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 024744C91; Fri, 16 May 2025 00:52:53 +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=1747356774; cv=none; b=Hzz+DYiti/A09lvNJAIIzAN8miaBIyzr6T7hcUqp5M0jJYQIJWK5cEA/A85jdn5NLkeNwDx3nNUGj/FX1IONfEf4NsWGBJsqPoyecK1OD5P3dATcFLDQiwgV31JEBWex3lSod7yXYywWPTzVx/0MeHqgzl4x3cEC1eI3kZwSl0Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747356774; c=relaxed/simple; bh=W4XvKUUpI1NuoyrHwx51qsaD68pHRMjadUnfOiZwxE8=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=T+ZE/kMZ/7ebxBblNKST2mRz6CM2l5VIpOiYwzq3/ArwRXcgaw43Cbv6NmbP10HRqkD/noETA2ZYaBAFbedPDUmA4IHLihMFpV8L5ztIUzyaSZrNVL6qYl5OzvmWRQv5mtJ8Ys7GoZxEaPpOWk0pAAD5DkJXauOo2+Tv387D6I0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CpNCw2K5; 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="CpNCw2K5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6926EC4CEE7; Fri, 16 May 2025 00:52:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747356773; bh=W4XvKUUpI1NuoyrHwx51qsaD68pHRMjadUnfOiZwxE8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=CpNCw2K54cXl1rkR48zAeUVMW7/fudU4soX9CFb4lUusKu2f9ZpdLF+ezxUlVUShR kApJXAwkj5Ft9u+K6tv2d3huqCJp0gQ+9EGddd4/TAahTkl7P+RHznu0yaMzmT6/4Q qJEsGB/IZg0SMUKdofMuVQNNOH1E6Pa4QxOm4p9UQq5+/kr6AF2uehMX5rcHQ3dwYn Xkj8ub/YvVOJkippnp0cUQk2GUY+SJn0CXjUwZ06cdnJJQzw5kxUhjzLoz22MAKMvx rNQecW8QT0sAWW7KseycQY22QXS8mRidLknoCjaaBsvY69hst3KbAFqF2iPvv4zo9g GEBrSj9ketR7g== Date: Thu, 15 May 2025 17:52:51 -0700 From: Jakub Kicinski To: Jinjian Song Cc: chandrashekar.devegowda@intel.com, chiranjeevi.rapolu@linux.intel.com, haijun.liu@mediatek.com, m.chetan.kumar@linux.intel.com, ricardo.martinez@linux.intel.com, loic.poulain@linaro.org, ryazanov.s.a@gmail.com, johannes@sipsolutions.net, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, angelogioacchino.delregno@collabora.com, linux-arm-kernel@lists.infradead.org, matthias.bgg@gmail.com, corbet@lwn.net, linux-mediatek@lists.infradead.org, helgaas@kernel.org, danielwinkler@google.com, andrew+netdev@lunn.ch, horms@kernel.org Subject: Re: [net v1] net: wwan: t7xx: Fix napi rx poll issue Message-ID: <20250515175251.58b5123f@kernel.org> In-Reply-To: <20250515031743.246178-1-jinjian.song@fibocom.com> References: <20250515031743.246178-1-jinjian.song@fibocom.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 15 May 2025 11:17:42 +0800 Jinjian Song wrote: > diff --git a/drivers/net/wwan/t7xx/t7xx_netdev.c b/drivers/net/wwan/t7xx/t7xx_netdev.c > index 91fa082e9cab..2116ff81728b 100644 > --- a/drivers/net/wwan/t7xx/t7xx_netdev.c > +++ b/drivers/net/wwan/t7xx/t7xx_netdev.c > @@ -324,6 +324,7 @@ static void t7xx_ccmni_wwan_dellink(void *ctxt, struct net_device *dev, struct l > if (WARN_ON(ctlb->ccmni_inst[if_id] != ccmni)) > return; > > + ctlb->ccmni_inst[if_id] = NULL; > unregister_netdevice(dev); I don't see any synchronization between this write and NAPI processing. Is this