From patchwork Thu May 28 12:35:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 11575733 X-Patchwork-Delegate: marcel@holtmann.org Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 82A93166C for ; Thu, 28 May 2020 12:35:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7587220707 for ; Thu, 28 May 2020 12:35:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389793AbgE1MfV convert rfc822-to-8bit (ORCPT ); Thu, 28 May 2020 08:35:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389788AbgE1MfT (ORCPT ); Thu, 28 May 2020 08:35:19 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F205EC05BD1E for ; Thu, 28 May 2020 05:35:18 -0700 (PDT) Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1jeHke-0007NC-Hh; Thu, 28 May 2020 14:35:12 +0200 Date: Thu, 28 May 2020 14:35:12 +0200 From: Sebastian Andrzej Siewior To: kbuild test robot Cc: linux-bluetooth@vger.kernel.org, kbuild-all@lists.01.org, Marcel Holtmann , Johan Hedberg , Thomas Gleixner , "Luis Claudio R . Goncalves" Subject: [PATCH v2] Bluetooth: Acquire sk_lock.slock without disabling interrupts Message-ID: <20200528123512.o32lkytxjdpwzi7r@linutronix.de> References: <20200527193919.1655228-1-bigeasy@linutronix.de> <20200528071103.GA26242@xsang-OptiPlex-9020> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200528071103.GA26242@xsang-OptiPlex-9020> Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org There was a lockdep which led to commit fad003b6c8e3d ("Bluetooth: Fix inconsistent lock state with RFCOMM") Lockdep noticed that `sk->sk_lock.slock' was acquired without disabling the softirq while the lock was also used in softirq context. Unfortunately the solution back then was to disable interrupts before acquiring the lock which however made lockdep happy. It would have been enough to simply disable the softirq. Disabling interrupts before acquiring a spinlock_t is not allowed on PREEMPT_RT because these locks are converted to 'sleeping' spinlocks. Use spin_lock_bh() in order to acquire the `sk_lock.slock'. Reported-by: Luis Claudio R. Goncalves Reported-by: kbuild test robot [missing unlock] Signed-off-by: Sebastian Andrzej Siewior --- v1…v2: Unlock on the way out as reported by the lkp bot. net/bluetooth/rfcomm/sock.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c index b4eaf21360ef2..df14eebe80da8 100644 --- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -64,15 +64,13 @@ static void rfcomm_sk_data_ready(struct rfcomm_dlc *d, struct sk_buff *skb) static void rfcomm_sk_state_change(struct rfcomm_dlc *d, int err) { struct sock *sk = d->owner, *parent; - unsigned long flags; if (!sk) return; BT_DBG("dlc %p state %ld err %d", d, d->state, err); - local_irq_save(flags); - bh_lock_sock(sk); + spin_lock_bh(&sk->sk_lock.slock); if (err) sk->sk_err = err; @@ -93,8 +91,7 @@ static void rfcomm_sk_state_change(struct rfcomm_dlc *d, int err) sk->sk_state_change(sk); } - bh_unlock_sock(sk); - local_irq_restore(flags); + spin_unlock_bh(&sk->sk_lock.slock); if (parent && sock_flag(sk, SOCK_ZAPPED)) { /* We have to drop DLC lock here, otherwise