From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932530AbdDQXsU (ORCPT ); Mon, 17 Apr 2017 19:48:20 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47711 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755717AbdDQXpl (ORCPT ); Mon, 17 Apr 2017 19:45:41 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH v2 tip/core/rcu 22/39] srcu: Add grace-period sequence numbers Date: Mon, 17 Apr 2017 16:45:09 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170417234452.GB19013@linux.vnet.ibm.com> References: <20170417234452.GB19013@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17041723-0052-0000-0000-000001DACAF1 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006935; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00848869; UDB=6.00419099; IPR=6.00627510; BA=6.00005292; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015073; XFM=3.00000013; UTC=2017-04-17 23:45:37 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17041723-0053-0000-0000-00005005871F Message-Id: <1492472726-3841-22-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-17_20:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1704170205 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit adds grace-period sequence numbers, which will be used to handle mid-boot grace periods and per-CPU callback lists. Signed-off-by: Paul E. McKenney --- include/linux/srcu.h | 1 + kernel/rcu/srcu.c | 27 +++++++++++++++++++++++---- 2 files changed, 24 insertions(+), 4 deletions(-) diff --git a/include/linux/srcu.h b/include/linux/srcu.h index f149a685896c..047ac8c28a4e 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -46,6 +46,7 @@ struct rcu_batch { struct srcu_struct { unsigned long completed; + unsigned long srcu_gp_seq; struct srcu_array __percpu *per_cpu_ref; spinlock_t queue_lock; /* protect ->batch_queue, ->running */ int srcu_state; diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c index 84da09c02971..ed7c3d082b9f 100644 --- a/kernel/rcu/srcu.c +++ b/kernel/rcu/srcu.c @@ -110,6 +110,7 @@ static inline void rcu_batch_move(struct rcu_batch *to, struct rcu_batch *from) static int init_srcu_struct_fields(struct srcu_struct *sp) { sp->completed = 0; + sp->srcu_gp_seq = 0; spin_lock_init(&sp->queue_lock); sp->srcu_state = SRCU_STATE_IDLE; rcu_batch_init(&sp->batch_queue); @@ -313,6 +314,15 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); #define SYNCHRONIZE_SRCU_EXP_TRYCOUNT 12 /* + * Start an SRCU grace period. + */ +static void srcu_gp_start(struct srcu_struct *sp) +{ + WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1); + rcu_seq_start(&sp->srcu_gp_seq); +} + +/* * @@@ Wait until all pre-existing readers complete. Such readers * will have used the index specified by "idx". * the caller should ensures the ->completed is not changed while checking @@ -349,6 +359,15 @@ static void srcu_flip(struct srcu_struct *sp) } /* + * End an SRCU grace period. + */ +static void srcu_gp_end(struct srcu_struct *sp) +{ + rcu_seq_end(&sp->srcu_gp_seq); + WRITE_ONCE(sp->srcu_state, SRCU_STATE_DONE); +} + +/* * Enqueue an SRCU callback on the specified srcu_struct structure, * initiating grace-period processing if it is not already running. * @@ -386,7 +405,7 @@ void call_srcu(struct srcu_struct *sp, struct rcu_head *head, smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */ rcu_batch_queue(&sp->batch_queue, head); if (READ_ONCE(sp->srcu_state) == SRCU_STATE_IDLE) { - WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1); + srcu_gp_start(sp); queue_delayed_work(system_power_efficient_wq, &sp->work, 0); } spin_unlock_irqrestore(&sp->queue_lock, flags); @@ -420,7 +439,7 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount) smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */ if (READ_ONCE(sp->srcu_state) == SRCU_STATE_IDLE) { /* steal the processing owner */ - WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1); + srcu_gp_start(sp); rcu_batch_queue(&sp->batch_check0, head); spin_unlock_irq(&sp->queue_lock); /* give the processing owner to work_struct */ @@ -555,7 +574,7 @@ static void srcu_advance_batches(struct srcu_struct *sp, int trycount) */ if (sp->srcu_state == SRCU_STATE_DONE) - WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1); + srcu_gp_start(sp); if (sp->srcu_state == SRCU_STATE_SCAN1) { idx = 1 ^ (sp->completed & 1); @@ -602,7 +621,7 @@ static void srcu_advance_batches(struct srcu_struct *sp, int trycount) */ rcu_batch_move(&sp->batch_done, &sp->batch_check1); - WRITE_ONCE(sp->srcu_state, SRCU_STATE_DONE); + srcu_gp_end(sp); } } -- 2.5.2