Signed-off-by: Dipankar Sarma --- include/linux/rcuclassic.h | 149 +++++++++++ include/linux/rcupdate.h | 153 +++--------- kernel/Makefile | 2 kernel/rcuclassic.c | 558 ++++++++++++++++++++++++++++++++++++++++++++ kernel/rcupdate.c | 562 ++------------------------------------------- 5 files changed, 783 insertions(+), 641 deletions(-) diff -puN /dev/null include/linux/rcuclassic.h --- /dev/null 2006-09-20 22:20:57.873117750 +0530 +++ linux-2.6.18-rc6-mm1-rcu-dipankar/include/linux/rcuclassic.h 2006-09-23 03:27:38.000000000 +0530 @@ -0,0 +1,149 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (classic version) + * + * 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 (C) IBM Corporation, 2001 + * + * Author: Dipankar Sarma + * + * Based on the original work by Paul McKenney + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * Papers: + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf + * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) + * + * For detailed explanation of Read-Copy Update mechanism see - + * http://lse.sourceforge.net/locking/rcupdate.html + * + */ + +#ifndef __LINUX_RCUCLASSIC_H +#define __LINUX_RCUCLASSIC_H + +#ifdef __KERNEL__ + +#include +#include +#include +#include +#include +#include + + +/* Global control variables for rcupdate callback mechanism. */ +struct rcu_ctrlblk { + long cur; /* Current batch number. */ + long completed; /* Number of the last completed batch */ + int next_pending; /* Is the next batch already waiting? */ + + spinlock_t lock ____cacheline_internodealigned_in_smp; + cpumask_t cpumask; /* CPUs that need to switch in order */ + /* for current batch to proceed. */ +} ____cacheline_internodealigned_in_smp; + +/* Is batch a before batch b ? */ +static inline int rcu_batch_before(long a, long b) +{ + return (a - b) < 0; +} + +/* Is batch a after batch b ? */ +static inline int rcu_batch_after(long a, long b) +{ + return (a - b) > 0; +} + +/* + * Per-CPU data for Read-Copy UPdate. + * nxtlist - new callbacks are added here + * curlist - current batch for which quiescent cycle started if any + */ +struct rcu_data { + /* 1) quiescent state handling : */ + long quiescbatch; /* Batch # for grace period */ + int passed_quiesc; /* User-mode/idle loop etc. */ + int qs_pending; /* core waits for quiesc state */ + + /* 2) batch handling */ + long batch; /* Batch # for current RCU batch */ + struct rcu_head *nxtlist; + struct rcu_head **nxttail; + long qlen; /* # of queued callbacks */ + struct rcu_head *curlist; + struct rcu_head **curtail; + struct rcu_head *donelist; + struct rcu_head **donetail; + long blimit; /* Upper limit on a processed batch */ + int cpu; +#ifdef CONFIG_SMP + long last_rs_qlen; /* qlen during the last resched */ +#endif +}; + +DECLARE_PER_CPU(struct rcu_data, rcu_data); +DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); + +/* + * Increment the quiescent state counter. + * The counter is a bit degenerated: We do not need to know + * how many quiescent states passed, just if there was at least + * one since the start of the grace period. Thus just a flag. + */ +static inline void rcu_qsctr_inc(int cpu) +{ + struct rcu_data *rdp = &per_cpu(rcu_data, cpu); + rdp->passed_quiesc = 1; +} +static inline void rcu_bh_qsctr_inc(int cpu) +{ + struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); + rdp->passed_quiesc = 1; +} + +extern int rcu_pending(int cpu); +extern int rcu_needs_cpu(int cpu); + +#define __rcu_read_lock() \ + do { \ + preempt_disable(); \ + __acquire(RCU); \ + } while(0) +#define __rcu_read_unlock() \ + do { \ + __release(RCU); \ + preempt_enable(); \ + } while(0) + +#define __rcu_read_lock_bh() \ + do { \ + local_bh_disable(); \ + __acquire(RCU_BH); \ + } while(0) +#define __rcu_read_unlock_bh() \ + do { \ + __release(RCU_BH); \ + local_bh_enable(); \ + } while(0) + +#define __synchronize_sched() synchronize_rcu() + +extern void __rcu_init(void); +extern void rcu_check_callbacks(int cpu, int user); +extern void rcu_restart_cpu(int cpu); +extern long rcu_batches_completed(void); + +#endif /* __KERNEL__ */ +#endif /* __LINUX_RCUCLASSIC_H */ diff -puN include/linux/rcupdate.h~rcu-split-classic include/linux/rcupdate.h --- linux-2.6.18-rc6-mm1-rcu/include/linux/rcupdate.h~rcu-split-classic 2006-09-23 03:27:38.000000000 +0530 +++ linux-2.6.18-rc6-mm1-rcu-dipankar/include/linux/rcupdate.h 2006-09-23 03:27:38.000000000 +0530 @@ -41,6 +41,7 @@ #include #include #include +#include /** * struct rcu_head - callback structure for use with RCU @@ -59,81 +60,6 @@ struct rcu_head { } while (0) - -/* Global control variables for rcupdate callback mechanism. */ -struct rcu_ctrlblk { - long cur; /* Current batch number. */ - long completed; /* Number of the last completed batch */ - int next_pending; /* Is the next batch already waiting? */ - - spinlock_t lock ____cacheline_internodealigned_in_smp; - cpumask_t cpumask; /* CPUs that need to switch in order */ - /* for current batch to proceed. */ -} ____cacheline_internodealigned_in_smp; - -/* Is