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Mon, 25 Nov 2019 21:15:23 +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 xAPL8x80194601; Mon, 25 Nov 2019 21:15:23 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 2wfe9htu85-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 25 Nov 2019 21:15:23 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id xAPLFEBd027489; Mon, 25 Nov 2019 21:15:14 GMT Received: from neelam.us.oracle.com (/10.152.128.16) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 25 Nov 2019 13:15:14 -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 Subject: [PATCH v7 2/5] locking/qspinlock: Refactor the qspinlock slow path Date: Mon, 25 Nov 2019 16:07:06 -0500 Message-Id: <20191125210709.10293-3-alex.kogan@oracle.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20191125210709.10293-1-alex.kogan@oracle.com> References: <20191125210709.10293-1-alex.kogan@oracle.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9452 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=8.0.1-1911140001 definitions=main-1911250171 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9452 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=8.0.1-1911140001 definitions=main-1911250171 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191125_131616_965568_9B7A7F59 X-CRM114-Status: GOOD ( 17.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alex.kogan@oracle.com, dave.dice@oracle.com, rahul.x.yadav@oracle.com, steven.sistare@oracle.com, daniel.m.jordan@oracle.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.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 804c0fbd6328..c06d1e8075d9 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 -- 2.21.0 (Apple Git-122.2) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel