From d8be81735aa89413b333de488251f0e64e2be591 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 25 Mar 2017 09:59:38 -0700 Subject: srcu: Create a tiny SRCU In response to automated complaints about modifications to SRCU increasing its size, this commit creates a tiny SRCU that is used in SMP=n && PREEMPT=n builds. Signed-off-by: Paul E. McKenney --- include/linux/srcutiny.h | 81 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 include/linux/srcutiny.h (limited to 'include/linux/srcutiny.h') diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h new file mode 100644 index 000000000000..4f284e4f4d8c --- /dev/null +++ b/include/linux/srcutiny.h @@ -0,0 +1,81 @@ +/* + * Sleepable Read-Copy Update mechanism for mutual exclusion, + * tiny variant. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. + * + * Copyright (C) IBM Corporation, 2017 + * + * Author: Paul McKenney + */ + +#ifndef _LINUX_SRCU_TINY_H +#define _LINUX_SRCU_TINY_H + +#include + +struct srcu_struct { + int srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */ + struct swait_queue_head srcu_wq; + /* Last srcu_read_unlock() wakes GP. */ + unsigned long srcu_gp_seq; /* GP seq # for callback tagging. */ + struct rcu_segcblist srcu_cblist; + /* Pending SRCU callbacks. */ + int srcu_idx; /* Current reader array element. */ + bool srcu_gp_running; /* GP workqueue running? */ + bool srcu_gp_waiting; /* GP waiting for readers? */ + struct work_struct srcu_work; /* For driving grace periods. */ +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +}; + +void srcu_drive_gp(struct work_struct *wp); + +#define __SRCU_STRUCT_INIT(name) \ +{ \ + .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \ + .srcu_cblist = RCU_SEGCBLIST_INITIALIZER(name.srcu_cblist), \ + .srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp), \ + __SRCU_DEP_MAP_INIT(name) \ +} + +/* + * This odd _STATIC_ arrangement is needed for API compatibility with + * Tree SRCU, which needs some per-CPU data. + */ +#define DEFINE_SRCU(name) \ + struct srcu_struct name = __SRCU_STRUCT_INIT(name) +#define DEFINE_STATIC_SRCU(name) \ + static struct srcu_struct name = __SRCU_STRUCT_INIT(name) + +void synchronize_srcu(struct srcu_struct *sp); + +static inline void synchronize_srcu_expedited(struct srcu_struct *sp) +{ + synchronize_srcu(sp); +} + +static inline void srcu_barrier(struct srcu_struct *sp) +{ + synchronize_srcu(sp); +} + +static inline unsigned long srcu_batches_completed(struct srcu_struct *sp) +{ + return 0; +} + +#endif -- cgit v1.2.3 From 7f6733c3c648ddd6cf459c1b80ad388a95452955 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 18 Apr 2017 17:17:35 -0700 Subject: srcu: Make rcutorture writer stalls print SRCU GP state In the past, SRCU was simple enough that there was little point in making the rcutorture writer stall messages print the SRCU grace-period number state. With the advent of Tree SRCU, this has changed. This commit therefore makes Classic, Tiny, and Tree SRCU report this state to rcutorture as needed. Signed-off-by: Paul E. McKenney Tested-by: Mike Galbraith --- include/linux/srcuclassic.h | 14 ++++++++++++++ include/linux/srcutiny.h | 12 ++++++++++++ include/linux/srcutree.h | 4 ++++ kernel/rcu/rcutorture.c | 8 +++++--- kernel/rcu/srcutree.c | 13 +++++++++++++ kernel/rcu/tree.c | 12 ++++-------- 6 files changed, 52 insertions(+), 11 deletions(-) (limited to 'include/linux/srcutiny.h') diff --git a/include/linux/srcuclassic.h b/include/linux/srcuclassic.h index 41cf99930f34..5753f7322262 100644 --- a/include/linux/srcuclassic.h +++ b/include/linux/srcuclassic.h @@ -98,4 +98,18 @@ void synchronize_srcu_expedited(struct srcu_struct *sp); void srcu_barrier(struct srcu_struct *sp); unsigned long srcu_batches_completed(struct srcu_struct *sp); +static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, + struct srcu_struct *sp, int *flags, + unsigned long *gpnum, + unsigned long *completed) +{ + if (test_type != SRCU_FLAVOR) + return; + *flags = 0; + *completed = sp->completed; + *gpnum = *completed; + if (sp->batch_queue.head || sp->batch_check0.head || sp->batch_check0.head) + (*gpnum)++; +} + #endif diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h index 4f284e4f4d8c..42311ee0334f 100644 --- a/include/linux/srcutiny.h +++ b/include/linux/srcutiny.h @@ -78,4 +78,16 @@ static inline unsigned long srcu_batches_completed(struct srcu_struct *sp) return 0; } +static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, + struct srcu_struct *sp, int *flags, + unsigned long *gpnum, + unsigned long *completed) +{ + if (test_type != SRCU_FLAVOR) + return; + *flags = 0; + *completed = sp->srcu_gp_seq; + *gpnum = *completed; +} + #endif diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 94515ff226fb..3865717df124 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -140,4 +140,8 @@ void synchronize_srcu_expedited(struct srcu_struct *sp); void srcu_barrier(struct srcu_struct *sp); unsigned long srcu_batches_completed(struct srcu_struct *sp); +void srcutorture_get_gp_data(enum rcutorture_type test_type, + struct srcu_struct *sp, int *flags, + unsigned long *gpnum, unsigned long *completed); + #endif diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index e9d4527cdd43..ae6e574d4cf5 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1360,12 +1360,14 @@ rcu_torture_stats_print(void) cur_ops->stats(); if (rtcv_snap == rcu_torture_current_version && rcu_torture_current != NULL) { - int __maybe_unused flags; - unsigned long __maybe_unused gpnum; - unsigned long __maybe_unused completed; + int __maybe_unused flags = 0; + unsigned long __maybe_unused gpnum = 0; + unsigned long __maybe_unused completed = 0; rcutorture_get_gp_data(cur_ops->ttype, &flags, &gpnum, &completed); + srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, + &flags, &gpnum, &completed); wtp = READ_ONCE(writer_task); pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n", rcu_torture_writer_state_getname(), diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 1c2c1004b3b1..72b6cce5f591 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1011,3 +1011,16 @@ void process_srcu(struct work_struct *work) srcu_reschedule(sp, atomic_read(&sp->srcu_exp_cnt) ? 0 : SRCU_INTERVAL); } EXPORT_SYMBOL_GPL(process_srcu); + +void srcutorture_get_gp_data(enum rcutorture_type test_type, + struct srcu_struct *sp, int *flags, + unsigned long *gpnum, + unsigned long *completed) +{ + if (test_type != SRCU_FLAVOR) + return; + *flags = 0; + *completed = rcu_seq_ctr(sp->srcu_gp_seq); + *gpnum = rcu_seq_ctr(sp->srcu_gp_seq_needed); +} +EXPORT_SYMBOL_GPL(srcutorture_get_gp_data); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 23aa02587d0f..91fff49d5869 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -704,15 +704,11 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, default: break; } - if (rsp != NULL) { - *flags = READ_ONCE(rsp->gp_flags); - *gpnum = READ_ONCE(rsp->gpnum); - *completed = READ_ONCE(rsp->completed); + if (rsp == NULL) return; - } - *flags = 0; - *gpnum = 0; - *completed = 0; + *flags = READ_ONCE(rsp->gp_flags); + *gpnum = READ_ONCE(rsp->gpnum); + *completed = READ_ONCE(rsp->completed); } EXPORT_SYMBOL_GPL(rcutorture_get_gp_data); -- cgit v1.2.3