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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 00452C433ED for ; Mon, 5 Apr 2021 09:02:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF32D60238 for ; Mon, 5 Apr 2021 09:02:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237457AbhDEJC1 (ORCPT ); Mon, 5 Apr 2021 05:02:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:42772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232860AbhDEJAt (ORCPT ); Mon, 5 Apr 2021 05:00:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6399B6124C; Mon, 5 Apr 2021 09:00:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617613243; bh=2q1iU9XeChlMWGNPT1kMFQPoe8xvbCDxHdcqTqfRRI8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lOQc9PT13EEjvcRnYfTgT3je5Mld8V8VLwyjmCEPhAElhz+wWkCjjlvl1rpN7iyXJ 1mS3WA0gU5hZzAbqdAhYmE/IKtWdd8xX6BoSPkfU5tgGnHn3TWyVKIYpxWoes7O2vf CM+oiCTn2a3Ke+5tI3DP5uIDXTeQcHbbF+avMivI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Waiman Long , Ingo Molnar , Davidlohr Bueso , Sasha Levin Subject: [PATCH 4.19 21/56] locking/ww_mutex: Simplify use_ww_ctx & ww_ctx handling Date: Mon, 5 Apr 2021 10:53:52 +0200 Message-Id: <20210405085023.216103525@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210405085022.562176619@linuxfoundation.org> References: <20210405085022.562176619@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Waiman Long [ Upstream commit 5de2055d31ea88fd9ae9709ac95c372a505a60fa ] The use_ww_ctx flag is passed to mutex_optimistic_spin(), but the function doesn't use it. The frequent use of the (use_ww_ctx && ww_ctx) combination is repetitive. In fact, ww_ctx should not be used at all if !use_ww_ctx. Simplify ww_mutex code by dropping use_ww_ctx from mutex_optimistic_spin() an clear ww_ctx if !use_ww_ctx. In this way, we can replace (use_ww_ctx && ww_ctx) by just (ww_ctx). Signed-off-by: Waiman Long Signed-off-by: Ingo Molnar Acked-by: Davidlohr Bueso Link: https://lore.kernel.org/r/20210316153119.13802-2-longman@redhat.com Signed-off-by: Sasha Levin --- kernel/locking/mutex.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 3f8a35104285..b3da782cdfbd 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -609,7 +609,7 @@ static inline int mutex_can_spin_on_owner(struct mutex *lock) */ static __always_inline bool mutex_optimistic_spin(struct mutex *lock, struct ww_acquire_ctx *ww_ctx, - const bool use_ww_ctx, struct mutex_waiter *waiter) + struct mutex_waiter *waiter) { if (!waiter) { /* @@ -685,7 +685,7 @@ fail: #else static __always_inline bool mutex_optimistic_spin(struct mutex *lock, struct ww_acquire_ctx *ww_ctx, - const bool use_ww_ctx, struct mutex_waiter *waiter) + struct mutex_waiter *waiter) { return false; } @@ -905,10 +905,13 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, struct ww_mutex *ww; int ret; + if (!use_ww_ctx) + ww_ctx = NULL; + might_sleep(); ww = container_of(lock, struct ww_mutex, base); - if (use_ww_ctx && ww_ctx) { + if (ww_ctx) { if (unlikely(ww_ctx == READ_ONCE(ww->ctx))) return -EALREADY; @@ -925,10 +928,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip); if (__mutex_trylock(lock) || - mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, NULL)) { + mutex_optimistic_spin(lock, ww_ctx, NULL)) { /* got the lock, yay! */ lock_acquired(&lock->dep_map, ip); - if (use_ww_ctx && ww_ctx) + if (ww_ctx) ww_mutex_set_context_fastpath(ww, ww_ctx); preempt_enable(); return 0; @@ -939,7 +942,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, * After waiting to acquire the wait_lock, try again. */ if (__mutex_trylock(lock)) { - if (use_ww_ctx && ww_ctx) + if (ww_ctx) __ww_mutex_check_waiters(lock, ww_ctx); goto skip_wait; @@ -992,7 +995,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, goto err; } - if (use_ww_ctx && ww_ctx) { + if (ww_ctx) { ret = __ww_mutex_check_kill(lock, &waiter, ww_ctx); if (ret) goto err; @@ -1005,7 +1008,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, * ww_mutex needs to always recheck its position since its waiter * list is not FIFO ordered. */ - if ((use_ww_ctx && ww_ctx) || !first) { + if (ww_ctx || !first) { first = __mutex_waiter_is_first(lock, &waiter); if (first) __mutex_set_flag(lock, MUTEX_FLAG_HANDOFF); @@ -1018,7 +1021,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, * or we must see its unlock and acquire. */ if (__mutex_trylock(lock) || - (first && mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, &waiter))) + (first && mutex_optimistic_spin(lock, ww_ctx, &waiter))) break; spin_lock(&lock->wait_lock); @@ -1027,7 +1030,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, acquired: __set_current_state(TASK_RUNNING); - if (use_ww_ctx && ww_ctx) { + if (ww_ctx) { /* * Wound-Wait; we stole the lock (!first_waiter), check the * waiters as anyone might want to wound us. @@ -1047,7 +1050,7 @@ skip_wait: /* got the lock - cleanup and rejoice! */ lock_acquired(&lock->dep_map, ip); - if (use_ww_ctx && ww_ctx) + if (ww_ctx) ww_mutex_lock_acquired(ww, ww_ctx); spin_unlock(&lock->wait_lock); -- 2.30.1