From patchwork Tue Jan 26 04:09:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xie He X-Patchwork-Id: 371206 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93263C43381 for ; Tue, 26 Jan 2021 05:41:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4ECFA2223D for ; Tue, 26 Jan 2021 05:41:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731342AbhAZFk4 (ORCPT ); Tue, 26 Jan 2021 00:40:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726241AbhAZELG (ORCPT ); Mon, 25 Jan 2021 23:11:06 -0500 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBE79C061756; Mon, 25 Jan 2021 20:09:46 -0800 (PST) Received: by mail-pf1-x431.google.com with SMTP id m6so9773942pfk.1; Mon, 25 Jan 2021 20:09:46 -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:mime-version :content-transfer-encoding; bh=Lb6PGJRRndY2n4WR7Lpa5cln1ecPc6FokNDfe/2KF6g=; b=LLvp2+HaqLZY0/yagHKDYQgK3MIMDo8k3lGxfrlBrelusl87H4HMSa4zAzC6mzoWP+ tijvQBniDHdL8USYdNvIKEP7GP0tZ36XDBfwR36UatDm1zuZRc2dBORIYR0rwqimD8DN kNFmWPpdHSxQBYPnCVwPBB4SnrdLKm32ovQMFKhXW+LofRxNmXoO6tNf/GaA7wdel1Gh eXhKX9lxGypcuqWaBrtnCzcaf3tfcjGRd7tx1RC0bvTudKpYOjYRFQhP91K9sJ1o0D4Q C5adR/bHF+S0ItqYuvIMusGCr06IbCjST1oJWH00hbCwGnX9rq8K5DUS66q8g/ylKSFp 9Urg== 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:mime-version :content-transfer-encoding; bh=Lb6PGJRRndY2n4WR7Lpa5cln1ecPc6FokNDfe/2KF6g=; b=kBsh7OCOiPhgIVVy8eeWRQn9PrIlCMwvNqOXElGTVcgMJbWLwcuMegQqdcIMKgura+ LrSi/9yrngcZwmJtzGK0R6tutS6Au9fzO30pLbsA4As/UePNuevvYnjUJOQqCrd9vTSV nYltnpvq5QNePyoOQ985NMjs4BdTIvYsudEyR8lUvKVUVFEDRg//Gew66YWdccpuWE1n Hlh7oTueuOwPYUIY3Z4XOkOVnLWMmf5ylsVzYse4PBIEgZ41Nu3tLgtdJwpZkIlPQCjW waYgh52ekFmUqsaV7QGAhwwgkDBPXS4RC5/qa+Uh/+4HyM14g1EpGK5wszSwMrl6ekA+ gwFg== X-Gm-Message-State: AOAM531akKjflXXgFWr7/dSa09A0dWlB6dnxsSnXnYmrd/JYiMxrffGe oEKiIpu5m0valm0DRfTMsKfCF2/ohvY= X-Google-Smtp-Source: ABdhPJzsCrTwlBJNisEODt5V1uwnxTn/FAiHNtfDg3jHazplF2bt1hRY3GU77IaRTCkaxoRthyzBLg== X-Received: by 2002:a63:4e5f:: with SMTP id o31mr3799965pgl.55.1611634186488; Mon, 25 Jan 2021 20:09:46 -0800 (PST) Received: from shane-XPS-13-9380.hsd1.ca.comcast.net ([2601:646:8800:1c00:9f6e:d4d0:4340:ac58]) by smtp.gmail.com with ESMTPSA id m4sm17766342pfa.53.2021.01.25.20.09.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 20:09:45 -0800 (PST) From: Xie He To: "David S. Miller" , Jakub Kicinski , linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Martin Schiller Cc: Xie He Subject: [PATCH net v6] net: lapb: Add locking to the lapb module Date: Mon, 25 Jan 2021 20:09:39 -0800 Message-Id: <20210126040939.69995-1-xie.he.0141@gmail.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In the lapb module, the timers may run concurrently with other code in this module, and there is currently no locking to prevent the code from racing on "struct lapb_cb". This patch adds locking to prevent racing. 1. Add "spinlock_t lock" to "struct lapb_cb"; Add "spin_lock_bh" and "spin_unlock_bh" to APIs, timer functions and notifier functions. 2. Add "bool t1timer_stop, t2timer_stop" to "struct lapb_cb" to make us able to ask running timers to abort; Modify "lapb_stop_t1timer" and "lapb_stop_t2timer" to make them able to abort running timers; Modify "lapb_t2timer_expiry" and "lapb_t1timer_expiry" to make them abort after they are stopped by "lapb_stop_t1timer", "lapb_stop_t2timer", and "lapb_start_t1timer", "lapb_start_t2timer". 