oct 05, 2026 at 09:09:33AM +0200, Kurt Kanzenbach wrote: >> When enabling or disabling XSK pools in parallel to Tx traffic, kernel >> crashes occur. For VLAN tagged frames that happens in stmmac_xmit() -> >> dwmac4_set_vlan_tag() and for normal frames in stmmac_xmit() -> >> dwmac4_set_addr(). Both of these functions access the Tx DMA descriptors. >>=20 >> The XDP pool (en|dis)ablement frees and reallocates the Tx DMA resources: >>=20 >> stmmac_disable_tx_queue: >> __free_dma_tx_desc_resources >>=20 >> stmmac_enable_tx_queue: >> __alloc_dma_tx_desc_resources >> __init_dma_tx_desc_rings >>=20 >> NAPI is disabled during that allocation window, but the Tx queue is not >> stopped. Therefore, add the stopping of the Tx queue during the enabling >> and disabling of XSK pools. Update trans_start when stopping the queue >> to avoid spurious watchdog timeouts. >>=20 >> The issue can be easily reproduced by: >>=20 >> 1. Run iperf >> 2. Run application which opens an AF_XDP/ZC socket >>=20 >> Fixes: 132c32ee5bc0 ("net: stmmac: Add TX via XDP zero-copy socket") >> Signed-off-by: Kurt Kanzenbach >> --- >> drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c | 14 ++++++++++++++ >> 1 file changed, 14 insertions(+) >>=20 >> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c b/drivers/= net/ethernet/stmicro/stmmac/stmmac_xdp.c >> index d7e4db7224b0..883bd3fe8089 100644 >> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c >> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c >> @@ -6,6 +6,16 @@ >> #include "stmmac.h" >> #include "stmmac_xdp.h" >>=20=20 >> +static void stmmac_xdp_stop_tx_queue(struct stmmac_priv *priv, u16 queu= e) >> +{ >> + struct netdev_queue *nq =3D netdev_get_tx_queue(priv->dev, queue); >> + >> + __netif_tx_lock_bh(nq); >> + txq_trans_cond_update(nq); >> + netif_tx_stop_queue(nq); >> + __netif_tx_unlock_bh(nq); >> +} >> + >> static int stmmac_xdp_enable_pool(struct stmmac_priv *priv, >> struct xsk_buff_pool *pool, u16 queue) >> { >> @@ -36,6 +46,7 @@ static int stmmac_xdp_enable_pool(struct stmmac_priv *= priv, >> if (need_update) { >> napi_disable(&ch->rx_napi); >> napi_disable(&ch->tx_napi); >> + stmmac_xdp_stop_tx_queue(priv, queue); > > FWIW you can look at what I did at ice driver (ice_qp_dis()) where I used > a bigger hammer here; I think updating trans_start is kinda a workaround. > > https://lore.kernel.org/netdev/20240708221416.625850-1-anthony.l.nguyen@i= ntel.com/ > Actually, trans_start is already updated by netif_tx_stop_queue(). I'd just remove txq_trans_cond_update() for next version. 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