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Miller" CC: Saeed Mahameed , Mark Bloch , "Leon Romanovsky" , Simon Horman , Kees Cook , Patrisious Haddad , Parav Pandit , Gal Pressman , , , , Dragos Tatulea References: <20260423123104.201552-1-tariqt@nvidia.com> <20260423123104.201552-5-tariqt@nvidia.com> Content-Language: en-US From: Shay Drori In-Reply-To: <20260423123104.201552-5-tariqt@nvidia.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: rnnvmail201.nvidia.com (10.129.68.8) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF0000B077:EE_|DS7PR12MB6046:EE_ X-MS-Office365-Filtering-Correlation-Id: 7dcbf6c0-dbcb-460e-7078-08dea3977a4a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|82310400026|36860700016|56012099003|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(376014)(7416014)(1800799024)(82310400026)(36860700016)(56012099003)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: ssW+25ztXBCQxNoC5wzT7fTQ/7H1rzp5priSCa1oS21DLMGXQ+/nxoMzlfPlvPPRHO94iPDEY+mpBMWai4DkMQs9CPQui9SJ2P7SnWRjBHKkt3PnIof+He76upWZjHwOIjxIrPzmajL5JU3kIdGbeJS43T8uIc2WPyjmQaNeatWkS0IuqAsYsSkv8jvWJz7k4TTiHDvvjX9UpWiTMz9I7WoP/tVJLGoVghBMwOHWQEAKIT+uoaKw5jPd/jBwKNZlR4RFeunoiJorNsO0ooW2Z05U4l1nRb6ipJRaDt3gasGKvcewYE3OSwQH/m18Tl1gLZ1tr/6flaled+tQJ/nHNllQm2jZSxRiwc+4Ub4byB3Ka2UGzWoxYkCIMvd/1NymfgieGbUTG67E/beIpL5/IEUPLma4KA9UCPLuT8J2tuodlAwcU+RCkzonZJLzaIqC X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Apr 2026 13:26:51.8315 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7dcbf6c0-dbcb-460e-7078-08dea3977a4a X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF0000B077.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB6046 On 23/04/2026 15:31, Tariq Toukan wrote: > From: Shay Drory > > When utilizing Socket-Direct single netdev functionality the driver > resolves the actual auxiliary device using mlx5_sd_get_adev(). However, > the current implementation returns the primary ETH auxiliary device > without holding the device lock, leading to a potential race condition > where the ETH device could be unbound or removed concurrently during > probe, suspend, resume, or remove operations.[1] > > Fix this by introducing mlx5_sd_put_adev() and updating > mlx5_sd_get_adev() so that secondaries devices would acquire the device > lock of the returned auxiliary device. After the lock is acquired, a > second devcom check is needed[2]. > In addition, update The callers to pair the get operation with the new > put operation, ensuring the lock is held while the auxiliary device is > being operated on and released afterwards. > > The "primary" designation is determined once in sd_register(). It's set > before devcom is marked ready, and it never changes after that. > In Addition, The primary path never locks a secondary: When the primary > device invoke mlx5_sd_get_adev(), it sees dev == primary and returns. > no additional lock is taken. > Therefore lock ordering is always: secondary_lock -> primary_lock. The > reverse never happens, so ABBA deadlock is impossible. > > [1] > for example: > BUG: kernel NULL pointer dereference, address: 0000000000000370 > PGD 0 P4D 0 > Oops: Oops: 0000 [#1] SMP > CPU: 4 UID: 0 PID: 3945 Comm: bash Not tainted 6.19.0-rc3+ #1 NONE > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 > RIP: 0010:mlx5e_dcbnl_dscp_app+0x23/0x100 [mlx5_core] > Call Trace: > > mlx5e_remove+0x82/0x12a [mlx5_core] > device_release_driver_internal+0x194/0x1f0 > bus_remove_device+0xc6/0x140 > device_del+0x159/0x3c0 > ? devl_param_driverinit_value_get+0x29/0x80 > mlx5_rescan_drivers_locked+0x92/0x160 [mlx5_core] > mlx5_unregister_device+0x34/0x50 [mlx5_core] > mlx5_uninit_one+0x43/0xb0 [mlx5_core] > remove_one+0x4e/0xc0 [mlx5_core] > pci_device_remove+0x39/0xa0 > device_release_driver_internal+0x194/0x1f0 > unbind_store+0x99/0xa0 > kernfs_fop_write_iter+0x12e/0x1e0 > vfs_write+0x215/0x3d0 > ksys_write+0x5f/0xd0 > do_syscall_64+0x55/0xe90 > entry_SYSCALL_64_after_hwframe+0x4b/0x53 > > [2] > CPU0 (primary) CPU1 (secondary) > ========================================================================== > mlx5e_remove() (device_lock held) > mlx5e_remove() (2nd device_lock held) > mlx5_sd_get_adev() > mlx5_devcom_comp_is_ready() => true > device_lock(primary) > mlx5_sd_get_adev() ==> ret adev > _mlx5e_remove() > mlx5_sd_cleanup() > // mlx5e_remove finished > // releasing device_lock > //need another check here... > mlx5_devcom_comp_is_ready() => false > > Fixes: 381978d28317 ("net/mlx5e: Create single netdev per SD group") > Signed-off-by: Shay Drory > Signed-off-by: Tariq Toukan > --- > .../net/ethernet/mellanox/mlx5/core/en_main.c | 10 ++++++++++ > .../net/ethernet/mellanox/mlx5/core/lib/sd.c | 17 +++++++++++++++++ > .../net/ethernet/mellanox/mlx5/core/lib/sd.h | 2 ++ > 3 files changed, 29 insertions(+) I went over all Sashiko comments on this patch and they are false positive > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > index 9c340ad2fe09..c4cb5369f0a0 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > @@ -6778,11 +6778,14 @@ static int mlx5e_resume(struct auxiliary_device *adev) > err = _mlx5e_resume(actual_adev); > if (err) > goto sd_cleanup; > + mlx5_sd_put_adev(actual_adev, adev); > } > return 0; > > sd_cleanup: > mlx5_sd_cleanup(mdev); > + if (actual_adev) > + mlx5_sd_put_adev(actual_adev, adev); > return err; > } > > @@ -6822,6 +6825,8 @@ static int mlx5e_suspend(struct auxiliary_device *adev, pm_message_t state) > err = _mlx5e_suspend(actual_adev, false); > > mlx5_sd_cleanup(mdev); > + if (actual_adev) > + mlx5_sd_put_adev(actual_adev, adev); > return err; > } > > @@ -6923,11 +6928,14 @@ static int mlx5e_probe(struct auxiliary_device *adev, > err = _mlx5e_probe(actual_adev); > if (err) > goto sd_cleanup; > + mlx5_sd_put_adev(actual_adev, adev); > } > return 0; > > sd_cleanup: > mlx5_sd_cleanup(mdev); > + if (actual_adev) > + mlx5_sd_put_adev(actual_adev, adev); > return err; > } > > @@ -6980,6 +6988,8 @@ static void mlx5e_remove(struct auxiliary_device *adev) > _mlx5e_remove(actual_adev); > > mlx5_sd_cleanup(mdev); > + if (actual_adev) > + mlx5_sd_put_adev(actual_adev, adev); > } > > static const struct auxiliary_device_id mlx5e_id_table[] = { > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c > index 897b0d81b27d..f7b226823ab4 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c > @@ -538,6 +538,10 @@ void mlx5_sd_cleanup(struct mlx5_core_dev *dev) > sd_cleanup(dev); > } > > +/* Cannot take devcom lock as a gate for device lock. ABBA deadlock: > + * primary: actual_adev_lock -> SD devcom comp lock > + * secondary: SD devcom comp lock -> actual_adev_lock > + */ > struct auxiliary_device *mlx5_sd_get_adev(struct mlx5_core_dev *dev, > struct auxiliary_device *adev, > int idx) > @@ -555,5 +559,18 @@ struct auxiliary_device *mlx5_sd_get_adev(struct mlx5_core_dev *dev, > if (dev == primary) > return adev; > > + device_lock(&primary->priv.adev[idx]->adev.dev); > + /* In case primary finish removing its adev */ > + if (!mlx5_devcom_comp_is_ready(sd->devcom)) { > + device_unlock(&primary->priv.adev[idx]->adev.dev); > + return NULL; > + } > return &primary->priv.adev[idx]->adev; > } > + > +void mlx5_sd_put_adev(struct auxiliary_device *actual_adev, > + struct auxiliary_device *adev) > +{ > + if (actual_adev != adev) > + device_unlock(&actual_adev->dev); > +} > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h > index 137efaf9aabc..9bfd5b9756b5 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h > +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h > @@ -15,6 +15,8 @@ struct mlx5_core_dev *mlx5_sd_ch_ix_get_dev(struct mlx5_core_dev *primary, int c > struct auxiliary_device *mlx5_sd_get_adev(struct mlx5_core_dev *dev, > struct auxiliary_device *adev, > int idx); > +void mlx5_sd_put_adev(struct auxiliary_device *actual_adev, > + struct auxiliary_device *adev); > > int mlx5_sd_init(struct mlx5_core_dev *dev); > void mlx5_sd_cleanup(struct mlx5_core_dev *dev);