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[81.108.45.148]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488a3d6944bsm82743405e9.11.2026.04.04.16.08.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 Apr 2026 16:08:34 -0700 (PDT) From: Prathamesh Deshpande To: prathameshdeshpande7@gmail.com Cc: dledford@redhat.com, haggaie@mellanox.com, jgg@ziepe.ca, leon@kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org Subject: [PATCH v6] IB/mlx5: Fix loopback enablement state and resource leaks Date: Sun, 5 Apr 2026 00:07:58 +0100 Message-ID: <20260404230759.15131-1-prathameshdeshpande7@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260404215155.13254-1-prathameshdeshpande7@gmail.com> References: <20260404215155.13254-1-prathameshdeshpande7@gmail.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In mlx5_ib_alloc_transport_domain(), an early success path was incorrectly returning a variable instead of a literal 0. Additionally, the loopback (LB) infrastructure required updates to address initialization and concurrency issues: 1. Initialization: The LB mutex was initialized conditionally, but paths like create_raw_packet_qp_tir() in qp.c call LB functions regardless of those conditions. Move initialization to stage_init_init() to ensure the lock is always valid. 2. State Integrity: Update mlx5_ib_enable_lb() to roll back reference counters if the hardware command fails, ensuring software state matches hardware. 3. Concurrency: Move 'force_enable' checks inside the mutex in both enable/disable paths to prevent potential counter underflows. 4. Resource Leak: Deallocate the transport domain if LB enablement fails in mlx5_ib_alloc_transport_domain(). Signed-off-by: Prathamesh Deshpande --- v6: - Always update software counters regardless of force_enable to prevent underflows during dynamic unbinding [Sashiko]. - Updated disable condition to user_td <= 1 to prevent HW state leaks on systems without transport domains [Sashiko]. - Rebased on rdma/for-next to resolve baseline application failures. v5: - Moved mutex_init to stage_init_init to prevent crashes on non-ETH hardware. - Implemented 'goto unlock' for concurrency safety in enable/disable paths. - Added atomic rollback and fixed tdn leak. v4: - Moved rollback logic into mlx5_ib_enable_lb() to ensure atomicity within the mutex and prevent race conditions [Sashiko]. v3: - Also call mlx5_ib_disable_lb() on failure to roll back software state/counters [Sashiko]. v2: - Added deallocation of tdn if mlx5_ib_enable_lb() fails [Sashiko]. - Reworded commit message to reflect the functional fix and credit the tool. drivers/infiniband/hw/mlx5/main.c | 39 +++++++++++++++++++------------ 1 file changed, 24 insertions(+), 15 deletions(-) diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c index b74bf2697655..c2fafa00b60c 100644 --- a/drivers/infiniband/hw/mlx5/main.c +++ b/drivers/infiniband/hw/mlx5/main.c @@ -2009,23 +2009,31 @@ int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp) { int err = 0; - if (dev->lb.force_enable) - return 0; - mutex_lock(&dev->lb.mutex); if (td) dev->lb.user_td++; if (qp) dev->lb.qps++; - if (dev->lb.user_td == 2 || + if (dev->lb.force_enable) + goto unlock; + + if (dev->lb.user_td == 1 || dev->lb.qps == 1) { if (!dev->lb.enabled) { err = mlx5_nic_vport_update_local_lb(dev->mdev, true); - dev->lb.enabled = true; + if (err) { + if (td) + dev->lb.user_td--; + if (qp) + dev->lb.qps--; + } else { + dev->lb.enabled = true; + } } } +unlock: mutex_unlock(&dev->lb.mutex); return err; @@ -2033,16 +2041,16 @@ int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp) void mlx5_ib_disable_lb(struct mlx5_ib_dev *dev, bool td, bool qp) { + mutex_lock(&dev->lb.mutex); if (dev->lb.force_enable) - return; + goto unlock; - mutex_lock(&dev->lb.mutex); if (td) dev->lb.user_td--; if (qp) dev->lb.qps--; - if (dev->lb.user_td == 1 && + if (dev->lb.user_td <= 1 && dev->lb.qps == 0) { if (dev->lb.enabled) { mlx5_nic_vport_update_local_lb(dev->mdev, false); @@ -2050,6 +2058,7 @@ void mlx5_ib_disable_lb(struct mlx5_ib_dev *dev, bool td, bool qp) } } +unlock: mutex_unlock(&dev->lb.mutex); } @@ -2068,9 +2077,13 @@ static int mlx5_ib_alloc_transport_domain(struct mlx5_ib_dev *dev, u32 *tdn, if ((MLX5_CAP_GEN(dev->mdev, port_type) != MLX5_CAP_PORT_TYPE_ETH) || (!MLX5_CAP_GEN(dev->mdev, disable_local_lb_uc) && !MLX5_CAP_GEN(dev->mdev, disable_local_lb_mc))) - return err; + return 0; + + err = mlx5_ib_enable_lb(dev, true, false); + if (err) + mlx5_cmd_dealloc_transport_domain(dev->mdev, *tdn, uid); - return mlx5_ib_enable_lb(dev, true, false); + return err; } static void mlx5_ib_dealloc_transport_domain(struct mlx5_ib_dev *dev, u32 tdn, @@ -4515,6 +4528,7 @@ static int mlx5_ib_stage_init_init(struct mlx5_ib_dev *dev) mutex_init(&dev->data_direct_lock); INIT_LIST_HEAD(&dev->qp_list); spin_lock_init(&dev->reset_flow_resource_lock); + mutex_init(&dev->lb.mutex); xa_init(&dev->odp_mkeys); xa_init(&dev->sig_mrs); atomic_set(&dev->mkey_var, 0); @@ -4786,11 +4800,6 @@ static int mlx5_ib_stage_caps_init(struct mlx5_ib_dev *dev) if (err) return err; - if ((MLX5_CAP_GEN(dev->mdev, port_type) == MLX5_CAP_PORT_TYPE_ETH) && - (MLX5_CAP_GEN(dev->mdev, disable_local_lb_uc) || - MLX5_CAP_GEN(dev->mdev, disable_local_lb_mc))) - mutex_init(&dev->lb.mutex); - if (MLX5_CAP_GEN_64(dev->mdev, general_obj_types) & MLX5_GENERAL_OBJ_TYPES_CAP_VIRTIO_NET_Q) { err = mlx5_ib_init_var_region(dev); -- 2.43.0