diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/rcupdate.c | 4 | ||||
| -rw-r--r-- | kernel/rcutiny.c | 291 | ||||
| -rw-r--r-- | kernel/rcutorture.c | 31 | ||||
| -rw-r--r-- | kernel/rcutree.c | 7 | ||||
| -rw-r--r-- | kernel/rcutree_trace.c | 8 | ||||
| -rw-r--r-- | kernel/softirq.c | 2 | ||||
| -rw-r--r-- | kernel/srcu.c | 74 |
8 files changed, 385 insertions, 33 deletions
diff --git a/kernel/Makefile b/kernel/Makefile index b8d4cd8ac0b..e9a0e6ed25c 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -82,6 +82,7 @@ obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o obj-$(CONFIG_TREE_RCU) += rcutree.o obj-$(CONFIG_TREE_PREEMPT_RCU) += rcutree.o obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o +obj-$(CONFIG_TINY_RCU) += rcutiny.o obj-$(CONFIG_RELAY) += relay.o obj-$(CONFIG_SYSCTL) += utsname_sysctl.o obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 400183346ad..7625f207f65 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -67,6 +67,8 @@ void wakeme_after_rcu(struct rcu_head *head) complete(&rcu->completion); } +#ifndef CONFIG_TINY_RCU + #ifdef CONFIG_TREE_PREEMPT_RCU /** @@ -157,6 +159,8 @@ void synchronize_rcu_bh(void) } EXPORT_SYMBOL_GPL(synchronize_rcu_bh); +#endif /* #ifndef CONFIG_TINY_RCU */ + static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self, unsigned long action, void *hcpu) { diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c new file mode 100644 index 00000000000..b33ec3aa377 --- /dev/null +++ b/kernel/rcutiny.c @@ -0,0 +1,291 @@ +/* + * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition. + * + * 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, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright IBM Corporation, 2008 + * + * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU + */ +#include <linux/moduleparam.h> +#include <linux/completion.h> +#include <linux/interrupt.h> +#include <linux/notifier.h> +#include <linux/rcupdate.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/sched.h> +#include <linux/types.h> +#include <linux/init.h> +#include <linux/time.h> +#include <linux/cpu.h> + +/* Global control variables for rcupdate callback mechanism. */ +struct rcu_ctrlblk { + struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */ + struct rcu_head **donetail; /* ->next pointer of last "done" CB. */ + struct rcu_head **curtail; /* ->next pointer of last CB. */ +}; + +/* Definition for rcupdate control block. */ +static struct rcu_ctrlblk rcu_ctrlblk = { + .donetail = &rcu_ctrlblk.rcucblist, + .curtail = &rcu_ctrlblk.rcucblist, +}; + +static struct rcu_ctrlblk rcu_bh_ctrlblk = { + .donetail = &rcu_bh_ctrlblk.rcucblist, + .curtail = &rcu_bh_ctrlblk.rcucblist, +}; + +#ifdef CONFIG_NO_HZ + +static long rcu_dynticks_nesting = 1; + +/* + * Enter dynticks-idle mode, which is an extended quiescent state + * if we have fully entered that mode (i.e., if the new value of + * dynticks_nesting is zero). + */ +void rcu_enter_nohz(void) +{ + if (--rcu_dynticks_nesting == 0) + rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ +} + +/* + * Exit dynticks-idle mode, so that we are no longer in an extended + * quiescent state. + */ +void rcu_exit_nohz(void) +{ + rcu_dynticks_nesting++; +} + +#endif /* #ifdef CONFIG_NO_HZ */ + +/* + * Helper function for rcu_qsctr_inc() and rcu_bh_qsctr_inc(). + * Also disable irqs to avoid confusion due to interrupt handlers + * invoking call_rcu(). + */ +static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) +{ + unsigned long flags; + + local_irq_save(flags); + if (rcp->rcucblist != NULL && + rcp->donetail != rcp->curtail) { + rcp->donetail = rcp->curtail; + local_irq_restore(flags); + return 1; + } + local_irq_restore(flags); + + return 0; +} + +/* + * Record an rcu quiescent state. And an rcu_bh quiescent state while we + * are at it, given that any rcu quiescent state is also an rcu_bh + * quiescent state. Use "+" instead of "||" to defeat short circuiting. + */ +void rcu_sched_qs(int cpu) +{ + if (rcu_qsctr_help(&rcu_ctrlblk) + rcu_qsctr_help(&rcu_bh_ctrlblk)) + raise_softirq(RCU_SOFTIRQ); +} + +/* + * Record an rcu_bh quiescent state. + */ +void rcu_bh_qs(int cpu) +{ + if (rcu_qsctr_help(&rcu_bh_ctrlblk)) + raise_softirq(RCU_SOFTIRQ); +} + +/* + * Check to see if the scheduling-clock interrupt came from an extended + * quiescent state, and, if so, tell RCU about it. + */ +void rcu_check_callbacks(int cpu, int user) +{ + if (user || + (idle_cpu(cpu) && + !in_softirq() && + hardirq_count() <= (1 << HARDIRQ_SHIFT))) + rcu_sched_qs(cpu); + else if (!in_softirq()) + rcu_bh_qs(cpu); +} + +/* + * Helper function for rcu_process_callbacks() that operates on the + * specified rcu_ctrlkblk structure. + */ +static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) +{ + struct rcu_head *next, *list; + unsigned long flags; + + /* If no RCU callbacks ready to invoke, just return. */ + if (&rcp->rcucblist == rcp->donetail) + return; + + /* Move the ready-to-invoke callbacks to a local list. */ + local_irq_save(flags); + list = rcp->rcucblist; + rcp->rcucblist = *rcp->donetail; + *rcp->donetail = NULL; + if (rcp->curtail == rcp->donetail) + rcp->curtail = &rcp->rcucblist; + rcp->donetail = &rcp->rcucblist; + local_irq_restore(flags); + + /* Invoke the callbacks on the local list. */ + while (list) { + next = list->next; + prefetch(next); + list->func(list); + list = next; + } +} + +/* + * Invoke any callbacks whose grace period has completed. + */ +static void rcu_process_callbacks(struct softirq_action *unused) +{ + __rcu_process_callbacks(&rcu_ctrlblk); + __rcu_process_callbacks(&rcu_bh_ctrlblk); +} + +/* + * Null function to handle CPU being onlined. Longer term, we want to + * make TINY_RCU avoid using rcupdate.c, but later... + */ +int rcu_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) +{ + return NOTIFY_OK; +} + +/* + * Wait for a grace period to elapse. But it is illegal to invoke + * synchronize_sched() from within an RCU read-side critical section. + * Therefore, any legal call to synchronize_sched() is a quiescent + * state, and so on a UP system, synchronize_sched() need do nothing. + * Ditto for synchronize_rcu_bh(). (But Lai Jiangshan points out the + * benefits of doing might_sleep() to reduce latency.) + * + * Cool, huh? (Due to Josh Triplett.) + * + * But we want to make this a static inline later. + */ +void synchronize_sched(void) +{ + cond_resched(); +} +EXPORT_SYMBOL_GPL(synchronize_sched); + +void synchronize_rcu_bh(void) +{ + synchronize_sched(); +} +EXPORT_SYMBOL_GPL(synchronize_rcu_bh); + +/* + * Helper function for call_rcu() and call_rcu_bh(). + */ +static void __call_rcu(struct rcu_head *head, + void (*func)(struct rcu_head *rcu), + struct rcu_ctrlblk *rcp) +{ + unsigned long flags; + + head->func = func; + head->next = NULL; + + local_irq_save(flags); + *rcp->curtail = head; + rcp->curtail = &head->next; + local_irq_restore(flags); +} + +/* + * Post an RCU callback to be invoked after the end of an RCU grace + * period. But since we have but one CPU, that would be after any + * quiescent state. + */ +void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) +{ + __call_rcu(head, func, &rcu_ctrlblk); +} +EXPORT_SYMBOL_GPL(call_rcu); + +/* + * Post an RCU bottom-half callback to be invoked after any subsequent + * quiescent state. + */ +void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) +{ + __call_rcu(head, func, &rcu_bh_ctrlblk); +} +EXPORT_SYMBOL_GPL(call_rcu_bh); + +void rcu_barrier(void) +{ + struct rcu_synchronize rcu; + + init_completion(&rcu.completion); + /* Will wake me after RCU finished. */ + call_rcu(&rcu.head, wakeme_after_rcu); + /* Wait for it. */ + wait_for_completion(&rcu.completion); +} +EXPORT_SYMBOL_GPL(rcu_barrier); + +void rcu_barrier_bh(void) +{ + struct rcu_synchronize rcu; + + init_completion(&rcu.completion); + /* Will wake me after RCU finished. */ + call_rcu_bh(&rcu.head, wakeme_after_rcu); + /* Wait for it. */ + wait_for_completion(&rcu.completion); +} +EXPORT_SYMBOL_GPL(rcu_barrier_bh); + +void rcu_barrier_sched(void) +{ + struct rcu_synchronize rcu; + + init_completion(&rcu.completion); + /* Will wake me after RCU finished. */ + call_rcu_sched(&rcu.head, wakeme_after_rcu); + /* Wait for it. */ + wait_for_completion(&rcu.completion); +} +EXPORT_SYMBOL_GPL(rcu_barrier_sched); + +void __rcu_init(void) +{ + open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); +} diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 697c0a0229d..3dd0ca23e19 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -547,6 +547,25 @@ static struct rcu_torture_ops srcu_ops = { .name = "srcu" }; +static void srcu_torture_synchronize_expedited(void) +{ + synchronize_srcu_expedited(&srcu_ctl); +} + +static struct rcu_torture_ops srcu_expedited_ops = { + .init = srcu_torture_init, + .cleanup = srcu_torture_cleanup, + .readlock = srcu_torture_read_lock, + .read_delay = srcu_read_delay, + .readunlock = srcu_torture_read_unlock, + .completed = srcu_torture_completed, + .deferred_free = rcu_sync_torture_deferred_free, + .sync = srcu_torture_synchronize_expedited, + .cb_barrier = NULL, + .stats = srcu_torture_stats, + .name = "srcu_expedited" +}; + /* * Definitions for sched torture testing. */ @@ -592,7 +611,7 @@ static struct rcu_torture_ops sched_ops = { .name = "sched" }; -static struct rcu_torture_ops sched_ops_sync = { +static struct rcu_torture_ops sched_sync_ops = { .init = rcu_sync_torture_init, .cleanup = NULL, .readlock = sched_torture_read_lock, @@ -1098,8 +1117,8 @@ rcu_torture_init(void) int firsterr = 0; static struct rcu_torture_ops *torture_ops[] = { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops, - &sched_expedited_ops, - &srcu_ops, &sched_ops, &sched_ops_sync, }; + &srcu_ops, &srcu_expedited_ops, + &sched_ops, &sched_sync_ops, &sched_expedited_ops, }; mutex_lock(&fullstop_mutex); @@ -1110,8 +1129,12 @@ rcu_torture_init(void) break; } if (i == ARRAY_SIZE(torture_ops)) { - printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n", + printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n", torture_type); + printk(KERN_ALERT "rcu-torture types:"); + for (i = 0; i < ARRAY_SIZE(torture_ops); i++) + printk(KERN_ALERT " %s", torture_ops[i]->name); + printk(KERN_ALERT "\n"); mutex_unlock(&fullstop_mutex); return -EINVAL; } diff --git a/kernel/rcutree.c b/kernel/rcutree.c index f3077c0ab18..69f4efec344 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -51,6 +51,8 @@ /* Data structures. */ +static struct lock_class_key rcu_root_class; + #define RCU_STATE_INITIALIZER(name) { \ .level = { &name.node[0] }, \ .levelcnt = { \ @@ -1685,8 +1687,7 @@ static void __init rcu_init_one(struct rcu_state *rsp) cpustride *= rsp->levelspread[i]; rnp = rsp->level[i]; for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { - if (rnp != rcu_get_root(rsp)) - spin_lock_init(&rnp->lock); + spin_lock_init(&rnp->lock); rnp->gpnum = 0; rnp->qsmask = 0; rnp->qsmaskinit = 0; @@ -1709,7 +1710,7 @@ static void __init rcu_init_one(struct rcu_state *rsp) INIT_LIST_HEAD(&rnp->blocked_tasks[1]); } } - spin_lock_init(&rcu_get_root(rsp)->lock); + lockdep_set_class(&rcu_get_root(rsp)->lock, &rcu_root_class); } /* diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 4b31c779e62..1984cdc51e9 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -155,12 +155,14 @@ static const struct file_operations rcudata_csv_fops = { static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) { + long gpnum; int level = 0; struct rcu_node *rnp; + gpnum = rsp->gpnum; seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x " "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld\n", - rsp->completed, rsp->gpnum, rsp->signaled, + rsp->completed, gpnum, rsp->signaled, (long)(rsp->jiffies_force_qs - jiffies), (int)(jiffies & 0xffff), rsp->n_force_qs, rsp->n_force_qs_ngp, @@ -171,8 +173,10 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) seq_puts(m, "\n"); level = rnp->level; } - seq_printf(m, "%lx/%lx %d:%d ^%d ", + seq_printf(m, "%lx/%lx %c>%c %d:%d ^%d ", rnp->qsmask, rnp->qsmaskinit, + "T."[list_empty(&rnp->blocked_tasks[gpnum & 1])], + "T."[list_empty(&rnp->blocked_tasks[!(gpnum & 1)])], rnp->grplo, rnp->grphi, rnp->grpnum); } seq_puts(m, "\n"); diff --git a/kernel/softirq.c b/kernel/softirq.c index f8749e5216e..21939d9e830 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -302,9 +302,9 @@ void irq_exit(void) if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); + rcu_irq_exit(); #ifdef CONFIG_NO_HZ /* Make sure that timer wheel updates are propagated */ - rcu_irq_exit(); if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) tick_nohz_stop_sched_tick(0); #endif diff --git a/kernel/srcu.c b/kernel/srcu.c index b0aeeaf22ce..818d7d9aa03 100644 --- a/kernel/srcu.c +++ b/kernel/srcu.c @@ -49,6 +49,7 @@ int init_srcu_struct(struct srcu_struct *sp) sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array); return (sp->per_cpu_ref ? 0 : -ENOMEM); } +EXPORT_SYMBOL_GPL(init_srcu_struct); /* * srcu_readers_active_idx -- returns approximate number of readers @@ -97,6 +98,7 @@ void cleanup_srcu_struct(struct srcu_struct *sp) free_percpu(sp->per_cpu_ref); sp->per_cpu_ref = NULL; } +EXPORT_SYMBOL_GPL(cleanup_srcu_struct); /** * srcu_read_lock - register a new reader for an SRCU-protected structure. @@ -118,6 +120,7 @@ int srcu_read_lock(struct srcu_struct *sp) preempt_enable(); return idx; } +EXPORT_SYMBOL_GPL(srcu_read_lock); /** * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. @@ -136,22 +139,12 @@ void srcu_read_unlock(struct srcu_struct *sp, int idx) per_cpu_ptr(sp->per_cpu_ref, smp_processor_id())->c[idx]--; preempt_enable(); } +EXPORT_SYMBOL_GPL(srcu_read_unlock); -/** - * synchronize_srcu - wait for prior SRCU read-side critical-section completion - * @sp: srcu_struct with which to synchronize. - * - * Flip the completed counter, and wait for the old count to drain to zero. - * As with classic RCU, the updater must use some separate means of - * synchronizing concurrent updates. Can block; must be called from - * process context. - * - * Note that it is illegal to call