From patchwork Wed Feb 26 17:47:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Taehee Yoo X-Patchwork-Id: 1245244 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=g9v/jtOm; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48SNYJ3lsmz9sPK for ; Thu, 27 Feb 2020 04:47:32 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726907AbgBZRrb (ORCPT ); Wed, 26 Feb 2020 12:47:31 -0500 Received: from mail-pf1-f194.google.com ([209.85.210.194]:34858 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726631AbgBZRrb (ORCPT ); Wed, 26 Feb 2020 12:47:31 -0500 Received: by mail-pf1-f194.google.com with SMTP id i19so149624pfa.2 for ; Wed, 26 Feb 2020 09:47:30 -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=YEewmmjg9L6uxTVzMfgFdNq1SumNAZgvtgHvnTSy5BQ=; b=g9v/jtOmWDbB8djivVMx/j25Izks1Gf+s2Ov3R1aNKfBseOYEujh/GU7gwRNMaedJo KtH6z5jLPofXpMeQF6E33z6YIj+FBJ4zGztx6WjgZv3056ZiA3AAY0lMQDr7bTmaCoJ4 0NDA2P091cmHu5MCJUO6713QfSgvuUkAq9nkCHNia0I9gcePVi0C5uiDSHeJ36y3A+Op ljbo+ivvfxOMy2gvkSXDWFX+DxEud2r3QM1UsXou4k4OOKMhf0YcxQwzyYMAOx4sKVr4 tVMs/HiT2ZTUZsSLQOALmDbALcFC6JfPRNETanVJO/c63p23Us5O8t4zFpzaG/h4N9DS tH/g== 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=YEewmmjg9L6uxTVzMfgFdNq1SumNAZgvtgHvnTSy5BQ=; b=cSaupw5hFG6yAfCDb39AEjGRRBI/OahD0yQmbZBGg7E240fVofpjS6zujCn1wxlkMo tlIbZDvDsqW/Y0xqSAhvwvtfTnWi8jGy4mlt24ztOZevI7Qe0OzvcKstLWWqHrXCwR3P DHo2ztGYSCatkQu0g7rD2YZ7lpXeAhiI2Bt5mND3XhhNsWs0Toj0pfCC+D8lIXw2KTAw 55c57Ba786DCRK7k/jFrIG1bFq5gWEMx4hx33sPxmKwlpMFBeEPg9p5XSh4UJgujytzv FxfAKGnO9JdAHQ6YI8FKrDapadAyRFsAp0r/A2kpOZZdYtORwzmKzyMjo/HEEznx3sBH gmVw== X-Gm-Message-State: APjAAAW1Zbl1ypjYulnGQRofnG/7l5bO2A2N6ah+slMqWkLmverFn69K ni04/wBXewfwPMv1l8qxmds= X-Google-Smtp-Source: APXvYqxJmpqaEFJx1dcmMxoe8Q7aRKP5zYU5eUsuat6r+F5eub33v3OEf5JO+gHiYlmuu0PFdKjL+w== X-Received: by 2002:a65:6090:: with SMTP id t16mr42124pgu.2.1582739249615; Wed, 26 Feb 2020 09:47:29 -0800 (PST) Received: from localhost.localdomain ([180.70.143.152]) by smtp.gmail.com with ESMTPSA id o6sm4050442pfg.180.2020.02.26.09.47.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Feb 2020 09:47:28 -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 05/10] net: rmnet: remove rcu_read_lock in rmnet_force_unassociate_device() Date: Wed, 26 Feb 2020 17:47:23 +0000 Message-Id: <20200226174723.5492-1-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: 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 del dummy0 Splat looks like: [ 128.764922][ T979] WARNING: suspicious RCU usage [ 128.766356][ T979] 5.5.0+ #416 Not tainted [ 128.767667][ T979] ----------------------------- [ 128.769008][ T979] ./include/linux/rcupdate.h:273 Illegal context switch in RCU read-side critical section! [ 128.771375][ T979] [ 128.771375][ T979] other info that might help us debug this: [ 128.771375][ T979] [ 128.773998][ T979] [ 128.773998][ T979] rcu_scheduler_active = 2, debug_locks = 1 [ 128.775572][ T979] 2 locks held by ip/979: [ 128.776507][ T979] #0: ffffffff9ccf6230 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x457/0x890 [ 128.778241][ T979] #1: ffffffff9c9254c0 (rcu_read_lock){....}, at: rmnet_config_notify_cb+0xf0/0x590 [rmnet] [ 128.779704][ T979] [ 128.779704][ T979] stack backtrace: [ 128.780699][ T979] CPU: 0 PID: 979 Comm: ip Not tainted 5.5.0+ #416 [ 128.781763][ T979] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 128.783433][ T979] Call Trace: [ 128.783919][ T979] dump_stack+0x96/0xdb [ 128.784535][ T979] ___might_sleep+0x345/0x440 [ 128.785216][ T979] synchronize_net+0x18/0x30 [ 128.785868][ T979] netdev_rx_handler_unregister+0x40/0xb0 [ 128.786536][ T979] rmnet_unregister_real_device+0x42/0xb0 [rmnet] [ 128.787219][ T979] rmnet_config_notify_cb+0x1f7/0x590 [rmnet] [ 128.787859][ T979] ? rmnet_unregister_bridge.isra.6+0xf0/0xf0 [rmnet] [ 128.788668][ T979] ? rmnet_unregister_bridge.isra.6+0xf0/0xf0 [rmnet] [ 128.789347][ T979] ? __module_text_address+0x13/0x140 [ 128.789853][ T979] notifier_call_chain+0x90/0x160 [ 128.790353][ T979] rollback_registered_many+0x660/0xcf0 [ 128.790877][ T979] ? netif_set_real_num_tx_queues+0x780/0x780 [ 128.791452][ T979] ? __lock_acquire+0xdfe/0x3de0 [ 128.791926][ T979] ? memset+0x1f/0x40 [ 128.792309][ T979] ? __nla_validate_parse+0x98/0x1ab0 [ 128.793033][ T979] unregister_netdevice_many.part.134+0x13/0x1b0 [ 128.794060][ T979] rtnl_delete_link+0xbc/0x100 [ ... ] Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation") Signed-off-by: Taehee Yoo --- 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 93642cdd3305..c8b1bfe127ac 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);