batch a before batch b ? */ -static inline int rcu_batch_before(long a, long b) -{ - return (a - b) < 0; -} - -/* Is batch a after batch b ? */ -static inline int rcu_batch_after(long a, long b) -{ - return (a - b) > 0; -} - -/* - * Per-CPU data for Read-Copy UPdate. - * nxtlist - new callbacks are added here - * curlist - current batch for which quiescent cycle started if any - */ -struct rcu_data { - /* 1) quiescent state handling : */ - long quiescbatch; /* Batch # for grace period */ - int passed_quiesc; /* User-mode/idle loop etc. */ - int qs_pending; /* core waits for quiesc state */ - - /* 2) batch handling */ - long batch; /* Batch # for current RCU batch */ - struct rcu_head *nxtlist; - struct rcu_head **nxttail; - long qlen; /* # of queued callbacks */ - struct rcu_head *curlist; - struct rcu_head **curtail; - struct rcu_head *donelist; - struct rcu_head **donetail; - long blimit; /* Upper limit on a processed batch */ - int cpu; - struct rcu_head barrier; -#ifdef CONFIG_SMP - long last_rs_qlen; /* qlen during the last resched */ -#endif -}; - -DECLARE_PER_CPU(struct rcu_data, rcu_data); -DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); - -/* - * Increment the quiescent state counter. - * The counter is a bit degenerated: We do not need to know - * how many quiescent states passed, just if there was at least - * one since the start of the grace period. Thus just a flag. - */ -static inline void rcu_qsctr_inc(int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - rdp->passed_quiesc = 1; -} -static inline void rcu_bh_qsctr_inc(int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); - rdp->passed_quiesc = 1; -} - -extern int rcu_pending(int cpu); -extern int rcu_needs_cpu(int cpu); - /** * rcu_read_lock - mark the beginning of an RCU read-side critical section. * @@ -163,22 +89,14 @@ extern int rcu_needs_cpu(int cpu); * * It is illegal to block while in an RCU read-side critical section. */ -#define rcu_read_lock() \ - do { \ - preempt_disable(); \ - __acquire(RCU); \ - } while(0) +#define rcu_read_lock() __rcu_read_lock() /** * rcu_read_unlock - marks the end of an RCU read-side critical section. * * See rcu_read_lock() for more information. */ -#define rcu_read_unlock() \ - do { \ - __release(RCU); \ - preempt_enable(); \ - } while(0) +#define rcu_read_unlock() __rcu_read_unlock() /* * So where is rcu_write_lock()? It does not exist, as there is no @@ -201,23 +119,15 @@ extern int rcu_needs_cpu(int cpu); * can use just rcu_read_lock(). * */ -#define rcu_read_lock_bh() \ - do { \ - local_bh_disable(); \ - __acquire(RCU_BH); \ - } while(0) - -/* +#define rcu_read_lock_bh() __rcu_read_lock_bh() + +/** * rcu_read_unlock_bh - marks the end of a softirq-only RCU critical section * * See rcu_read_lock_bh() for more information. */ -#define rcu_read_unlock_bh() \ - do { \ - __release(RCU_BH); \ - local_bh_enable(); \ - } while(0) - +#define rcu_read_unlock_bh() __rcu_read_unlock_bh() + /** * rcu_dereference - fetch an RCU-protected pointer in an * RCU read-side critical section. This pointer may later @@ -268,22 +178,49 @@ extern int rcu_needs_cpu(int cpu); * In "classic RCU", these two guarantees happen to be one and * the same, but can differ in realtime RCU implementations. */ -#define synchronize_sched() synchronize_rcu() +#define synchronize_sched() __synchronize_sched() + +/** + * call_rcu - Queue an RCU callback for invocation after a grace period. + * @head: structure to be used for queueing the RCU updates. + * @func: actual update function to be invoked after the grace period + * + * The update function will be invoked some time after a full grace + * period elapses, in other words after all currently executing RCU + * read-side critical sections have completed. RCU read-side critical + * sections are delimited by rcu_read_lock() and rcu_read_unlock(), + * and may be nested. + */ +extern void FASTCALL(call_rcu(struct rcu_head *head, + void (*func)(struct rcu_head *head))); -extern void rcu_init(void); -extern void rcu_check_callbacks(int cpu, int user); -extern void rcu_restart_cpu(int cpu); -extern long rcu_batches_completed(void); -extern long rcu_batches_completed_bh(void); -/* Exported interfaces */ -extern void FASTCALL(call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *head))); +/** + * call_rcu_bh - Queue an RCU for invocation after a quicker grace period. + * @head: structure to be used for queueing the RCU updates. + * @func: actual update function to be invoked after the grace period + * + * The update function will be invoked some time after a full grace + * period elapses, in other words after all currently executing RCU + * read-side critical sections have completed. call_rcu_bh() assumes + * that the read-side critical sections end on completion of a softirq + * handler. This means that read-side critical sections in process + * context must not be interrupted by softirqs. This interface is to be + * used when most of the read-side critical sections are in softirq context. + * RCU