From patchwork Thu Feb 7 19:07:07 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 10801945 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2E4CC746 for ; Thu, 7 Feb 2019 19:09:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A6A52DDB9 for ; Thu, 7 Feb 2019 19:09:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0E44F2DDC1; Thu, 7 Feb 2019 19:09:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 85D822DDB9 for ; Thu, 7 Feb 2019 19:09:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=Ih4bPEbZ2UYurvDDvewm6rgljV/NFQw3P+Kv1foBMyY=; b=qrRWS7isrMffE9qlpx/VUvBjJz qr5uwkdIZWnqK+ol4Kr0jfo/HTCBUWJ0Kv+rvb9bgZZf11TIsVB173l+ytpNDu6x7HBY1Hlnh87gQ EnwnUeGZyI8dEkysPVWCWvIZGjk+KePSnJOo5ICp53CnQas/3JOA6D2boGxlysaQ3CQ/ajICbhfdX 7gAuuYPiLLmAHno7JmiAUtx+WaIGdkmnd29aB7gs/cUd4S4v8HZDBY/fWkRNTLdm9RjYLhpsEB6Mj MhOMhY2YzF3j3zl9NkIGaMjmFY4uC+oWW6OR949rdgCbeFl3nay09fnTcoQo6DKIta3tL5nXC44wD 0PdJmUow==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1grp37-00024B-Sv; Thu, 07 Feb 2019 19:09:25 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1grp2W-0001VE-CK for linux-arm-kernel@lists.infradead.org; Thu, 07 Feb 2019 19:08:54 +0000 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6737737EE7; Thu, 7 Feb 2019 19:08:47 +0000 (UTC) Received: from llong.com (dhcp-17-35.bos.redhat.com [10.18.17.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id 550C262FA3; Thu, 7 Feb 2019 19:08:45 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon , Thomas Gleixner Subject: [PATCH-tip 03/22] locking/rwsem: Relocate rwsem_down_read_failed() Date: Thu, 7 Feb 2019 14:07:07 -0500 Message-Id: <1549566446-27967-4-git-send-email-longman@redhat.com> In-Reply-To: <1549566446-27967-1-git-send-email-longman@redhat.com> References: <1549566446-27967-1-git-send-email-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 07 Feb 2019 19:08:48 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190207_110848_762252_B5EB0F00 X-CRM114-Status: GOOD ( 19.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-xtensa@linux-xtensa.org, Davidlohr Bueso , linux-ia64@vger.kernel.org, Tim Chen , Arnd Bergmann , linux-sh@vger.kernel.org, linux-hexagon@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Linus Torvalds , Borislav Petkov , linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org, Waiman Long , Andrew Morton , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The rwsem_down_read_failed*() functions were relocted from above the optimistic spinning section to below that section. This enables the reader functions to use optimisitic spinning in future patches. There is no code change. Signed-off-by: Waiman Long --- kernel/locking/rwsem-xadd.c | 172 ++++++++++++++++++++++---------------------- 1 file changed, 86 insertions(+), 86 deletions(-) diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index fbe9634..0d518b5 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -225,92 +225,6 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem, } /* - * Wait for the read lock to be granted - */ -static inline struct rw_semaphore __sched * -__rwsem_down_read_failed_common(struct rw_semaphore *sem, int state) -{ - long count, adjustment = -RWSEM_ACTIVE_READ_BIAS; - struct rwsem_waiter waiter; - DEFINE_WAKE_Q(wake_q); - - waiter.task = current; - waiter.type = RWSEM_WAITING_FOR_READ; - - raw_spin_lock_irq(&sem->wait_lock); - if (list_empty(&sem->wait_list)) { - /* - * In case the wait queue is empty and the lock isn't owned - * by a writer, this reader can exit the slowpath and return - * immediately as its RWSEM_ACTIVE_READ_BIAS has already - * been set in the count. - */ - if (atomic_long_read(&sem->count) >= 0) { - raw_spin_unlock_irq(&sem->wait_lock); - return sem; - } - adjustment += RWSEM_WAITING_BIAS; - } - list_add_tail(&waiter.list, &sem->wait_list); - - /* we're now waiting on the lock, but no longer actively locking */ - count = atomic_long_add_return(adjustment, &sem->count); - - /* - * If there are no active locks, wake the front queued process(es). - * - * If there are no writers and we are first in the queue, - * wake