From patchwork Thu Feb 27 12:25:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Taehee Yoo X-Patchwork-Id: 1245798 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=Dz5fMNuD; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48SsM02mQLz9sNg for ; Thu, 27 Feb 2020 23:25:16 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729032AbgB0MZP (ORCPT ); Thu, 27 Feb 2020 07:25:15 -0500 Received: from mail-pl1-f196.google.com ([209.85.214.196]:41973 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728953AbgB0MZP (ORCPT ); Thu, 27 Feb 2020 07:25:15 -0500 Received: by mail-pl1-f196.google.com with SMTP id t14so1075517plr.8 for ; Thu, 27 Feb 2020 04:25:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=ZIJrbIPHhoUosDBOu3/ZLx+q8DHFQiwD2Y9ezIJ9cPo=; b=Dz5fMNuDTdy8V52GKv3ESPHA2eSLGM407MrSxKYSFLp3yMh/4JLDNyd1UFbcnO5dhd 28Yp7qWcNl72aoh8/Fm2Mzcba8M+YkssElZ2Vz+zEp63ZjDujV+MOysPaAmjrOChuUX1 SrX2RqAbob74FSRJSnxJkr8wYbanCOBMarZRFBipZ0ErZtGcxlgIeoNEL2WinZRxwOdR PGJ+x76/skYKV4msauJ7VV1CXF+c/NrZzXcOsfu2KuV8dJc2CUNcN0Q4SoDWNkl///4E opTF4AnxE2ko52jQCVh5Q3QjMPxvUGZxRSifPajdixh6YoelkURT0O8g8JZmobXMG5KU EiOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=ZIJrbIPHhoUosDBOu3/ZLx+q8DHFQiwD2Y9ezIJ9cPo=; b=ibrfbxOkDJVC1FnE49kxGrMxY3N+od7AMOWIgfM0W7fCMiWSeYj3R4iqavcPwrroLc SZ50R2u1Lv5l4+w5Pz7b2znNJfOTCyQpFGlG6rB2+nPqjsEczGlWBjHyCiahFumBhosS BgwjULGtxuTJKmQtCTy2RL7Lfy8nqyAoGQAIpvee+y1/rzTFu2/qqKaGYMndHVmo1L98 LSHcKVVlNXHC713TsIpnZRyqPcTAL3OJ9xS+2nIO1r8YMEurAxc6HUh5C6FZJ2690oq3 xiRrOSLIuchG5CinMyN9xur5ItynE6IvWZfI4y33aBtg9/QVpj3wZT8vcGoM+DiHCVYa 1w5Q== X-Gm-Message-State: APjAAAVtmVINIU4oKgvF9uiPGXSNA3a2sr090f3bNIKc3ZT+oDpnypW4 T7k7gie0EMtamwDuSucDpzc= X-Google-Smtp-Source: APXvYqzxn6DCRMs4gF4NNDBq484Jbk9pFipuTX8RJyqI2C38VyDPgIXzIKJ5aWuTJVw0bsE5PYTFNg== X-Received: by 2002:a17:902:aa05:: with SMTP id be5mr4187497plb.142.1582806313366; Thu, 27 Feb 2020 04:25:13 -0800 (PST) Received: from localhost.localdomain ([180.70.143.152]) by smtp.gmail.com with ESMTPSA id d1sm6394615pgj.79.2020.02.27.04.25.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2020 04:25:12 -0800 (PST) From: Taehee Yoo To: davem@davemloft.net, kuba@kernel.org, subashab@codeaurora.org, stranche@codeaurora.org, netdev@vger.kernel.org Cc: ap420073@gmail.com Subject: [PATCH net v2 4/8] net: rmnet: remove rcu_read_lock in rmnet_force_unassociate_device() Date: Thu, 27 Feb 2020 12:25:05 +0000 Message-Id: <20200227122505.19262-1-ap420073@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The notifier_call() of the slave interface removes rmnet interface with unregister_netdevice_queue(). But, before calling unregister_netdevice_queue(), it acquires rcu readlock. In the RCU critical section, sleeping isn't be allowed. But, unregister_netdevice_queue() internally calls synchronize_net(), which would sleep. So, suspicious RCU usage warning occurs. Test commands: modprobe rmnet ip link add dummy0 type dummy ip link add dummy1 type dummy ip link add rmnet0 link dummy0 type rmnet mux_id 1 ip link set dummy1 master rmnet0 ip link del dummy0 Splat looks like: [ 79.639245][ T1195] ============================= [ 79.640134][ T1195] WARNING: suspicious RCU usage [ 79.640852][ T1195] 5.6.0-rc1+ #447 Not tainted [ 79.641657][ T1195] ----------------------------- [ 79.642472][ T1195] ./include/linux/rcupdate.h:273 Illegal context switch in RCU read-side critical section! [ 79.644043][ T1195] [ 79.644043][ T1195] other info that might help us debug this: [ 79.644043][ T1195] [ 79.645682][ T1195] [ 79.645682][ T1195] rcu_scheduler_active = 2, debug_locks = 1 [ 79.646980][ T1195] 2 locks held by ip/1195: [ 79.647629][ T1195] #0: ffffffffa3cf64f0 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x457/0x890 [ 79.649312][ T1195] #1: ffffffffa39256c0 (rcu_read_lock){....}, at: rmnet_config_notify_cb+0xf0/0x590 [rmnet] [ 79.651717][ T1195] [ 79.651717][ T1195] stack backtrace: [ 79.652650][ T1195] CPU: 3 PID: 1195 Comm: ip Not tainted 5.6.0-rc1+ #447 [ 79.653702][ T1195] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 79.655037][ T1195] Call Trace: [ 79.655560][ T1195] dump_stack+0x96/0xdb [ 79.656252][ T1195] ___might_sleep+0x345/0x440 [ 79.656994][ T1195] synchronize_net+0x18/0x30 [ 79.661132][ T1195] netdev_rx_handler_unregister+0x40/0xb0 [ 79.666266][ T1195] rmnet_unregister_real_device+0x42/0xb0 [rmnet] [ 79.667211][ T1195] rmnet_config_notify_cb+0x1f7/0x590 [rmnet] [ 79.668121][ T1195] ? rmnet_unregister_bridge.isra.6+0xf0/0xf0 [rmnet] [ 79.669166][ T1195] ? rmnet_unregister_bridge.isra.6+0xf0/0xf0 [rmnet] [ 79.670286][ T1195] ? __module_text_address+0x13/0x140 [ 79.671139][ T1195] notifier_call_chain+0x90/0x160 [ 79.671973][ T1195] rollback_registered_many+0x660/0xcf0 [ 79.672893][ T1195] ? netif_set_real_num_tx_queues+0x780/0x780 [ 79.675091][ T1195] ? __lock_acquire+0xdfe/0x3de0 [ 79.675825][ T1195] ? memset+0x1f/0x40 [ 79.676367][ T1195] ? __nla_validate_parse+0x98/0x1ab0 [ 79.677290][ T1195] unregister_netdevice_many.part.133+0x13/0x1b0 [ 79.678163][ T1195] rtnl_delete_link+0xbc/0x100 [ ... ] Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation") Signed-off-by: Taehee Yoo --- v1 -> v2: - update commit log. drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c index fc68ecdd804b..0ad64aa66592 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c @@ -230,7 +230,6 @@ static void rmnet_force_unassociate_device(struct net_device *dev) port = rmnet_get_port_rtnl(dev); - rcu_read_lock(); rmnet_unregister_bridge(dev, port); hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) { @@ -241,7 +240,6 @@ static void rmnet_force_unassociate_device(struct net_device *dev) kfree(ep); } - rcu_read_unlock(); unregister_netdevice_many(&list); rmnet_unregister_real_device(real_dev, port);