safe? NAPI can be at any point of processing as we set the ptr to NULL -- pw-bot: cr From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from TYPPR03CU001.outbound.protection.outlook.com (mail-japaneastazon11022113.outbound.protection.outlook.com [52.101.126.113]) (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 0B9402C9A; Fri, 16 May 2025 07:30:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.126.113 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747380662; cv=fail; b=u9tYaIfNG2AETzRpuacgGLjImgDqzNhNm9C+Xmu+ivXkelaoE/T6zFvwfL3ZiTKYIDy82FQkzfHYYng8UqVT/9cLGGprjNjZqtnUlfzJo06Qv40n6c6toGbtm9OHLdQTA735Y9vzzztJXhtXU3+RVlZx7elJ5CB07GP2aztNI3Q= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747380662; c=relaxed/simple; bh=Ptc8EzBRSluU0Pjj49UvdaaQ2cVaMLRwJpn7NuXWqqY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: Content-Type:MIME-Version; b=XpWcYHWRdYKgVXskpHRMyn2jSycUk/BhlIoreOQNLNLI1DrDkN9F6iXCOuxhV2pI3m7XTFROKGI8PxiufRkGL7UUunpD/RuLl8ma78lfH2oZ5kFiA9GisGo07oIjieY4n/HVmu4nEU1SawxNMts4RP7doPWpjgcOawC9y5N4fkk= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=fibocom.com; spf=pass smtp.mailfrom=fibocom.com; dkim=pass (1024-bit key) header.d=fibocomcorp.onmicrosoft.com header.i=@fibocomcorp.onmicrosoft.com header.b=v4Y+gQUv; arc=fail smtp.client-ip=52.101.126.113 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=fibocom.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fibocom.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=fibocomcorp.onmicrosoft.com header.i=@fibocomcorp.onmicrosoft.com header.b="v4Y+gQUv" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=spkrQPyBMRqS8Vl+5V9RWQxNOmHt8jumLWW4oGPagvmRCm1jTEZAkAUS4XSqGSu2OsN8y+gPEsAdj/YIWcoW0P99DIIjOJdXvjcFEroYhr3/fvY9z36jJ7Zh51vInoffTRTLYQN7CpHcLZ1I2oqqxnE0Sb6FdrDhjRgkHB5ftrkjh0gzYssJ7f+73va7Pa5Ag2EKyjYY/N1cAV1+BT/NGLCmtol364g74+n/HM/X6O8R99j1cS7loXaTj3gI7Enej/isCbwVMWrn+VoL6lYkY8T+HppsKHKgQ8FJdfp4zfV9kkKtclbGGo37h3L19ZYipb2JHmnrPWXBV2TAuPUxMw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=SH04AcPUq/K8MnElCpiV9Bq9ATRB6A3kg08SBjFjQ04=; b=tp0+TbVxwXzctVvqiFcvBoNz256p6ZjSE9Rnug4TGoSwHjr03hIjNEoHhYeQPXog2CeN5ZlfLIiHE87spI4FU6rOYO+/30hxm6z4Mr58Vplb8U33ao70X88aBYscwN6+lV7uQJHbidW1pzh8uUAZVeTDGBce/GO2KjmW/R2pa9Tjf/rRhRKY1EP5a7fdE7LVQj4AdzdrgQgESb945MbH0sxVsFw/y6JyS08Ire/Tsp2FLqELJ6KC0RXNjc4O2dO2hDnlyqqr21ZL4azqOyk0m0PNcrtHMPFrBEAMNbIJM1YJggK6L1d+CeOT04N0/78rAFoyaBc3O2FF+O3SyMmZNQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fibocom.com; dmarc=pass action=none header.from=fibocom.com; dkim=pass header.d=fibocom.