our own waiter to join the existing active readers ! - */ - if (count == RWSEM_WAITING_BIAS || - (count > RWSEM_WAITING_BIAS && - adjustment != -RWSEM_ACTIVE_READ_BIAS)) - __rwsem_mark_wake(sem, RWSEM_WAKE_ANY, &wake_q); - - raw_spin_unlock_irq(&sem->wait_lock); - wake_up_q(&wake_q); - - /* wait to be given the lock */ - while (true) { - set_current_state(state); - if (!waiter.task) - break; - if (signal_pending_state(state, current)) { - raw_spin_lock_irq(&sem->wait_lock); - if (waiter.task) - goto out_nolock; - raw_spin_unlock_irq(&sem->wait_lock); - break; - } - schedule(); - } - - __set_current_state(TASK_RUNNING); - return sem; -out_nolock: - list_del(&waiter.list); - if (list_empty(&sem->wait_list)) - atomic_long_add(-RWSEM_WAITING_BIAS, &sem->count); - raw_spin_unlock_irq(&sem->wait_lock); - __set_current_state(TASK_RUNNING); - return ERR_PTR(-EINTR); -} - -__visible struct rw_semaphore * __sched -rwsem_down_read_failed(struct rw_semaphore *sem) -{ - return __rwsem_down_read_failed_common(sem, TASK_UNINTERRUPTIBLE); -} -EXPORT_SYMBOL(rwsem_down_read_failed); - -__visible struct rw_semaphore * __sched -rwsem_down_read_failed_killable(struct rw_semaphore *sem) -{ - return __rwsem_down_read_failed_common(sem, TASK_KILLABLE); -} -EXPORT_SYMBOL(rwsem_down_read_failed_killable); - -/* * This function must be called with the sem->wait_lock held to prevent * race conditions between checking the rwsem wait list and setting the * sem->count accordingly. @@ -505,6 +419,92 @@ static inline bool rwsem_has_spinner(struct rw_semaphore *sem) #endif /* + * Wait for the read lock to be granted + */ +static inline struct rw_semaphore __sched * +__rwsem_down_read_failed_common(struct rw_semaphore *sem, int state) +{ + long count, adjustment = -RWSEM_ACTIVE_READ_BIAS; + struct rwsem_waiter waiter; + DEFINE_WAKE_Q(wake_q); + + waiter.task = current; + waiter.type = RWSEM_WAITING_FOR_READ; + + raw_spin_lock_irq(&sem->wait_lock); + if (list_empty(&sem->wait_list)) { + /* + * In case the wait queue is empty and the lock isn't owned + * by a writer, this reader can exit the slowpath and return + * immediately as its RWSEM_ACTIVE_READ_BIAS has already + * been set in the count. + */ + if (atomic_long_read(&sem->count) >= 0) { + raw_spin_unlock_irq(&sem->wait_lock); + return sem; + } + adjustment += RWSEM_WAITING_BIAS; + } + list_add_tail(&waiter.list, &sem->wait_list); + + /* we're now waiting on the lock, but no longer actively locking */ + count = atomic_long_add_return(adjustment, &sem->count); + + /* + * If there are no active locks, wake the front queued process(es). + * + * If there are no writers and we are first in the queue, + * wake our own waiter to join the existing active readers ! + */ + if (count == RWSEM_WAITING_BIAS || + (count > RWSEM_WAITING_BIAS && + adjustment != -RWSEM_ACTIVE_READ_BIAS)) + __rwsem_mark_wake(sem, RWSEM_WAKE_ANY, &wake_q); + + raw_spin_unlock_irq(&sem->wait_lock); + wake_up_q(&wake_q); + + /* wait to be given the lock */ + while (true) { + set_current_state(state); + if (!waiter.task) + break; + if (signal_pending_state(state, current)) { + raw_spin_lock_irq(&sem->wait_lock); + if (waiter.task) + goto out_nolock; + raw_spin_unlock_irq(&sem->wait_lock); + break; + } + schedule(); + } + + __set_current_state(TASK_RUNNING); + return sem; +out_nolock: + list_del(&waiter.list); + if (list_empty(&sem->wait_list)) + atomic_long_add(-RWSEM_WAITING_BIAS, &sem->count); + raw_spin_unlock_irq(&sem->wait_lock); + __set_current_state(TASK_RUNNING); + return ERR_PTR(-EINTR); +} + +__visible struct rw_semaphore * __sched +rwsem_down_read_failed(struct rw_semaphore *sem) +{ + return __rwsem_down_read_failed_common(sem, TASK_UNINTERRUPTIBLE); +} +EXPORT_SYMBOL(rwsem_down_read_failed); + +__visible struct rw_semaphore * __sched +rwsem_down_read_failed_killable(struct rw_semaphore *sem) +{ + return __rwsem_down_read_failed_common(sem, TASK_KILLABLE); +} +EXPORT_SYMBOL(rwsem_down_read_failed_killable); + +/* * Wait until we successfully acquire the write lock */ static inline struct rw_semaphore *