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Wed, 2 Sep 2026 09:40:21 -0700 From: Tariq Toukan To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , Paolo Abeni CC: Akiva Goldberger , Edward Srouji , Gal Pressman , Kees Cook , Leon Romanovsky , , , Maher Sanalla , Mark Bloch , Or Har-Toov , Parav Pandit , Patrisious Haddad , Saeed Mahameed , Shay Drori , Simon Horman , Tariq Toukan Subject: [PATCH net 1/4] net/mlx5: SD, serialize SD LAG init/cleanup against LAG mode changes Date: Wed, 2 Sep 2026 19:37:13 +0300 Message-ID: <20260902163716.3656279-2-tariqt@nvidia.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20260902163716.3656279-1-tariqt@nvidia.com> References: <20260902163716.3656279-1-tariqt@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF0000C381:EE_|DM4PR12MB9069:EE_ X-MS-Office365-Filtering-Correlation-Id: 74d37b64-40ef-40b4-3d8f-08df0910f2cf X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|23010399003|82310400026|7416014|376014|1800799024|6133799003|56012099006|10067099003|11063799006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.232;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge1.nvidia.com;CAT:NONE;SFS:(13230040)(36860700016)(23010399003)(82310400026)(7416014)(376014)(1800799024)(6133799003)(56012099006)(10067099003)(11063799006)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: jAM0DVhjWcFZgipwT6Ez4j6phwlys7Vgm+O6NXv3mAkGzZq1Zpm+86dlgsExu6/yFjmix1yrZAXyxe5d66E9tPJoh/5n6wf7oYnUblG9LjZGw3U3q+BReP5LKC3NYWUEfB5riy5LmgbUdr4kPPsbFXbjsISfeGhuDqX7RAfD5EkGIdHAPxCj50xFrqBBNDZ9LdQSdn3St2JSusCkHKyKsPvmsM1Mk6CzkMtqoUo4L7DhgwTA+vLauh0T8m/OtTouCIJtGzSHDZI3oF23UncN6Yzxus1/tR518Sm9HpoXE46zjzPwbsdc0EcsjdxiJfoWVaIaUjC0A+3idP5vifWRKsvNB6NHXiP8DByErhxNjkPHKbGNCz1Mk4KXcizV1oA/mSlK4FsVnaBRfT2mawmrRAETLXZTdd1hsVxfRYUZsAe1RP9hvIEOdr4QoJKYqkXe X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Sep 2026 16:40:50.6354 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 74d37b64-40ef-40b4-3d8f-08df0910f2cf X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF0000C381.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB9069 From: Shay Drory A secondary SD is spliced into the primary's shared LAG device (ldev) by sd_lag_init() and removed by sd_lag_cleanup(). The LAG mode-change paths drop ldev->lock mid-operation while iterating ldev->pfs, and rely on ldev->mode_changes_in_progress to keep the member set stable across that window. sd_lag_cleanup() did not honor ldev->mode_changes_in_progress. Which means a concurrent SD teardown could xa_erase() and kfree() a pf out of ldev->pfs during a mode change's dropped-lock window, leading to a NULL/use-after-free dereference of the secondary pf. Make sd_lag_init() and sd_lag_cleanup() wait until mode_changes_in_progress drops to zero before touching ldev, mirroring mlx5_lag_remove_mdev(). In addition, fold the SD shared-FDB teardown in mlx5_lag_disable_change() into the main locked section. Otherwise the two acquire sd_devcom and mode_changes_in_progress in opposite orders - sd_lag_init/cleanup takes sd_devcom then waits on mode_changes_in_progress, while disable_change increments mode_changes_in_progress then takes sd_devcom - an ABBA deadlock. The same ABBA deadlock is present in mlx5_eswitch_disable(), which takes sd_devcom between mlx5_lag_disable_change() and mlx5_lag_enable_change(). Move that call after mlx5_lag_enable_change(), matching the ordering already used by mlx5_devlink_eswitch_mode_set(). Fixes: 3c103110835d ("net/mlx5: SD, introduce Socket Direct LAG") Signed-off-by: Shay Drory Reviewed-by: Akiva Goldberger Signed-off-by: Tariq Toukan --- .../net/ethernet/mellanox/mlx5/core/eswitch.c | 2 +- .../net/ethernet/mellanox/mlx5/core/lag/lag.c | 30 +++++++++---------- .../net/ethernet/mellanox/mlx5/core/lib/sd.c | 13 ++++++++ 3 files changed, 28 insertions(+), 17 deletions(-) Internal sashiko comment: diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c > index ee2fdefa1945..2b2b7f3916f7 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c > @@ -342,7 +342,14 @@ static void sd_lag_init(struct mlx5_core_dev *dev) > return; > } > > +recheck: > mutex_lock(&ldev->lock); > + if (ldev->mode_changes_in_progress) { > + mutex_unlock(&ldev->lock); > + msleep(100); > + goto recheck; > + } > + Does this open-coded retry loop reimplement a wait mechanism without immediate wakeups or fairness? It looks like we are polling the mode_changes_in_progress flag using a hard coded msleep(100). Could this unnecessarily delay the initialization path if the condition clears much sooner than 100ms? Would it be better to use a proper synchronization primitive like a waitqueue here instead of an ad-hoc flag loop? [SD] This is the same check as in mlx5_lag_remove_mdev(). I agree we need to change it, but this is net-next material diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c index b6e2c153b4f7..50e158b6a684 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c @@ -2062,8 +2062,8 @@ void mlx5_eswitch_disable(struct mlx5_eswitch *esw) mlx5_esw_reps_unblock(esw); esw->mode = MLX5_ESWITCH_LEGACY; - mlx5_sd_eswitch_mode_set(esw->dev, MLX5_ESWITCH_LEGACY); mlx5_lag_enable_change(esw->dev); + mlx5_sd_eswitch_mode_set(esw->dev, MLX5_ESWITCH_LEGACY); } static int mlx5_esw_sf_max_pf_functions(struct mlx5_core_dev *dev, diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c index 2285c889c215..aee5ce471eba 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c @@ -2589,6 +2589,8 @@ void mlx5_lag_disable_change(struct mlx5_core_dev *dev) mpesw = ldev->mode == MLX5_LAG_MODE_MPESW; if (mpesw) mlx5_mpesw_sd_devcoms_lock(ldev); + else if (sd_devcom) + mlx5_devcom_comp_lock(sd_devcom); mutex_lock(&ldev->lock); ldev->mode_changes_in_progress++; @@ -2599,26 +2601,22 @@ void mlx5_lag_disable_change(struct mlx5_core_dev *dev) mlx5_disable_lag(ldev); } + if (sd_devcom) { + mlx5_lag_for_each(i, 0, ldev, MLX5_LAG_FILTER_ALL) { + pf = mlx5_lag_pf(ldev, i); + if (pf->dev == dev && pf->sd_fdb_active) { + mlx5_lag_shared_fdb_destroy(ldev, pf->group_id); + break; + } + } + } + mutex_unlock(&ldev->lock); if (mpesw) mlx5_mpesw_sd_devcoms_unlock(ldev); + else if (sd_devcom) + mlx5_devcom_comp_unlock(sd_devcom); mlx5_devcom_comp_unlock(primary->priv.hca_devcom_comp); - - if (!sd_devcom) - return; - - /* Teardown SD shared FDB for this device's group if active */ - mlx5_devcom_comp_lock(sd_devcom); - mutex_lock(&ldev->lock); - mlx5_lag_for_each(i, 0, ldev, MLX5_LAG_FILTER_ALL) { - pf = mlx5_lag_pf(ldev, i); - if (pf->dev == dev && pf->sd_fdb_active) { - mlx5_lag_shared_fdb_destroy(ldev, pf->group_id); - break; - } - } - mutex_unlock(&ldev->lock); - mlx5_devcom_comp_unlock(sd_devcom); } void mlx5_lag_enable_change(struct mlx5_core_dev *dev) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c index 4cdc50cd6f03..99cf455a61e1 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c @@ -345,7 +345,14 @@ static void sd_lag_init(struct mlx5_core_dev *dev) return; } +recheck: mutex_lock(&ldev->lock); + if (ldev->mode_changes_in_progress) { + mutex_unlock(&ldev->lock); + msleep(100); + goto recheck; + } + pf = mlx5_lag_pf_by_dev(ldev, primary); if (!pf) { sd_warn(primary, "%s: primary not registered in ldev, skipping\n", @@ -388,7 +395,13 @@ static void sd_lag_cleanup(struct mlx5_core_dev *dev) if (!ldev) return; +recheck: mutex_lock(&ldev->lock); + if (ldev->mode_changes_in_progress) { + mutex_unlock(&ldev->lock); + msleep(100); + goto recheck; + } mlx5_sd_for_each_secondary(i, primary, pos) mlx5_ldev_remove_mdev(ldev, pos); -- 2.44.0