synchornize_srcu() from the corresponding - * SRCU read-side critical section; doing so will result in deadlock. - * However, it is perfectly legal to call synchronize_srcu() on one - * srcu_struct from some other srcu_struct's read-side critical section. +/* + * Helper function for synchronize_srcu() and synchronize_srcu_expedited(). */ -void synchronize_srcu(struct srcu_struct *sp) +void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void)) { int idx; @@ -173,7 +166,7 @@ void synchronize_srcu(struct srcu_struct *sp) return; } - synchronize_sched(); /* Force memory barrier on all CPUs. */ + sync_func(); /* Force memory barrier on all CPUs. */ /* * The preceding synchronize_sched() ensures that any CPU that @@ -190,7 +183,7 @@ void synchronize_srcu(struct srcu_struct *sp) idx = sp->completed & 0x1; sp->completed++; - synchronize_sched(); /* Force memory barrier on all CPUs. */ + sync_func(); /* Force memory barrier on all CPUs. */ /* * At this point, because of the preceding synchronize_sched(), @@ -203,7 +196,7 @@ void synchronize_srcu(struct srcu_struct *sp) while (srcu_readers_active_idx(sp, idx)) schedule_timeout_interruptible(1); - synchronize_sched(); /* Force memory barrier on all CPUs. */ + sync_func(); /* Force memory barrier on all CPUs. */ /* * The preceding synchronize_sched() forces all srcu_read_unlock() @@ -237,6 +230,47 @@ void synchronize_srcu(struct srcu_struct *sp) } /** + * synchronize_srcu - wait for prior SRCU read-side critical-section completion + * @sp: srcu_struct with which to synchronize. + * + * Flip the completed counter, and wait for the old count to drain to zero. + * As with classic RCU, the updater must use some separate means of + * synchronizing concurrent updates. Can block; must be called from + * process context. + * + * Note that it is illegal to call synchronize_srcu() from the corresponding + * SRCU read-side critical section; doing so will result in deadlock. + * However, it is perfectly legal to call synchronize_srcu() on one + * srcu_struct from some other srcu_struct's read-side critical section. + */ +void synchronize_srcu(struct srcu_struct *sp) +{ + __synchronize_srcu(sp, synchronize_sched); +} +EXPORT_SYMBOL_GPL(synchronize_srcu); + +/** + * synchronize_srcu_expedited - like synchronize_srcu, but less patient + * @sp: srcu_struct with which to synchronize. + * + * Flip the completed counter, and wait for the old count to drain to zero. + * As with classic RCU, the updater must use some separate means of + * synchronizing concurrent updates. Can block; must be called from + * process context. + * + * Note that it is illegal to call synchronize_srcu_expedited() + * from the corresponding SRCU read-side critical section; doing so + * will result in deadlock. However, it is perfectly legal to call + * synchronize_srcu_expedited() on one srcu_struct from some other + * srcu_struct's read-side critical section. + */ +void synchronize_srcu_expedited(struct srcu_struct *sp) +{ + __synchronize_srcu(sp, synchronize_sched_expedited); +} +EXPORT_SYMBOL_GPL(synchronize_srcu_expedited); + +/** * srcu_batches_completed - return batches completed. * @sp: srcu_struct on which to report batch completion. * @@ -248,10 +282,4 @@ long srcu_batches_completed(struct srcu_struct *sp) { return sp->completed; } - -EXPORT_SYMBOL_GPL(init_srcu_struct); -EXPORT_SYMBOL_GPL(cleanup_srcu_struct); -EXPORT_SYMBOL_GPL(srcu_read_lock); -EXPORT_SYMBOL_GPL(srcu_read_unlock); -EXPORT_SYMBOL_GPL(synchronize_srcu); EXPORT_SYMBOL_GPL(srcu_batches_completed); |