read-side critical sections are delimited by rcu_read_lock() and + * rcu_read_unlock(), * if in interrupt context or rcu_read_lock_bh() + * and rcu_read_unlock_bh(), if in process context. These may be nested. + */ extern void FASTCALL(call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *head))); + +/* Exported common interfaces */ extern void synchronize_rcu(void); -void synchronize_idle(void); extern void rcu_barrier(void); + +/* Internal to kernel */ +extern void rcu_init(void); +extern void rcu_check_callbacks(int cpu, int user); #endif /* __KERNEL__ */ #endif /* __LINUX_RCUPDATE_H */ diff -puN kernel/Makefile~rcu-split-classic kernel/Makefile --- linux-2.6.18-rc6-mm1-rcu/kernel/Makefile~rcu-split-classic 2006-09-23 03:27:38.000000000 +0530 +++ linux-2.6.18-rc6-mm1-rcu-dipankar/kernel/Makefile 2006-09-23 03:27:38.000000000 +0530 @@ -6,7 +6,7 @@ obj-y = sched.o fork.o exec_domain.o exit.o itimer.o time.o softirq.o resource.o \ sysctl.o capability.o ptrace.o timer.o user.o \ signal.o sys.o kmod.o workqueue.o pid.o \ - rcupdate.o extable.o params.o posix-timers.o \ + rcupdate.o rcuclassic.o extable.o params.o posix-timers.o \ kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \ hrtimer.o rwsem.o latency.o nsproxy.o srcu.o diff -puN /dev/null kernel/rcuclassic.c --- /dev/null 2006-09-20 22:20:57.873117750 +0530 +++ linux-2.6.18-rc6-mm1-rcu-dipankar/kernel/rcuclassic.c 2006-09-23 03:40:16.000000000 +0530 @@ -0,0 +1,558 @@ +/* + * Read-Copy Update mechanism for mutual exclusion, classic implementation + * + * 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 (C) IBM Corporation, 2001 + * + * Authors: Dipankar Sarma + * Manfred Spraul + * + * Based on the original work by Paul McKenney + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * + * Papers: http://www.rdrop.com/users/paulmck/RCU + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU/ *.txt + * + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +/* Definition for rcupdate control block. */ +static struct rcu_ctrlblk rcu_ctrlblk = { + .cur = -300, + .completed = -300, + .lock = SPIN_LOCK_UNLOCKED, + .cpumask = CPU_MASK_NONE, +}; +static struct rcu_ctrlblk rcu_bh_ctrlblk = { + .cur = -300, + .completed = -300, + .lock = SPIN_LOCK_UNLOCKED, + .cpumask = CPU_MASK_NONE, +}; + +DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L }; +DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; + +/* Fake initialization required by compiler */ +static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL}; +static int blimit = 10; +static int qhimark = 10000; +static int qlowmark = 100; +#ifdef CONFIG_SMP +static int rsinterval = 1000; +#endif + +#ifdef CONFIG_SMP +static void force_quiescent_state(struct rcu_data *rdp, + struct rcu_ctrlblk *rcp) +{ + int cpu; + cpumask_t cpumask; + set_need_resched(); + if (unlikely(rdp->qlen - rdp->last_rs_qlen > rsinterval)) { + rdp->last_rs_qlen = rdp->qlen; + /* + * Don't send IPI to itself. With irqs disabled, + * rdp->cpu is the current cpu. + */ + cpumask = rcp->cpumask; + cpu_clear(rdp->cpu, cpumask); + for_each_cpu_mask(cpu, cpumask) + smp_send_reschedule(cpu); + } +} +#else +static inline void force_quiescent_state(struct rcu_data *rdp, + struct rcu_ctrlblk *rcp) +{ + set_need_resched(); +} +#endif + +/* + * call_rcu - Queue an RCU callback for invocation after a grace period. + * @head: structure to be used for queueing the RCU updates. + * @func: actual update function to be invoked after the grace period + * + * The update function will be invoked some time after a full grace + * period elapses, in other words after all currently executing RCU + * read-side critical sections have completed. RCU read-side critical + * sections are delimited by rcu_read_lock() and rcu_read_unlock(), + * and may be nested. + */ +void fastcall call_rcu(struct rcu_head *head, + void (*func)(struct rcu_head *rcu)) +{ + unsigned long flags; + struct rcu_data *rdp; + + head->func = func; + head->next = NULL; + local_irq_save(flags); + rdp = &__get_cpu_var(rcu_data); + *rdp->nxttail = head; + rdp->nxttail = &head->next; + if (unlikely(++rdp->qlen > qhimark)) { + rdp->blimit = INT_MAX; + force_quiescent_state(rdp, &rcu_ctrlblk); + } + local_irq_restore(flags); +} + +/* + * call_rcu_bh - Queue an RCU for invocation after a quicker grace period. + * @head: structure to be used for queueing the RCU updates. + * @func: actual update function to be invoked after the grace period + * + * The update function will be invoked some time after a full grace + * period elapses, in other words after all currently executing RCU + * read-side critical sections have completed. call_rcu_bh() assumes + * that the read-side critical sections end on completion of a softirq + * handler. This means that read-side critical sections in process + * context must not be interrupted by softirqs. This interface is to be + * used when most of the read-side critical sections are in softirq context. + * RCU read-side critical sections are delimited by rcu_read_lock() and + * rcu_read_unlock(), * if in interrupt context or rcu_read_lock_bh() + * and rcu_read_unlock_bh(), if in process context. These may be nested. + */ +void fastcall call_rcu_bh(struct rcu_head *head, + void (*func)(struct rcu_head *rcu)) +{ + unsigned long flags; + struct rcu_data *rdp; + + head->func = func; + head->next = NULL; + local_irq_save(flags); + rdp = &__get_cpu_var(rcu_bh_data); + *rdp->nxttail = head; + rdp->nxttail = &head->next; + + if (unlikely(++rdp->qlen > qhimark)) { + rdp->blimit = INT_MAX; + force_quiescent_state(rdp, &rcu_bh_ctrlblk); + } + + local_irq_restore(flags); +} + +/* + * Return the number of RCU batches processed thus far. Useful + * for debug and statistics. + */ +long rcu_batches_completed(void) +{ + return rcu_ctrlblk.completed; +} + +/* + * Return the number of RCU batches processed thus far. Useful + * for debug and statistics. + */ +long rcu_batches_completed_bh(void) +{ + return rcu_bh_ctrlblk.completed; +} + +/* + * Invoke the completed RCU callbacks. They are expected to be in + * a per-cpu list. + */ +static void rcu_do_batch(struct rcu_data *rdp) +{ + struct rcu_head *next, *list; + int count = 0; + + list = rdp->donelist; + while (list) { + next = rdp->donelist = list->next; + list->func(list); + list = next; + rdp->qlen--; + if (++count >= rdp->blimit) + break; + } + if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark) + rdp->blimit = blimit; + if (!rdp->donelist) + rdp->donetail = &rdp->donelist; + else + tasklet_schedule(&per_cpu(rcu_tasklet, rdp->cpu)); +} + +/* + * Grace period handling: + * The grace period handling consists out of two steps: + * - A new grace period is started. + * This is done by rcu_start_batch. The start is not broadcasted to + * all cpus, they must pick this up by comparing rcp->cur with + * rdp->quiescbatch. All cpus are recorded in the + * rcu_ctrlblk.cpumask bitmap. + * - All cpus must go through a quiescent state. + * Since the start of the grace period is not broadcasted, at least two + * calls to rcu_check_quiescent_state are required: + * The first call just notices that a new grace period is running. The + * following calls check if there was a quiescent state since the beginning + * of the grace period. If so, it updates rcu_ctrlblk.cpumask. If + * the bitmap is empty, then the grace period is completed. + * rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace + * period (if necessary). + */ +/* + * Register a new batch of callbacks, and start it up if there is currently no + * active batch and the batch to be registered has not already occurred. + * Caller must hold rcu_ctrlblk.lock. + */ +static void rcu_start_batch(struct rcu_ctrlblk *rcp) +{ + if (rcp->next_pending && + rcp->completed == rcp->cur) { + rcp->next_pending = 0; + /* + * next_pending == 0 must be visible in + * __rcu_process_callbacks() before it can see new value of cur. + */ + smp_wmb(); + rcp->cur++; + + /* + * Accessing nohz_cpu_mask before incrementing rcp->cur needs a + * Barrier Otherwise it can cause tickless idle CPUs to be + * included in rcp->cpumask, which will extend graceperiods + * unnecessarily. + */ + smp_mb(); + cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask); + + } +} + +/* + * cpu went through a quiescent state since the beginning of the grace period. + * Clear it from the cpu mask and complete the grace period if it was the last + * cpu. Start another grace period if someone has further entries pending + */ +static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp) +{ + cpu_clear(cpu, rcp->cpumask); + if (cpus_empty(rcp->cpumask)) { + /* batch completed ! */ + rcp->completed = rcp->cur; + rcu_start_batch(rcp); + } +} + +/* + * Check if the cpu has gone through a quiescent state (say context + * switch). If so and if it already hasn't done so in this RCU + * quiescent cycle, then indicate that it has done so. + */ +static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, + struct rcu_data *rdp) +{ + if (rdp->quiescbatch != rcp->cur) { + /* start new grace period: */ + rdp->qs_pending = 1; + rdp->passed_quiesc = 0; + rdp->quiescbatch = rcp->cur; + return; + } + + /* Grace period already completed for this cpu? + * qs_pending is checked instead of the actual bitmap to avoid + * cacheline trashing. + */ + if (!rdp->qs_pending) + return; + + /* + * Was there a quiescent state since the beginning of the grace + * period? If no, then exit and wait for the next call. + */ + if (!rdp->passed_quiesc) + return; + rdp->qs_pending = 0; + + spin_lock(&rcp->lock); + /* + * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync + * during cpu startup. Ignore the quiescent state. + */ + if (likely(rdp->quiescbatch == rcp->cur)) + cpu_quiet(rdp->cpu, rcp); + + spin_unlock(&rcp->lock); +} + + +#ifdef CONFIG_HOTPLUG_CPU + +/* warning! helper for rcu_offline_cpu. do not use elsewhere without reviewing + * locking requirements, the list it's pulling from has to belong to a cpu + * which is dead and hence not processing interrupts. + */ +static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list, + struct rcu_head **tail) +{ + local_irq_disable(); + *this_rdp->nxttail = list; + if (list) + this_rdp->nxttail = tail; + local_irq_enable(); +} + +static void __rcu_offline_cpu(struct rcu_data *this_rdp, + struct rcu_ctrlblk *rcp, struct rcu_data *rdp) +{ + /* if the cpu going offline owns the grace period + * we can block indefinitely waiting for it, so flush + * it here + */ + spin_lock_bh(&rcp->lock); + if (rcp->cur != rcp->completed) + cpu_quiet(rdp->cpu, rcp); + spin_unlock_bh(&rcp->lock); + rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail); + rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail); + rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail); +} + +static void rcu_offline_cpu(int cpu) +{ + struct rcu_data *this_rdp = &get_cpu_var(rcu_data); + struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data); + + __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, + &per_cpu(rcu_data, cpu)); + __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, + &per_cpu(rcu_bh_data, cpu)); + put_cpu_var(rcu_data); + put_cpu_var(rcu_bh_data); + tasklet_kill_immediate(&per_cpu(rcu_tasklet, cpu), cpu); +} + +#else + +static void rcu_offline_cpu(int cpu) +{ +} + +#endif + +/* + * This does the RCU processing work from tasklet context. + */ +static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, + struct rcu_data *rdp) +{ + if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) { + *rdp->donetail = rdp->curlist; + rdp->donetail = rdp->curtail; + rdp->curlist = NULL; + rdp->curtail = &rdp->curlist; + } + + if (rdp->nxtlist && !rdp->curlist) { + local_irq_disable(); + rdp->curlist = rdp->nxtlist; + rdp->curtail = rdp->nxttail; + rdp->nxtlist = NULL; + rdp->nxttail = &rdp->nxtlist; + local_irq_enable(); + + /* + * start the next batch of callbacks + */ + + /* determine batch number */ + rdp->batch = rcp->cur + 1; + /* see the comment and corresponding wmb() in + * the rcu_start_batch() + */ + smp_rmb(); + + if (!rcp->next_pending) { + /* and start it/schedule start if it's a new batch */ + spin_lock(&rcp->lock); + rcp->next_pending = 1; + rcu_start_batch(rcp); + spin_unlock(&rcp->lock); + } + } + + rcu_check_quiescent_state(rcp, rdp); + if (rdp->donelist) + rcu_do_batch(rdp); +} + +static void rcu_process_callbacks(unsigned long unused) +{ + __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data)); + __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); +} + +static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp) +{ + /* This cpu has pending rcu entries and the grace period + * for them has completed. + */ + if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) + return 1; + + /* This cpu has no pending entries, but there are new entries */ + if (!rdp->curlist && rdp->nxtlist) + return 1; + + /* This cpu has finished callbacks to invoke */ + if (rdp->donelist) + return 1; + + /* The rcu core waits for a quiescent state from the cpu */ + if (rdp->quiescbatch != rcp->cur || rdp->qs_pending) + return 1; + + /* nothing to do */ + return 0; +} + +/* + * Check to see if there is any immediate RCU-related work to be done + * by the current CPU, returning 1 if so. This function is part of the + * RCU implementation; it is -not- an exported member of the RCU API. + */ +int rcu_pending(int cpu) +{ + return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) || + __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu)); +} + +/* + * Check to see if any future RCU-related work will need to be done + * by the current CPU, even if none need be done immediately, returning + * 1 if so. This function is part of the RCU implementation; it is -not- + * an exported member of the RCU API. + */ +int rcu_needs_cpu(int cpu) +{ + struct rcu_data *rdp = &per_cpu(rcu_data, cpu); + struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu); + + return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu)); +} + +void rcu_check_callbacks(int cpu, int user) +{ + if (user || + (idle_cpu(cpu) && !in_softirq() && + hardirq_count() <= (1 << HARDIRQ_SHIFT))) { + rcu_qsctr_inc(cpu); + rcu_bh_qsctr_inc(cpu); + } else if (!in_softirq()) + rcu_bh_qsctr_inc(cpu); + tasklet_schedule(&per_cpu(rcu_tasklet, cpu)); +} + +static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp, + struct rcu_data *rdp) +{ + memset(rdp, 0, sizeof(*rdp)); + rdp->curtail = &rdp->curlist; + rdp->nxttail = &rdp->nxtlist; + rdp->donetail = &rdp->donelist; + rdp->quiescbatch = rcp->completed; + rdp->qs_pending = 0; + rdp->cpu = cpu; + rdp->blimit = blimit; +} + +static void __devinit rcu_online_cpu(int cpu) +{ + struct rcu_data *rdp = &per_cpu(rcu_data, cpu); + struct rcu_data *bh_rdp = &per_cpu(rcu_bh_data, cpu); + + rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp); + rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp); + tasklet_init(&per_cpu(rcu_tasklet, cpu), rcu_process_callbacks, 0UL); +} + +static int __cpuinit rcu_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + long cpu = (long)hcpu; + switch (action) { + case CPU_UP_PREPARE: + rcu_online_cpu(cpu); + break; + case CPU_DEAD: + rcu_offline_cpu(cpu); + break; + default: + break; + } + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata rcu_nb = { + .notifier_call = rcu_cpu_notify, +}; + +/* + * Initializes rcu mechanism. Assumed to be called early. + * That is before local timer(SMP) or jiffie timer (uniproc) is setup. + * Note that rcu_qsctr and friends are implicitly + * initialized due to the choice of ``0'' for RCU_CTR_INVALID. + */ +void __init __rcu_init(void) +{ + rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, + (void *)(long)smp_processor_id()); + /* Register notifier for non-boot CPUs */ + register_cpu_notifier(&rcu_nb); +} + +module_param(blimit, int, 0); +module_param(qhimark, int, 0); +module_param(qlowmark, int, 0); +#ifdef CONFIG_SMP +module_param(rsinterval, int, 0); +#endif + +EXPORT_SYMBOL_GPL(rcu_batches_completed); +EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); +EXPORT_SYMBOL_GPL(call_rcu); +EXPORT_SYMBOL_GPL(call_rcu_bh); diff -puN kernel/rcupdate.c~rcu-split-classic kernel/rcupdate.c --- linux-2.6.18-rc6-mm1-rcu/kernel/rcupdate.c~rcu-split-classic 2006-09-23 03:27:38.000000000 +0530 +++ linux-2.6.18-rc6-mm1-rcu-dipankar/kernel/rcupdate.c 2006-09-23 03:40:36.000000000 +0530 @@ -40,155 +40,53 @@ #include #include #include -#include #include -#include #include -#include -#include #include #include +#include -/* Definition for rcupdate control block. */ -static struct rcu_ctrlblk rcu_ctrlblk = { - .cur = -300, - .completed = -300, - .lock = __SPIN_LOCK_UNLOCKED(&rcu_ctrlblk.lock), - .cpumask = CPU_MASK_NONE, -}; -static struct rcu_ctrlblk rcu_bh_ctrlblk = { - .cur = -300, - .completed = -300, - .lock = __SPIN_LOCK_UNLOCKED(&rcu_bh_ctrlblk.lock), - .cpumask = CPU_MASK_NONE, +struct rcu_synchronize { + struct rcu_head head; + struct completion completion; }; -DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L }; -DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; - -/* Fake initialization required by compiler */ -static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL}; -static int blimit = 10; -static int qhimark = 10000; -static int qlowmark = 100; -#ifdef CONFIG_SMP -static int rsinterval = 1000; -#endif - +static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head); static atomic_t rcu_barrier_cpu_count; static DEFINE_MUTEX(rcu_barrier_mutex); static struct completion rcu_barrier_completion; -#ifdef CONFIG_SMP -static void force_quiescent_state(struct rcu_data *rdp, - struct rcu_ctrlblk *rcp) -{ - int cpu; - cpumask_t cpumask; - set_need_resched(); - if (unlikely(rdp->qlen - rdp->last_rs_qlen > rsinterval)) { - rdp->last_rs_qlen = rdp->qlen; - /* - * Don't send IPI to itself. With irqs disabled, - * rdp->cpu is the current cpu. - */ - cpumask = rcp->cpumask; - cpu_clear(rdp->cpu, cpumask); - for_each_cpu_mask(cpu, cpumask) - smp_send_reschedule(cpu); - } -} -#else -static inline void force_quiescent_state(struct rcu_data *rdp, - struct rcu_ctrlblk *rcp) +/* Because of FASTCALL declaration of complete, we use this wrapper */ +static void wakeme_after_rcu(struct rcu_head *head) { - set_need_resched(); + struct rcu_synchronize *rcu; + + rcu = container_of(head, struct rcu_synchronize, head); + complete(&rcu->completion); } -#endif /** - * call_rcu - Queue an RCU callback for invocation after a grace period. - * @head: structure to be used for queueing the RCU updates. - * @func: actual update function to be invoked after the grace period + * synchronize_rcu - wait until a grace period has elapsed. * - * The update function will be invoked some time after a full grace - * period elapses, in other words after all currently executing RCU + * Control will return to the caller some time after a full grace + * period has elapsed, in other words after all currently executing RCU * read-side critical sections have completed. RCU read-side critical * sections are delimited by rcu_read_lock() and rcu_read_unlock(), * and may be nested. - */ -void fastcall call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *rcu)) -{ - unsigned long flags; - struct rcu_data *rdp; - - head->func = func; - head->next = NULL; - local_irq_save(flags); - rdp = &__get_cpu_var(rcu_data); - *rdp->nxttail = head; - rdp->nxttail = &head->next; - if (unlikely(++rdp->qlen > qhimark)) { - rdp->blimit = INT_MAX; - force_quiescent_state(rdp, &rcu_ctrlblk); - } - local_irq_restore(flags); -} - -/** - * call_rcu_bh - Queue an RCU for invocation after a quicker grace period. - * @head: structure to be used for queueing the RCU updates. - * @func: actual update function to be invoked after the grace period * - * The update function will be invoked some time after a full grace - * period elapses, in other words after all currently executing RCU - * read-side critical sections have completed. call_rcu_bh() assumes - * that the read-side critical sections end on completion of a softirq - * handler. This