From mboxrd@z Thu Jan 1 00:00:00 1970 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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 6EAB4C4361B for ; Wed, 9 Dec 2020 18:42:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1ACC023101 for ; Wed, 9 Dec 2020 18:42:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733293AbgLISmM (ORCPT ); Wed, 9 Dec 2020 13:42:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732961AbgLISjb (ORCPT ); Wed, 9 Dec 2020 13:39:31 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A84B6C061793; Wed, 9 Dec 2020 10:38:50 -0800 (PST) Date: Wed, 09 Dec 2020 18:38:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1607539128; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HCHLpzsf+qtSYP5Z/O54VFcXA3bDvoqQyI7mhQmeTKc=; b=WF05ShpGIjiZJ+JI6srxt4K4E7W9Mu/tZEyFOt6mkyE33/b0I2SXS0Snu2kKZT51YYEnc1 8XlIknHzJCGxDngm9QJTXQYZdC9naNlD1psU3ARhWamaOqBNF0S4dTOO/1lgIzDBDE3YnB 477RXEA/zTcwNaECsOKHlVnrB2S+Z6hPMEknnsFKjOBKhifKuR7cia9Q7Ff+yTuWxRvb62 Bs0Cc0o/ANlGeaxDhLU4UNYVl1UkR5fV++ZsfNOmQkrnyocb4Yd3/QFmKrwWliKwJEIuqT CQQqiEb71lzSnBbSd62fGJ+6Rk00zRaC/6ttF3SRv4C9/k/urtj6yzBXuckSxA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1607539128; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HCHLpzsf+qtSYP5Z/O54VFcXA3bDvoqQyI7mhQmeTKc=; b=2LUzseco1rMfLByyqmWGYHxtujJM9R92Ha7WkUxFUQqPi9w14fK3twWELdcMREZ64nkeqd rv8OvpJ3Zlim+eBg== From: "tip-bot2 for Waiman Long" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/rwsem: Pass the current atomic count to rwsem_down_read_slowpath() Cc: Waiman Long , "Peter Zijlstra (Intel)" , Davidlohr Bueso , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20201121041416.12285-2-longman@redhat.com> References: <20201121041416.12285-2-longman@redhat.com> MIME-Version: 1.0 Message-ID: <160753912803.3364.4437531645113964830.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/core branch of tip: Commit-ID: c8fe8b0564388f41147326f31e4587171aacccd4 Gitweb: https://git.kernel.org/tip/c8fe8b0564388f41147326f31e4587171aacccd4 Author: Waiman Long AuthorDate: Fri, 20 Nov 2020 23:14:12 -05:00 Committer: Peter Zijlstra CommitterDate: Wed, 09 Dec 2020 17:08:47 +01:00 locking/rwsem: Pass the current atomic count to rwsem_down_read_slowpath() The atomic count value right after reader count increment can be useful to determine the rwsem state at trylock time. So the count value is passed down to rwsem_down_read_slowpath() to be used when appropriate. Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Davidlohr Bueso Link: https://lkml.kernel.org/r/20201121041416.12285-2-longman@redhat.com --- kernel/locking/rwsem.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 67ae366..5768b90 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -270,14 +270,14 @@ static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem) owner | RWSEM_NONSPINNABLE)); } -static inline bool rwsem_read_trylock(struct rw_semaphore *sem) +static inline bool rwsem_read_trylock(struct rw_semaphore *sem, long *cntp) { - long cnt = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count); + *cntp = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count); - if (WARN_ON_ONCE(cnt < 0)) + if (WARN_ON_ONCE(*cntp < 0)) rwsem_set_nonspinnable(sem); - if (!(cnt & RWSEM_READ_FAILED_MASK)) { + if (!(*cntp & RWSEM_READ_FAILED_MASK)) { rwsem_set_reader_owned(sem); return true; } @@ -1008,9 +1008,9 @@ rwsem_spin_on_owner(struct rw_semaphore *sem, unsigned long nonspinnable) * Wait for the read lock to be granted */ static struct rw_semaphore __sched * -rwsem_down_read_slowpath(struct rw_semaphore *sem, int state) +rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, int state) { - long count, adjustment = -RWSEM_READER_BIAS; + long adjustment = -RWSEM_READER_BIAS; struct rwsem_waiter waiter; DEFINE_WAKE_Q(wake_q); bool wake = false; @@ -1356,8 +1356,10 @@ static struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem) */ static inline int __down_read_common(struct rw_semaphore *sem, int state) { - if (!rwsem_read_trylock(sem)) { - if (IS_ERR(rwsem_down_read_slowpath(sem, state))) + long count; + + if (!rwsem_read_trylock(sem, &count)) { + if (IS_ERR(rwsem_down_read_slowpath(sem, count, state))) return -EINTR; DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem); }