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Sat, 28 Jun 2025 09:52:54 +0000 (GMT) Received: from pps.filterd (iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 55S9LeYF014207; Sat, 28 Jun 2025 09:52:53 GMT Received: from pps.reinject (localhost [127.0.0.1]) by iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 47j6u6r8f8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 28 Jun 2025 09:52:53 +0000 Received: from iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 55S9qqR2009214; Sat, 28 Jun 2025 09:52:52 GMT Received: from ca-dev110.us.oracle.com (ca-dev110.us.oracle.com [10.129.136.45]) by iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTP id 47j6u6r8er-1; Sat, 28 Jun 2025 09:52:52 +0000 From: Alok Tiwari To: sgoutham@marvell.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, netdev@vger.kernel.org Cc: alok.a.tiwari@oracle.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] net: thunderx: avoid direct MTU assignment after WRITE_ONCE() Date: Sat, 28 Jun 2025 02:52:19 -0700 Message-ID: <20250628095221.461991-1-alok.a.tiwari@oracle.com> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.7,FMLib:17.12.80.40 definitions=2025-06-27_05,2025-06-27_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 spamscore=0 suspectscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2505160000 definitions=main-2506280080 X-Proofpoint-GUID: 28NGkk0EG0roxnsCG4rY-kj-ROsDwQTD X-Proofpoint-ORIG-GUID: 28NGkk0EG0roxnsCG4rY-kj-ROsDwQTD X-Authority-Analysis: v=2.4 cv=b82y4sGx c=1 sm=1 tr=0 ts=685fbb76 b=1 cx=c_pps a=e1sVV491RgrpLwSTMOnk8w==:117 a=e1sVV491RgrpLwSTMOnk8w==:17 a=6IFa9wvqVegA:10 a=yPCof4ZbAAAA:8 a=6GJOchzy3z8SWhoumhsA:9 cc=ntf awl=host:14723 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjI4MDA4MSBTYWx0ZWRfX7T9s0A92THvT DX3/F38hBL3wrkdQj1tm0eOzavSjF4r5NyyJKLZa80w+ITNTA159pJEtgZVOsuT/mBgyXuy5u92 h/Rk+1Z091eBZ8b+SbFdPkleE478Mrs4CxDXLTLxWRhrsFkOr+ceIUaQdlLZPao/UVaSZWwjQd1 2qN9DFLlHJ5L9XoCHUo5xZs2hTuub29ak1kQoUdFAxu4F+R/LUIxtR2S4bNgZNSGH8OHtRJHKKZ f/+QmcEo9E7CrV+ueeQaalmwJa0yUcIDFJH2PU5r4EQ2xnsMFYW1JY+NeUCyilA8NS/umCi+CfT oHTqMUesPWoEFnNt5ZQ6rTLBrXr65yJ4ACkYKw9KDooEkHHiNYDvxPA+ASgmo+gkjDDjVHH0iFf /rwyrLZNb1wYeCNAf9b8j9OG4BiayVy6YI/3vZpJMPmNF1lldcNc9r1kbPz3kBRcM5Num4GT Content-Type: text/plain; charset="utf-8" The current logic in nicvf_change_mtu() writes the new MTU to netdev->mtu using WRITE_ONCE() before verifying if the hardware update succeeds. However on hardware update failure, it attempts to revert to the original MTU using a direct assignment (netdev->mtu =3D orig_mtu) which violates the intended of WRITE_ONCE protection introduced in commit 1eb2cded45b3 ("net: annotate writes on dev->mtu from ndo_change_mtu()") Additionally, WRITE_ONCE(netdev->mtu, new_mtu) is unnecessarily performed even when the device is not running. Fix this by: Only writing netdev->mtu after successfully updating the hardware. Skipping hardware update when the device is down, and setting MTU directly. This ensures that all writes to netdev->mtu are consistent with WRITE_ONCE expectations and avoids unintended state corruption on failure paths. Signed-off-by: Alok Tiwari --- Note: This change is not tested due to hardware availability. --- drivers/net/ethernet/cavium/thunder/nicvf_main.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net= /ethernet/cavium/thunder/nicvf_main.c index aebb9fef3f6eb..ba26ba31a28bf 100644 --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c @@ -1589,16 +1589,18 @@ static int nicvf_change_mtu(struct net_device *netd= ev, int new_mtu) return -EINVAL; } =20 - WRITE_ONCE(netdev->mtu, new_mtu); =20 - if (!netif_running(netdev)) + if (!netif_running(netdev)) { + WRITE_ONCE(netdev->mtu, new_mtu); return 0; + } =20 if (nicvf_update_hw_max_frs(nic, new_mtu)) { - netdev->mtu =3D orig_mtu; return -EINVAL; } =20 + WRITE_ONCE(netdev->mtu, new_mtu); + return 0; } =20 --=20 2.46.0