From patchwork Thu Feb 7 19:07:09 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 10801943 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 8ED80746 for ; Thu, 7 Feb 2019 19:09:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7ABE42CD0E for ; Thu, 7 Feb 2019 19:09:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6CC132DD93; Thu, 7 Feb 2019 19:09:20 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CA5E92CD0E for ; Thu, 7 Feb 2019 19:09:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727225AbfBGTJH (ORCPT ); Thu, 7 Feb 2019 14:09:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49980 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726576AbfBGTJG (ORCPT ); Thu, 7 Feb 2019 14:09:06 -0500 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 7044C10F85; Thu, 7 Feb 2019 19:09:05 +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 F0DF061146; Thu, 7 Feb 2019 19:09:00 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, x86@kernel.org, Arnd Bergmann , Borislav Petkov , "H. Peter Anvin" , Davidlohr Bueso , Linus Torvalds , Andrew Morton , Tim Chen , Waiman Long Subject: [PATCH-tip 05/22] locking/rwsem: Move owner setting code from rwsem.c to rwsem.h Date: Thu, 7 Feb 2019 14:07:09 -0500 Message-Id: <1549566446-27967-6-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 [10.5.110.28]); Thu, 07 Feb 2019 19:09:05 +0000 (UTC) Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The setting of owner field is specific to rwsem-xadd code, it is not needed for rwsem-spinlock. This patch moves all the owner setting code closer to the rwsem-xadd fast paths directly within rwsem.h file. For __down_read() and __down_read_killable(), it is assumed that rwsem will be marked as reader-owned when the functions return. That is currently true except in the transient case that the waiter queue just becomes empty. So a rwsem_set_reader_owned() call is added for this case. The __rwsem_set_reader_owned() call in __rwsem_mark_wake() is now necessary. Signed-off-by: Waiman Long --- kernel/locking/rwsem-xadd.c | 6 +++--- kernel/locking/rwsem.c | 19 ++----------------- kernel/locking/rwsem.h | 17 +++++++++++++++-- 3 files changed, 20 insertions(+), 22 deletions(-) diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index 0d518b5..c213869 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -176,9 +176,8 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem, goto try_reader_grant; } /* - * It is not really necessary to set it to reader-owned here, - * but it gives the spinners an early indication that the - * readers now have the lock. + * Set it to reader-owned to give spinners an early + * indication that readers now have the lock. */ __rwsem_set_reader_owned(sem, waiter->task); } @@ -441,6 +440,7 @@ static inline bool rwsem_has_spinner(struct rw_semaphore *sem) */ if (atomic_long_read(&sem->count) >= 0) { raw_spin_unlock_irq(&sem->wait_lock); + rwsem_set_reader_owned(sem); return sem; } adjustment += RWSEM_WAITING_BIAS; diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index e586f0d..59e5848 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -24,7 +24,6 @@ void __sched down_read(struct rw_semaphore *sem) rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_read_trylock, __down_read); - rwsem_set_reader_owned(sem); } EXPORT_SYMBOL(down_read); @@ -39,7 +38,6 @@ int __sched down_read_killable(struct rw_semaphore *sem) return -EINTR; } - rwsem_set_reader_owned(sem); return 0; } @@ -52,10 +50,8 @@ int down_read_trylock(struct rw_semaphore *sem) { int ret = __down_read_trylock(sem); - if (ret == 1) { + if (ret == 1) rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_); - rwsem_set_reader_owned(sem); - } return ret; } @@ -70,7 +66,6 @@ void __sched down_write(struct rw_semaphore *sem) rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_write_trylock, __down_write); - rwsem_set_owner(sem); } EXPORT_SYMBOL(down_write); @@ -88,7 +83,6 @@ int __sched down_write_killable(struct rw_semaphore *sem) return -EINTR; } - rwsem_set_owner(sem); return 0; } @@ -101,10 +95,8 @@ int down_write_trylock(struct rw_semaphore *sem) { int ret = __down_write_trylock(sem); - if (ret == 1) { + if (ret == 1) rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_); - rwsem_set_owner(sem); - } return ret; } @@ -119,7 +111,6 @@ void up_read(struct rw_semaphore *sem) rwsem_release(&sem->dep_map, 1, _RET_IP_); DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED)); - rwsem_clear_reader_owned(sem); __up_read(sem); } @@ -133,7 +124,6 @@ void up_write(struct rw_semaphore *sem) rwsem_release(&sem->dep_map, 1, _RET_IP_); DEBUG_RWSEMS_WARN_ON(sem->owner != current); - rwsem_clear_owner(sem); __up_write(sem); } @@ -147,7 +137,6 @@ void downgrade_write(struct rw_semaphore *sem) lock_downgrade(&sem->dep_map, _RET_IP_); DEBUG_RWSEMS_WARN_ON(sem->owner != current); - rwsem_set_reader_owned(sem); __downgrade_write(sem); } @@ -161,7 +150,6 @@ void down_read_nested(struct rw_semaphore *sem, int subclass) rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_read_trylock, __down_read); - rwsem_set_reader_owned(sem); } EXPORT_SYMBOL(down_read_nested); @@ -172,7 +160,6 @@ void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest) rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_); LOCK_CONTENDED(sem, __down_write_trylock, __down_write); - rwsem_set_owner(sem); } EXPORT_SYMBOL(_down_write_nest_lock); @@ -193,7 +180,6 @@ void down_write_nested(struct rw_semaphore *sem, int subclass) rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_write_trylock, __down_write); - rwsem_set_owner(sem); } EXPORT_SYMBOL(down_write_nested); @@ -208,7 +194,6 @@ int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass) return -EINTR; } - rwsem_set_owner(sem); return 0; } diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h index 067e265..f568391 100644 --- a/kernel/locking/rwsem.h +++ b/kernel/locking/rwsem.h @@ -161,6 +161,8 @@ static inline void __down_read(struct rw_semaphore *sem) { if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) rwsem_down_read_failed(sem); + else + rwsem_set_reader_owned(sem); } static inline int __down_read_killable(struct rw_semaphore *sem) @@ -168,8 +170,9 @@ static inline int __down_read_killable(struct rw_semaphore *sem) if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) { if (IS_ERR(rwsem_down_read_failed_killable(sem))) return -EINTR; + } else { + rwsem_set_reader_owned(sem); } - return 0; } @@ -180,6 +183,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) while ((tmp = atomic_long_read(&sem->count)) >= 0) { if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp, tmp + RWSEM_ACTIVE_READ_BIAS)) { + rwsem_set_reader_owned(sem); return 1; } } @@ -197,6 +201,7 @@ static inline void __down_write(struct rw_semaphore *sem) &sem->count); if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) rwsem_down_write_failed(sem); + rwsem_set_owner(sem); } static inline int __down_write_killable(struct rw_semaphore *sem) @@ -208,6 +213,7 @@ static inline int __down_write_killable(struct rw_semaphore *sem) if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) if (IS_ERR(rwsem_down_write_failed_killable(sem))) return -EINTR; + rwsem_set_owner(sem); return 0; } @@ -217,7 +223,11 @@ static inline int __down_write_trylock(struct rw_semaphore *sem) tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE, RWSEM_ACTIVE_WRITE_BIAS); - return tmp == RWSEM_UNLOCKED_VALUE; + if (tmp == RWSEM_UNLOCKED_VALUE) { + rwsem_set_owner(sem); + return true; + } + return false; } /* @@ -227,6 +237,7 @@ static inline void __up_read(struct rw_semaphore *sem) { long tmp; + rwsem_clear_reader_owned(sem); tmp = atomic_long_dec_return_release(&sem->count); if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)) rwsem_wake(sem); @@ -237,6 +248,7 @@ static inline void __up_read(struct rw_semaphore *sem) */ static inline void __up_write(struct rw_semaphore *sem) { + rwsem_clear_owner(sem); if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS, &sem->count) < 0)) rwsem_wake(sem); @@ -257,6 +269,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem) * write side. As such, rely on RELEASE semantics. */ tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS, &sem->count); + rwsem_set_reader_owned(sem); if (tmp < 0) rwsem_downgrade_wake(sem); }