From patchwork Tue Jan 2 03:43:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shifeng Li X-Patchwork-Id: 13508794 Received: from mail-m118196.ym.163.com (mail-m118196.ym.163.com [115.236.118.196]) (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 58CDA20F8; Tue, 2 Jan 2024 03:53:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sangfor.com.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sangfor.com.cn Received: from ubuntu.localdomain (unknown [111.222.250.119]) by mail-m12750.qiye.163.com (Hmail) with ESMTPA id 2C2E2F2038A; Tue, 2 Jan 2024 11:43:57 +0800 (CST) From: Shifeng Li To: jgg@ziepe.ca, leon@kernel.org, wenglianfa@huawei.com, gustavoars@kernel.org Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Shifeng Li , Shifeng Li Subject: [PATCH] RDMA/device: Fix a race between mad_client and cm_client init Date: Mon, 1 Jan 2024 19:43:35 -0800 Message-Id: <20240102034335.34842-1-lishifeng@sangfor.com.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFITzdXWS1ZQUlXWQ8JGhUIEh9ZQVlDTx9CVkpKH0NDHkNJGhhNS1UTARMWGhIXJBQOD1 lXWRgSC1lBWUpKSlVJSUlVSU5LVUpKQllXWRYaDxIVHRRZQVlPS0hVSk1PSUxOVUpLS1VKQktLWQ Y+ X-HM-Tid: 0a8cc8455a43b21dkuuu2c2e2f2038a X-HM-MType: 1 X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6P1E6Vio5NDw8FUkqMD81TTgT LRcKCi1VSlVKTEtPSk1MS0hDS0hNVTMWGhIXVRcSCBMSHR4VHDsIGhUcHRQJVRgUFlUYFUVZV1kS C1lBWUpKSlVJSUlVSU5LVUpKQllXWQgBWUFITUlPNwY+ The mad_client will be initialized in enable_device_and_get(), while the devices_rwsem will be downgraded to a read semaphore. There is a window that leads to the failed initialization for cm_client, since it can not get matched mad port from ib_mad_port_list, and the matched mad port will be added to the list after that. mad_client | cm_client ------------------|-------------------------------------------------------- ib_register_device| enable_device_and_get down_write(&devices_rwsem) xa_set_mark(&devices, DEVICE_REGISTERED) downgrade_write(&devices_rwsem) | |ib_cm_init |ib_register_client(&cm_client) |down_read(&devices_rwsem) |xa_for_each_marked (&devices, DEVICE_REGISTERED) |add_client_context |cm_add_one |ib_register_mad_agent |ib_get_mad_port |__ib_get_mad_port |list_for_each_entry(entry, &ib_mad_port_list, port_list) |return NULL |up_read(&devices_rwsem) | add_client_context| ib_mad_init_device| ib_mad_port_open | list_add_tail(&port_priv->port_list, &ib_mad_port_list) up_read(&devices_rwsem) | Fix it by using the devices_rwsem write semaphore to protect the mad_client init flow in enable_device_and_get(). Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration") Cc: Shifeng Li Signed-off-by: Shifeng Li --- drivers/infiniband/core/device.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c index 67bcea7a153c..85782786993d 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device) down_write(&devices_rwsem); xa_set_mark(&devices, device->index, DEVICE_REGISTERED); - /* - * By using downgrade_write() we ensure that no other thread can clear - * DEVICE_REGISTERED while we are completing the client setup. - */ - downgrade_write(&devices_rwsem); - if (device->ops.enable_driver) { ret = device->ops.enable_driver(device); if (ret) @@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device) if (!ret) ret = add_compat_devs(device); out: - up_read(&devices_rwsem); + up_write(&devices_rwsem); return ret; }