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fibocomcorp.onmicrosoft.com; s=selector1-fibocomcorp-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=SH04AcPUq/K8MnElCpiV9Bq9ATRB6A3kg08SBjFjQ04=; b=v4Y+gQUvv4oQMKvQGusaTBlOCIyOVRKnyQl+BJP3m2ev1jJ5pO9GcL+XCyU9l42MF1Mn5dsV4rv3xXSJFG7fN8JRTA4inQBxoWROjBN1BlwZpNCRmcw8R8tkxNVOdckUkarvPh+xuxKV4NFn15teM7HN/a0ylrtCrWeYXTD0cMI= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=fibocom.com; Received: from TY0PR02MB5766.apcprd02.prod.outlook.com (2603:1096:400:1b5::6) by SEZPR02MB6177.apcprd02.prod.outlook.com (2603:1096:101:a8::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8722.32; Fri, 16 May 2025 07:30:52 +0000 Received: from TY0PR02MB5766.apcprd02.prod.outlook.com ([fe80::f53d:47b:3b04:9a8b]) by TY0PR02MB5766.apcprd02.prod.outlook.com ([fe80::f53d:47b:3b04:9a8b%4]) with mapi id 15.20.8722.027; Fri, 16 May 2025 07:30:52 +0000 From: Jinjian Song To: kuba@kernel.org Cc: andrew+netdev@lunn.ch, angelogioacchino.delregno@collabora.com, chandrashekar.devegowda@intel.com, chiranjeevi.rapolu@linux.intel.com, corbet@lwn.net, danielwinkler@google.com, davem@davemloft.net, edumazet@google.com, haijun.liu@mediatek.com, helgaas@kernel.org, horms@kernel.org, jinjian.song@fibocom.com, johannes@sipsolutions.net, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, loic.poulain@linaro.org, m.chetan.kumar@linux.intel.com, matthias.bgg@gmail.com, netdev@vger.kernel.org, pabeni@redhat.com, ricardo.martinez@linux.intel.com, ryazanov.s.a@gmail.com Subject: Re: [net v1] net: wwan: t7xx: Fix napi rx poll issue Date: Fri, 16 May 2025 15:30:38 +0800 Message-ID: <20250515175251.58b5123f@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250515031743.246178-1-jinjian.song@fibocom.com> References: <20250515031743.246178-1-jinjian.song@fibocom.com> Precedence: bulk Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SI2PR02CA0023.apcprd02.prod.outlook.com (2603:1096:4:195::11) To TY0PR02MB5766.apcprd02.prod.outlook.com (2603:1096:400:1b5::6) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: TY0PR02MB5766:EE_|SEZPR02MB6177:EE_ X-MS-Office365-Filtering-Correlation-Id: 1be273a2-c0f3-4007-3bc3-08dd944b95fc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|4022899009|366016|376014|7416014|52116014|1800799024|38350700014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Ivhm4e4qZX33036nO2TfwBO3Fom6ILt3m8yf+9ZLB7eVK3ydQf6BuE3gkFv8?= =?us-ascii?Q?w5nwZvx3Iw4+xfJjHO2Z5Kb/Zlf8S3dQTvErxi/mqwlrXSPvNZr/sekaO9dY?= =?us-ascii?Q?twTcGY/wGn7X9wVV2a9NCmLysxht4W34poiTx3oO/ShR2ZJWtqg9ENdVCrZo?= =?us-ascii?Q?O3ZWE+40r34Y7NK4HokZDLvhy8Sp22qJWPbHTuVw6mBanQ3PKZeGjSkqA/OQ?= =?us-ascii?Q?hFqWCcog2T7n+Zog05YnTXjmLvxRGCVNgoWSp7Pe/ENGZJpMNiBqHxSJbe7B?= =?us-ascii?Q?tr1rp+imVrJseuypO9rlNC3/wuf70E9QZ7Dfa+ErBj0+k1o3aDbHoJZA97R2?= =?us-ascii?Q?9m6HpRQcs3nBgeYLxicCoTZpGPUHVlb7CRHUT5GPF4HQg52pk7W2QjeLSlB3?= =?us-ascii?Q?u/jxm1pEPs74gJMiQAPwIXAryIDbzWKcrxqOuWnqXEGPxD35b6TJalxhdW7L?= =?us-ascii?Q?Yxzwt+OSI9NjhTiXVyK6GWkpUBA+zC/6tR9nIUnJkN1mkFPv/ExHt/egOJJZ?= =?us-ascii?Q?peDUqyHImw5btUCkeC0MZPlMm9c+SLvHPAPzAsyRJf0FMIrBF58dr+wxdoWC?= =?us-ascii?Q?XuHZPeCiemWbQRR3LuNkSQ7UhpHM1mqNwP/v5iap4ARqL1hmefxPmtVeSb+l?= =?us-ascii?Q?BYdJvHuEQDEm8XDDKv9vQKIz8X7nkIeb1mxSQyomROguLac3qG+pcpQCQtAA?