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[81.108.45.148]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4888a705f99sm27380715e9.11.2026.04.01.16.52.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Apr 2026 16:52:57 -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 v4] IB/mlx5: Fix state corruption and resource leaks in loopback enablement Date: Thu, 2 Apr 2026 00:52:32 +0100 Message-ID: <20260401235232.21155-1-prathameshdeshpande7@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260401223550.20040-1-prathameshdeshpande7@gmail.com> References: <20260401223550.20040-1-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 returning 'err' (which is 0) instead of a literal 0. Additionally, as identified by Sashiko, if mlx5_ib_enable_lb() fails to update the hardware, it leaves the software state in an inconsistent state where reference counters are incremented but the hardware remains disabled. Fixing this in the caller created a race window where the mutex was released between enablement and rollback. Update mlx5_ib_enable_lb() to perform an atomic rollback of reference counters and only set the 'enabled' flag if the hardware command succeeds. Also, add error handling in mlx5_ib_alloc_transport_domain() to deallocate the transport domain (tdn) if loopback enablement fails. Signed-off-by: Prathamesh Deshpande --- 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 | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c index 635002e684a5..877b02e98033 100644 --- a/drivers/infiniband/hw/mlx5/main.c +++ b/drivers/infiniband/hw/mlx5/main.c @@ -2022,7 +2022,14 @@ int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp) 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; + } } } @@ -2068,9 +2075,13 @@ 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; - return mlx5_ib_enable_lb(dev, true, false); + err = mlx5_ib_enable_lb(dev, true, false); + if (err) + mlx5_cmd_dealloc_transport_domain(dev->mdev, *tdn, uid); + + return err; } static void mlx5_ib_dealloc_transport_domain(struct mlx5_ib_dev *dev, u32 tdn, -- 2.43.0