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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 CCDDFC43331 for ; Fri, 6 Sep 2019 14:36:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A32A7206A1 for ; Fri, 6 Sep 2019 14:36:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="rs1LOkTg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392905AbfIFOg1 (ORCPT ); Fri, 6 Sep 2019 10:36:27 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:36498 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731943AbfIFOg0 (ORCPT ); Fri, 6 Sep 2019 10:36:26 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x86ESr5d027745; Fri, 6 Sep 2019 14:33:32 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2019-08-05; bh=pqlD6DSkPCSnh47TAR8M8rb2PO6xpJG7A2fplM94Pms=; b=rs1LOkTgh6BV5Reu1OJOhNg2rUA/k2kQ8d32UpWp+l4CRdQTUX7mNJ9iO75ybf8lrZCD lh0ie2ISNr4CyOGUDm2F0p5+bjM/vJJEt/c/zKtKaGceBsKazWr6ZPzYvciywWHlrkyf cMWjjuK90dKGaqmoOW0GvkVz6aaZQ1tO0A5jCDaEmsVJ9gchv4Wlmo5T/E4VgvER4IqF XskfpSbYGJn7z4CHe/uKzyENyzugB4UUbTxJSOKtvt6f5aCgNTONynBevyIxXnp72UT/ Hysf2h/RHVBK1J/YVWA6eK1zHq+IQVMMCCOTMCcigxf8ZvpslthGvGWDznMIJPYm9hOt Zg== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 2uus4kg2xm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 06 Sep 2019 14:33:31 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x86EXR7X079729; Fri, 6 Sep 2019 14:33:31 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 2uud7pk6h3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 06 Sep 2019 14:33:31 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x86EWtgM007506; Fri, 6 Sep 2019 14:32:55 GMT Received: from neelam.us.oracle.com (/10.152.128.16) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 06 Sep 2019 07:32:54 -0700 From: Alex Kogan To: linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, longman@redhat.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com, jglauber@marvell.com Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, alex.kogan@oracle.com, dave.dice@oracle.com, rahul.x.yadav@oracle.com Subject: [PATCH v4 2/5] locking/qspinlock: Refactor the qspinlock slow path Date: Fri, 6 Sep 2019 10:25:38 -0400 Message-Id: <20190906142541.34061-3-alex.kogan@oracle.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190906142541.34061-1-alex.kogan@oracle.com> References: <20190906142541.34061-1-alex.kogan@oracle.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9372 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1909060153 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9372 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1909060153 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Move some of the code manipulating the spin lock into separate functions. This would allow easier integration of alternative ways to manipulate that lock. Signed-off-by: Alex Kogan Reviewed-by: Steve Sistare --- kernel/locking/qspinlock.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index c3dfcb689400..070015156a10 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -288,6 +288,34 @@ static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock, #define queued_spin_lock_slowpath native_queued_spin_lock_slowpath #endif +/* + * __try_clear_tail - try to clear tail by setting the lock value to + * _Q_LOCKED_VAL. + * @lock: Pointer to the queued spinlock structure + * @val: Current value of the lock + * @node: Pointer to the MCS node of the lock holder + */ +static __always_inline bool __try_clear_tail(struct qspinlock *lock, + u32 val, + struct mcs_spinlock *node) +{ + return atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL); +} + +/* + * __mcs_pass_lock - pass the MCS lock to the next waiter + * @node: Pointer to the MCS node of the lock holder + * @next: Pointer to the MCS node of the first waiter in the MCS queue + */ +static __always_inline void __mcs_pass_lock(struct mcs_spinlock *node, + struct mcs_spinlock *next) +{ + arch_mcs_pass_lock(&next->locked, 1); +} + +#define try_clear_tail __try_clear_tail +#define mcs_pass_lock __mcs_pass_lock + #endif /* _GEN_PV_LOCK_SLOWPATH */ /** @@ -532,7 +560,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) * PENDING will make the uncontended transition fail. */ if ((val & _Q_TAIL_MASK) == tail) { - if (atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL)) + if (try_clear_tail(lock, val, node)) goto release; /* No contention */ } @@ -549,7 +577,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) if (!next) next = smp_cond_load_relaxed(&node->next, (VAL)); - arch_mcs_pass_lock(&next->locked, 1); + mcs_pass_lock(node, next); pv_kick_node(lock, next); release: @@ -574,6 +602,12 @@ EXPORT_SYMBOL(queued_spin_lock_slowpath); #undef pv_kick_node #undef pv_wait_head_or_lock +#undef try_clear_tail +#define try_clear_tail __try_clear_tail + +#undef mcs_pass_lock +#define mcs_pass_lock __mcs_pass_lock + #undef queued_spin_lock_slowpath #define queued_spin_lock_slowpath __pv_queued_spin_lock_slowpath -- 2.11.0 (Apple Git-81)