= =?us-ascii?Q?pinGq2SpJJHpMJnGgBEb5PsQqKaFRG5gMjtiKbCQPDPo7xlTNrALRfVNtbMq?= =?us-ascii?Q?hhWgOA/uiLdhIqx8PgIEZCoOER1Dwwt2zu/Aunbql/V+gwe3CfPYBHLI1uSP?= =?us-ascii?Q?/R/dMrtOmMfebJ99PRj6lw/dy36ceNXKHF2ptqDzczWIKjIUK8ZZT973T2FL?= =?us-ascii?Q?lApJWwI1FNsmrPcP9kUHhqlJihsG6DI2dIQNZCEANySQ1k+WbUXpxTB+R9wN?= =?us-ascii?Q?ELXvKvYiGpcjlEvD65ejWLLwrqNW9kz8Vb3cwx2IHxodMLWOHEJK75r1EVGL?= =?us-ascii?Q?ugd4JiwPzkTiFZwVZEip99R8RBybRcMo9wSQWoyq4yrBayKOcUddfTm2ABZB?= =?us-ascii?Q?ATLkUFaxLRNxkHeSC6WY3wstuY7gTwyfBbSgVIvy898JG3Yy7mdP1ez8ejQH?= =?us-ascii?Q?6f5Ln1R1YFVc73UM4EHYz4UgvudAhW31N6CG4AfVaazUGcbWuIMQnq84PMFJ?= =?us-ascii?Q?44Mh1sGePqK+OD0qc4wQfm7gz3NWL7FpORw2UudsjojOYZOByUeyw7VJqf97?= =?us-ascii?Q?YuoyHyWd+04/3kYVYMCKV4ubyMdrLBDa/ZOinK5I7ppUpG6EJD3D5AZblDhE?= =?us-ascii?Q?QLB0pd9rE1fkMPU9VoUKkcsW922UhU1F6j37YJ+sdKi5dbmFtaw+G/xyakAf?= =?us-ascii?Q?LpiWYV9m2E1X+iZSPXj0vAww9C9sdjawOQ4bR6GyyyYrm72LugjoPduA1otS?= =?us-ascii?Q?/6H7e7f3eIN+y4p3J0dVHrLwBoFEUryBhiq7BsF87Hnr83Sl+mYtlQ=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:TY0PR02MB5766.apcprd02.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(4022899009)(366016)(376014)(7416014)(52116014)(1800799024)(38350700014);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?BTpwpAyVvyUkXGz9YcLxu1se7yMmrRZ/uqrdnQKn80e08x5UoXrnFbRXPxP5?= =?us-ascii?Q?NF2qkX18tZwe62lQeg6XS9sdLw6Z8x8ZyCkHmbZM9q5SVgSasTDgkvUX1X12?= =?us-ascii?Q?9iMkanPZdRkHvhO5SzyYDRMKa1qDHvFgFpXxduCzKouElX+x7crMlnDbLd6b?= =?us-ascii?Q?3OaHcdy//4SLmyx+VX+CMBNW5T3edN82xZvOOeE/jl18peWAMb1pbQgebczm?= =?us-ascii?Q?t/A8aRYfxL8mo0B8yOyjeuISisLQkbey08Lt/L0Yt4KL9jAgodcDn6x0Yhp3?= =?us-ascii?Q?sn21/hh66EaYF+9f/ReBoyCX6zJMkZCrdTxJ2ovOkvHhVeBDxibw7V1j/QtB?= =?us-ascii?Q?tskQy1/fCNkQwaLDG9WNuL38lcwrG8hCL2V89u77J0RBdAfHlVpC+QzDcMpi?= =?us-ascii?Q?gUtwKU9i07aRVgreRo3mlZlVk4NeX0kV8b77oOG9SChrUVHmGOMPcl7I8Mty?= =?us-ascii?Q?m2JXe9cELhT4Cvq3+vL/jMTJjr3afqOqF7srLcibBV918o/5rvRFnaUxqc/v?= =?us-ascii?Q?sc9/zXItyJmbtC+cds96rDNAbYHi0iqy3dr0hq5r5mqQKJphPsXf7kju1PmF?= =?us-ascii?Q?PDSCq245Y/CvznCnzEWaOBm3EiQK0uE/cnlD7Qud+I2ezbsY1TqIZhsLQUCf?= =?us-ascii?Q?r6bRLx4NzDuqQGiZatpnVgFKL5nQRgDQMNMntRHiYxMCZcaqhT8I0tZQRf6a?= =?us-ascii?Q?po2+/wwnq+P3Efb2cA0IYs6Q6vPP488XIl6GaJ4rfX/uO3PwthQHrfktdPsm?= =?us-ascii?Q?MGBT3/NgerjqA+K9IfIaJzzrlvXwlnUkpjzdEPrp79GwAmPPAlMpFdzb/fjk?= =?us-ascii?Q?7MAVjt32aVebryeSUsVd+oDlF8XsKMx3wFo+o1izI5H2wAYBpJ7tmOh18vPV?= =?us-ascii?Q?wSL41iGxpODGUz1NiJb88yDqh904b4mZQZpSGRFHVj9E8u6oPIV663A62vRr?= =?us-ascii?Q?cMo7pnkDdHBvpfTT0Gn7ee4ecb9CtYSIa+g2Kf0J6pZbbN/qiqkltkLkrEqD?= =?us-ascii?Q?VWOlRmE4xgrknX2fb91qSy5/7KBkNJ4iYsSgBGGzRxgdY8YKORMnRB/HKPje?= =?us-ascii?Q?HVDw7GvgnLvxWfSXD+deUxbGHht7/hEGRXEmY+vPtBk/FzTBMUDq1xpAOa2H?= =?us-ascii?Q?gMzb1kI1NMgXFSeLntX1jAEmGVgi3FhPu0fHD+TOwZiHVVRc0JW1DZpcTxnF?= =?us-ascii?Q?ze78IVHIRJF2nJgkkrpJ3uH2g2kdHSPvDnjpP9LbaphTKNJRTZZyVQ8BYEZG?= =?us-ascii?Q?WBb+rVhF0JAhFgYgHR2qjax4tRAfZYfMCxdErCzjKxdImYZULyic5a6kYmxd?