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, 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 07D7FC64E7B for ; Tue, 17 Nov 2020 23:21:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93711222E9 for ; Tue, 17 Nov 2020 23:21:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="mPfDnJxX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729576AbgKQXVO (ORCPT ); Tue, 17 Nov 2020 18:21:14 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:44918 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729548AbgKQXVN (ORCPT ); Tue, 17 Nov 2020 18:21:13 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0AHNDc65099794; Tue, 17 Nov 2020 23:13:38 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-2020-01-29; bh=we47x/zXOJPVtNw5uym1kfGuctWw0Fy3iZ7QHb+/J1c=; b=mPfDnJxXgDZo+hX5lQzxOsle4wCCh/ahgx3oUCzNaRUYlTkPNxK6wr1I6Ffq+2R67xNY wD60/Ot4aoqf3QeVZAAPVlMzqdRMYYOkzXvI39m9520WFfKWP8xdFia2NUYMZ3VOBAUC fOCtXGeOAegJbzIWImEz/DwLZ+ulrTm9bwPE0KxnV8xREBp6fULcqzDoi6tgrOzfZ6E1 Nos57Ct+8HK+CO26Xm7YXoQFwUCsi4xHcXJiVU2wgaRHZ8SuSGUktgAA8rORLsxvMkNZ 7YG0JLEurL9iw7FqCnReSErVPoETyugcVhIvCXLZOzBfgnl1jI5smsEb0SmN0BA8Nt71 8g== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 34t7vn59rs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 17 Nov 2020 23:13:38 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0AHN5bNo161431; Tue, 17 Nov 2020 23:13:34 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 34uspu1a99-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 17 Nov 2020 23:13:34 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 0AHNDXQr028988; Tue, 17 Nov 2020 23:13:33 GMT Received: from neelam.us.oracle.com (/10.152.128.16) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 17 Nov 2020 15:13:32 -0800 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 Subject: [PATCH v12 2/5] locking/qspinlock: Refactor the qspinlock slow path Date: Tue, 17 Nov 2020 18:13:20 -0500 Message-Id: <20201117231323.797104-3-alex.kogan@oracle.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201117231323.797104-1-alex.kogan@oracle.com> References: <20201117231323.797104-1-alex.kogan@oracle.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9808 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 mlxscore=0 bulkscore=0 suspectscore=0 adultscore=0 spamscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011170172 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9808 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 suspectscore=0 malwarescore=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 spamscore=0 adultscore=0 mlxscore=0 priorityscore=1501 phishscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011170173 Precedence: bulk List-ID: X-Mailing-List: linux-arch@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 Reviewed-by: Waiman Long --- 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 435d696..e351870 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -289,6 +289,34 @@ 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_lock_handoff - 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_lock_handoff(struct mcs_spinlock *node, + struct mcs_spinlock *next) +{ + arch_mcs_lock_handoff(&next->locked, 1); +} + +#define try_clear_tail __try_clear_tail +#define mcs_lock_handoff __mcs_lock_handoff + #endif /* _GEN_PV_LOCK_SLOWPATH */ /** @@ -533,7 +561,7 @@ 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 */ } @@ -550,7 +578,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) if (!next) next = smp_cond_load_relaxed(&node->next, (VAL)); - arch_mcs_lock_handoff(&next->locked, 1); + mcs_lock_handoff(node, next); pv_kick_node(lock, next); release: @@ -575,6 +603,12 @@ 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_lock_handoff +#define mcs_lock_handoff __mcs_lock_handoff + #undef queued_spin_lock_slowpath #define queued_spin_lock_slowpath __pv_queued_spin_lock_slowpath -- 2.7.4