3. Let lapb_unregister wait for other API functions and running timers to stop. 4. The lapb_device_event function calls lapb_disconnect_request. In order to avoid trying to hold the lock twice, add a new function named "__lapb_disconnect_request" which assumes the lock is held, and make it called by lapb_disconnect_request and lapb_device_event. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: Martin Schiller Signed-off-by: Xie He --- Change from v5: Add usleep_range to the waiting loop in lapb_unregister. I didn't restore the "goto"s in "__lapb_disconnect_request" because after the function splitting there's nowhere we can "goto" anymore. Change from v4: Make lapb_unregister wait for other refs to "lapb" to drop, to ensure that other LAPB API calls have all finished. Change from v3: In lapb_unregister make sure the self-restarting t1timer has really been stopped. Change from v2: Create a new __lapb_disconnect_request function to reduce redundant code. Change from v1: Break long lines to keep the line lengths within 80 characters. --- include/net/lapb.h | 2 ++ net/lapb/lapb_iface.c | 70 +++++++++++++++++++++++++++++++++---------- net/lapb/lapb_timer.c | 30 ++++++++++++++++--- 3 files changed, 82 insertions(+), 20 deletions(-) diff --git a/include/net/lapb.h b/include/net/lapb.h index ccc3d1f020b0..eee73442a1ba 100644 --- a/include/net/lapb.h +++ b/include/net/lapb.h @@ -92,6 +92,7 @@ struct lapb_cb { unsigned short n2, n2count; unsigned short t1, t2; struct timer_list t1timer, t2timer; + bool t1timer_stop, t2timer_stop; /* Internal control information */ struct sk_buff_head write_queue; @@ -103,6 +104,7 @@ struct lapb_cb { struct lapb_frame frmr_data; unsigned char frmr_type; + spinlock_t lock; refcount_t refcnt; }; diff --git a/net/lapb/lapb_iface.c b/net/lapb/lapb_iface.c index 40961889e9c0..0511bbe4af7b 100644 --- a/net/lapb/lapb_iface.c +++ b/net/lapb/lapb_iface.c @@ -122,6 +122,8 @@ static struct lapb_cb *lapb_create_cb(void) timer_setup(&lapb->t1timer, NULL, 0); timer_setup(&lapb->t2timer, NULL, 0); + lapb->t1timer_stop = true; + lapb->t2timer_stop = true; lapb->t1 = LAPB_DEFAULT_T1; lapb->t2 = LAPB_DEFAULT_T2; @@ -129,6 +131,8 @@ static struct lapb_cb *lapb_create_cb(void) lapb->mode = LAPB_DEFAULT_MODE; lapb->window = LAPB_DEFAULT_WINDOW; lapb->state = LAPB_STATE_0; + + spin_lock_init(&lapb->lock); refcount_set(&lapb->refcnt, 1); out: return lapb; @@ -178,11 +182,23 @@ int lapb_unregister(struct net_device *dev) goto out; lapb_put(lapb); + /* Wait for other refs to "lapb" to drop */ + while (refcount_read(&lapb->refcnt) > 2) + usleep_range(1, 10); + + spin_lock_bh(&lapb->lock); + lapb_stop_t1timer(lapb); lapb_stop_t2timer(lapb); lapb_clear_queues(lapb); + spin_unlock_bh(&lapb->lock); + + /* Wait for running timers to stop */ + del_timer_sync(&lapb->t1timer); + del_timer_sync(&lapb->t2timer); + __lapb_remove_cb(lapb); lapb_put(lapb); @@ -201,6 +217,8 @@ int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms) if (!lapb) goto out; + spin_lock_bh(&lapb->lock); + parms->t1 = lapb->t1 / HZ; parms->t2 = lapb->t2 / HZ; parms->n2 = lapb->n2; @@ -219,6 +237,7 @@ int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms) else parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ; + spin_unlock_bh(&lapb->lock); lapb_put(lapb); rc = LAPB_OK; out: @@ -234,6 +253,8 @@ int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms) if (!lapb) goto out; + spin_lock_bh(&lapb->lock); + rc = LAPB_INVALUE; if (parms->t1 < 1 || parms->t2 < 1 || parms->n2 < 1) goto out_put; @@ -256,6 +277,7 @@ int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms) rc = LAPB_OK; out_put: + spin_unlock_bh(&lapb->lock); lapb_put(lapb); out: return rc; @@ -270,6 +292,8 @@ int lapb_connect_request(struct net_device *dev) if (!lapb) goto out; + spin_lock_bh(&lapb->lock); + rc = LAPB_OK; if (lapb->state == LAPB_STATE_1) goto out_put; @@ -285,24 +309,18 @@ int lapb_connect_request(struct net_device *dev) rc = LAPB_OK; out_put: + spin_unlock_bh(&lapb->lock); lapb_put(lapb); out: return rc; } EXPORT_SYMBOL(lapb_connect_request); -int lapb_disconnect_request(struct net_device *dev) +static int __lapb_disconnect_request(struct lapb_cb *lapb) { - struct lapb_cb *lapb = lapb_devtostruct(dev); - int rc = LAPB_BADTOKEN; - - if (!lapb) - goto out; - switch (lapb->state) { case LAPB_STATE_0: - rc = LAPB_NOTCONNECTED; - goto out_put; + return LAPB_NOTCONNECTED; case LAPB_STATE_1: lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev); @@ -310,12 +328,10 @@ int lapb_disconnect_request(struct net_device *dev) lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND); lapb->state = LAPB_STATE_0; lapb_start_t1timer(lapb); - rc = LAPB_NOTCONNECTED; - goto out_put; + return LAPB_NOTCONNECTED; case LAPB_STATE_2: - rc = LAPB_OK; - goto out_put; + return LAPB_OK; } lapb_clear_queues(lapb); @@ -328,8 +344,22 @@ int lapb_disconnect_request(struct net_device *dev) lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev); lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev); - rc = LAPB_OK; -out_put: + return LAPB_OK; +} + +int lapb_disconnect_request(struct net_device *dev) +{ + struct lapb_cb *lapb = lapb_devtostruct(dev); + int rc = LAPB_BADTOKEN; + + if (!lapb) + goto out; + + spin_lock_bh(&lapb->lock); + + rc = __lapb_disconnect_request(lapb); + + spin_unlock_bh(&lapb->lock); lapb_put(lapb); out: return rc; @@ -344,6 +374,8 @@ int lapb_data_request(struct net_device *dev, struct sk_buff *skb) if (!lapb) goto out; + spin_lock_bh(&lapb->lock); + rc = LAPB_NOTCONNECTED; if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4) goto out_put; @@ -352,6 +384,7 @@ int lapb_data_request(struct net_device *dev, struct sk_buff *skb) lapb_kick(lapb); rc = LAPB_OK; out_put: + spin_unlock_bh(&lapb->lock); lapb_put(lapb); out: return rc; @@ -364,7 +397,9 @@ int lapb_data_received(struct net_device *dev, struct sk_buff *skb) int rc = LAPB_BADTOKEN; if (lapb) { + spin_lock_bh(&lapb->lock); lapb_data_input(lapb, skb); + spin_unlock_bh(&lapb->lock); lapb_put(lapb); rc = LAPB_OK; } @@ -435,6 +470,8 @@ static int lapb_device_event(struct notifier_block *this, unsigned long event, if (!lapb) return NOTIFY_DONE; + spin_lock_bh(&lapb->lock); + switch (event) { case NETDEV_UP: lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name); @@ -454,7 +491,7 @@ static int lapb_device_event(struct notifier_block *this, unsigned long event, break; case NETDEV_GOING_DOWN: if (netif_carrier_ok(dev)) - lapb_disconnect_request(dev); + __lapb_disconnect_request(lapb); break; case NETDEV_DOWN: lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name); @@ -489,6 +526,7 @@ static int lapb_device_event(struct notifier_block *this, unsigned long event, break; } + spin_unlock_bh(&lapb->lock); lapb_put(lapb); return NOTIFY_DONE; } diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c index baa247fe4ed0..0230b272b7d1 100644 --- a/net/lapb/lapb_timer.c +++ b/net/lapb/lapb_timer.c @@ -40,6 +40,7 @@ void lapb_start_t1timer(struct lapb_cb *lapb) lapb->t1timer.function = lapb_t1timer_expiry; lapb->t1timer.expires = jiffies + lapb->t1; + lapb->t1timer_stop = false; add_timer(&lapb->t1timer); } @@ -50,16 +51,19 @@ void lapb_start_t2timer(struct lapb_cb *lapb) lapb->t2timer.function = lapb_t2timer_expiry; lapb->t2timer.expires = jiffies + lapb->t2; + lapb->t2timer_stop = false; add_timer(&lapb->t2timer); } void lapb_stop_t1timer(struct lapb_cb *lapb) { + lapb->t1timer_stop = true; del_timer(&lapb->t1timer); } void lapb_stop_t2timer(struct lapb_cb *lapb) { + lapb->t2timer_stop = true; del_timer(&lapb->t2timer); } @@ -72,16 +76,31 @@ static void lapb_t2timer_expiry(struct timer_list *t) { struct lapb_cb *lapb = from_timer(lapb, t, t2timer); + spin_lock_bh(&lapb->lock); + if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */ + goto out; + if (lapb->t2timer_stop) /* The timer has been stopped */ + goto out; + if (lapb->condition & LAPB_ACK_PENDING_CONDITION) { lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; lapb_timeout_response(lapb); } + +out: + spin_unlock_bh(&lapb->lock); } static void lapb_t1timer_expiry(struct timer_list *t) { struct lapb_cb *lapb = from_timer(lapb, t, t1timer); + spin_lock_bh(&lapb->lock); + if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */ + goto out; + if (lapb->t1timer_stop) /* The timer has been stopped */ + goto out; + switch (lapb->state) { /* @@ -108,7 +127,7 @@ static void lapb_t1timer_expiry(struct timer_list *t) lapb->state = LAPB_STATE_0; lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev); - return; + goto out; } else { lapb->n2count++; if (lapb->mode & LAPB_EXTENDED) { @@ -132,7 +151,7 @@ static void lapb_t1timer_expiry(struct timer_list *t) lapb->state = LAPB_STATE_0; lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT); lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev); - return; + goto out; } else { lapb->n2count++; lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev); @@ -150,7 +169,7 @@ static void lapb_t1timer_expiry(struct timer_list *t) lapb_stop_t2timer(lapb); lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev); - return; + goto out; } else { lapb->n2count++; lapb_requeue_frames(lapb); @@ -167,7 +186,7 @@ static void lapb_t1timer_expiry(struct timer_list *t) lapb->state = LAPB_STATE_0; lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev); - return; + goto out; } else { lapb->n2count++; lapb_transmit_frmr(lapb); @@ -176,4 +195,7 @@ static void lapb_t1timer_expiry(struct timer_list *t) } lapb_start_t1timer(lapb); + +out: + spin_unlock_bh(&lapb->lock); }