= =?us-ascii?Q?0bvwvzIIDnPxxP1ya70/ewsGSunmx7D/XGTVaj5k5Q6zenB8uh0tkGuN6McD?= =?us-ascii?Q?3jPnuppe/g5MHu20CEMt0VCNtO1etxg1ueqPRzTFAW09RtXxm1kBsQ1yhXnD?= =?us-ascii?Q?cT5aqZQknqa/ol4oOm0/0DYCYXiRBoNgtrNBRarpPwlWjtG3fL85RIs3cVNq?= =?us-ascii?Q?XWpmNjbaEh1PK2d/NtcIJwVEadP5AsIrXFI4FdJWT/UFBdI7LCROHej198KE?= =?us-ascii?Q?ZJVMQrEhOm0aSLMLiLwDkg1+DbNZiwEZ0RXU/2Npj0n/oFbMNiZGTjdAdYKb?= =?us-ascii?Q?fA=3D=3D?= X-OriginatorOrg: fibocom.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1be273a2-c0f3-4007-3bc3-08dd944b95fc X-MS-Exchange-CrossTenant-AuthSource: TY0PR02MB5766.apcprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 May 2025 07:30:52.0141 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 889bfe61-8c21-436b-bc07-3908050c8236 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: hFA5RvA1kFhVEztvAGpJxJDGhR3vogXaB4N1BpYNxE2FJ+5qhGC7xS18qjmHlAlOxBLuNDLTZTAp2tqc9HjVSj8ZVUfV7ZpZNQNru3Ez0Sg= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SEZPR02MB6177 Message-ID: <20250516073038.4aFr2lnLRV7tNDOwELbt_bBreBl3juz5DzwU4P8OCgw@z> >On Thu, 15 May 2025 11:17:42 +0800 Jinjian Song wrote: >> diff --git a/drivers/net/wwan/t7xx/t7xx_netdev.c b/drivers/net/wwan/t7xx/t7xx_netdev.c >> index 91fa082e9cab..2116ff81728b 100644 >> --- a/drivers/net/wwan/t7xx/t7xx_netdev.c >> +++ b/drivers/net/wwan/t7xx/t7xx_netdev.c >> @@ -324,6 +324,7 @@ static void t7xx_ccmni_wwan_dellink(void *ctxt, struct net_device *dev, struct l >> if (WARN_ON(ctlb->ccmni_inst[if_id] != ccmni)) >> return; >> >> + ctlb->ccmni_inst[if_id] = NULL; >> unregister_netdevice(dev); > >I don't see any synchronization between this write and NAPI processing. >Is this safe? NAPI can be at any point of processing as we set the ptr >to NULL This panic occured in the scenario where there are frequent disconnect and connect WWAN cellular on UI. I debug the panic with gdb and found it as caused by an invalid net_device during this process: 1.-> t7xx_dpmaif_napi_rx_poll 2.-> t7xx_ccmni_recv_skb 3.-> napi_gro_receive 4.-> dev_gro_receive 5.-> netif_elide_gro One way, the net_device using in step 5 is valid, so "dev->features .." panic, this net_device pass from t7xx_ccmni_recv_skb: void t7xx_ccmni_recv_skb(...) { [...] ccmni = ccmni_ctlb->ccmni_inst[netif_id]; if (!ccmni) { dev_kfree_skb(skb); return; } net_dev = ccmni->dev; skb->dev = net_dev; [...] napi_gro_receive(napi, skb); [...] } Another way, WWAN disconnect -> wwan_ops.dellink -> t7xx_ccmni_wwan_dellink -> unregister_netdevice(dev). netdevice has been invalid, so t7xx_dpmaif_napi_rx_poll can't use it any more. I mark ccmni_inst[if_id] = NULL with netdevice invalid at the same time. It seems that a judgment is made every time ccmni_inst[x] is used in the driver, and the synchronization on the 2 way might have been done when NAPI triggers polling by napi_schedule and when WWAN trigger dellink. So this should be safe. Jinjian, Best Regards.