means that read-side critical sections in process - * context must not be interrupted by softirqs. This interface is to be - * used when most of the read-side critical sections are in softirq context. - * RCU read-side critical sections are delimited by rcu_read_lock() and - * rcu_read_unlock(), * if in interrupt context or rcu_read_lock_bh() - * and rcu_read_unlock_bh(), if in process context. These may be nested. - */ -void fastcall call_rcu_bh(struct rcu_head *head, - void (*func)(struct rcu_head *rcu)) -{ - unsigned long flags; - struct rcu_data *rdp; - - head->func = func; - head->next = NULL; - local_irq_save(flags); - rdp = &__get_cpu_var(rcu_bh_data); - *rdp->nxttail = head; - rdp->nxttail = &head->next; - - if (unlikely(++rdp->qlen > qhimark)) { - rdp->blimit = INT_MAX; - force_quiescent_state(rdp, &rcu_bh_ctrlblk); - } - - local_irq_restore(flags); -} - -/* - * Return the number of RCU batches processed thus far. Useful - * for debug and statistics. - */ -long rcu_batches_completed(void) -{ - return rcu_ctrlblk.completed; -} - -/* - * Return the number of RCU batches processed thus far. Useful - * for debug and statistics. + * If your read-side code is not protected by rcu_read_lock(), do -not- + * use synchronize_rcu(). */ -long rcu_batches_completed_bh(void) +void synchronize_rcu(void) { - return rcu_bh_ctrlblk.completed; + 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); } static void rcu_barrier_callback(struct rcu_head *notused) @@ -203,10 +101,8 @@ static void rcu_barrier_callback(struct static void rcu_barrier_func(void *notused) { int cpu = smp_processor_id(); - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - struct rcu_head *head; + struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); - head = &rdp->barrier; atomic_inc(&rcu_barrier_cpu_count); call_rcu(head, rcu_barrier_callback); } @@ -225,410 +121,12 @@ void rcu_barrier(void) wait_for_completion(&rcu_barrier_completion); mutex_unlock(&rcu_barrier_mutex); } -EXPORT_SYMBOL_GPL(rcu_barrier); - -/* - * Invoke the completed RCU callbacks. They are expected to be in - * a per-cpu list. - */ -static void rcu_do_batch(struct rcu_data *rdp) -{ - struct rcu_head *next, *list; - int count = 0; - - list = rdp->donelist; - while (list) { - next = rdp->donelist = list->next; - list->func(list); - list = next; - rdp->qlen--; - if (++count >= rdp->blimit) - break; - } - if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark) - rdp->blimit = blimit; - if (!rdp->donelist) - rdp->donetail = &rdp->donelist; - else - tasklet_schedule(&per_cpu(rcu_tasklet, rdp->cpu)); -} - -/* - * Grace period handling: - * The grace period handling consists out of two steps: - * - A new grace period is started. - * This is done by rcu_start_batch. The start is not broadcasted to - * all cpus, they must pick this up by comparing rcp->cur with - * rdp->quiescbatch. All cpus are recorded in the - * rcu_ctrlblk.cpumask bitmap. - * - All cpus must go through a quiescent state. - * Since the start of the grace period is not broadcasted, at least two - * calls to rcu_check_quiescent_state are required: - * The first call just notices that a new grace period is running. The - * following calls check if there was a quiescent state since the beginning - * of the grace period. If so, it updates rcu_ctrlblk.cpumask. If - * the bitmap is empty, then the grace period is completed. - * rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace - * period (if necessary). - */ -/* - * Register a new batch of callbacks, and start it up if there is currently no - * active batch and the batch to be registered has not already occurred. - * Caller must hold rcu_ctrlblk.lock. - */ -static void rcu_start_batch(struct rcu_ctrlblk *rcp) -{ - if (rcp->next_pending && - rcp->completed == rcp->cur) { - rcp->next_pending = 0; - /* - * next_pending == 0 must be visible in - * __rcu_process_callbacks() before it can see new value of cur. - */ - smp_wmb(); - rcp->cur++; - - /* - * Accessing nohz_cpu_mask before incrementing rcp->cur needs a - * Barrier Otherwise it can cause tickless idle CPUs to be - * included in rcp->cpumask, which will extend graceperiods - * unnecessarily. - */ - smp_mb(); - cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask); - - } -} - -/* - * cpu went through a quiescent state since the beginning of the grace period. - * Clear it from the cpu mask and complete the grace period if it was the last - * cpu. Start another grace period if someone has further entries pending - */ -static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp) -{ - cpu_clear(cpu, rcp->cpumask); - if (cpus_empty(rcp->cpumask)) { - /* batch completed ! */ - rcp->completed = rcp->cur; - rcu_start_batch(rcp); - } -} - -/* - * Check if the cpu has gone through a quiescent state (say context - * switch). If so and if it already hasn't done so in this RCU - * quiescent cycle, then indicate that it has done so. - */ -static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, - struct rcu_data *rdp) -{ - if (rdp->quiescbatch != rcp->cur) { - /* start new grace period: */ - rdp->qs_pending = 1; - rdp->passed_quiesc = 0; - rdp->quiescbatch = rcp->cur; - return; - } - - /* Grace period already completed for this cpu? - * qs_pending is checked instead of the actual bitmap to avoid - * cacheline trashing. - */ - if (!rdp->qs_pending) - return; - - /* - * Was there a quiescent state since the beginning of the grace - * period? If no, then exit and wait for the next call. - */ - if (!rdp->passed_quiesc) - return; - rdp->qs_pending = 0; - - spin_lock(&rcp->lock); - /* - * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync - * during cpu startup. Ignore the quiescent state. - */ - if (likely(rdp->quiescbatch == rcp->cur)) - cpu_quiet(rdp->cpu, rcp); - - spin_unlock(&rcp->lock); -} - - -#ifdef CONFIG_HOTPLUG_CPU - -/* warning! helper for rcu_offline_cpu. do not use elsewhere without reviewing - * locking requirements, the list it's pulling from has to belong to a cpu - * which is dead and hence not processing interrupts. - */ -static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list, - struct rcu_head **tail) -{ - local_irq_disable(); - *this_rdp->nxttail = list; - if (list) - this_rdp->nxttail = tail; - local_irq_enable(); -} - -static void __rcu_offline_cpu(struct rcu_data *this_rdp, - struct rcu_ctrlblk *rcp, struct rcu_data *rdp) -{ - /* if the cpu going offline owns the grace period - * we can block indefinitely waiting for it, so flush - * it here - */ - spin_lock_bh(&rcp->lock); - if (rcp->cur != rcp->completed) - cpu_quiet(rdp->cpu, rcp); - spin_unlock_bh(&rcp->lock); - rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail); - rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail); - rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail); -} - -static void rcu_offline_cpu(int cpu) -{ - struct rcu_data *this_rdp = &get_cpu_var(rcu_data); - struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data); - - __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, - &per_cpu(rcu_data, cpu)); - __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, - &per_cpu(rcu_bh_data, cpu)); - put_cpu_var(rcu_data); - put_cpu_var(rcu_bh_data); - tasklet_kill_immediate(&per_cpu(rcu_tasklet, cpu), cpu); -} - -#else -static void rcu_offline_cpu(int cpu) -{ -} - -#endif - -/* - * This does the RCU processing work from tasklet context. - */ -static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, - struct rcu_data *rdp) -{ - if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) { - *rdp->donetail = rdp->curlist; - rdp->donetail = rdp->curtail; - rdp->curlist = NULL; - rdp->curtail = &rdp->curlist; - } - - if (rdp->nxtlist && !rdp->curlist) { - local_irq_disable(); - rdp->curlist = rdp->nxtlist; - rdp->curtail = rdp->nxttail; - rdp->nxtlist = NULL; - rdp->nxttail = &rdp->nxtlist; - local_irq_enable(); - - /* - * start the next batch of callbacks - */ - - /* determine batch number */ - rdp->batch = rcp->cur + 1; - /* see the comment and corresponding wmb() in - * the rcu_start_batch() - */ - smp_rmb(); - - if (!rcp->next_pending) { - /* and start it/schedule start if it's a new batch */ - spin_lock(&rcp->lock); - rcp->next_pending = 1; - rcu_start_batch(rcp); - spin_unlock(&rcp->lock); - } - } - - rcu_check_quiescent_state(rcp, rdp); - if (rdp->donelist) - rcu_do_batch(rdp); -} - -static void rcu_process_callbacks(unsigned long unused) -{ - __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data)); - __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); -} - -static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp) -{ - /* This cpu has pending rcu entries and the grace period - * for them has completed. - */ - if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) - return 1; - - /* This cpu has no pending entries, but there are new entries */ - if (!rdp->curlist && rdp->nxtlist) - return 1; - - /* This cpu has finished callbacks to invoke */ - if (rdp->donelist) - return 1; - - /* The rcu core waits for a quiescent state from the cpu */ - if (rdp->quiescbatch != rcp->cur || rdp->qs_pending) - return 1; - - /* nothing to do */ - return 0; -} - -/* - * Check to see if there is any immediate RCU-related work to be done - * by the current CPU, returning 1 if so. This function is part of the - * RCU implementation; it is -not- an exported member of the RCU API. - */ -int rcu_pending(int cpu) -{ - return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) || - __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu)); -} - -/* - * Check to see if any future RCU-related work will need to be done - * by the current CPU, even if none need be done immediately, returning - * 1 if so. This function is part of the RCU implementation; it is -not- - * an exported member of the RCU API. - */ -int rcu_needs_cpu(int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu); - - return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu)); -} - -void rcu_check_callbacks(int cpu, int user) -{ - if (user || - (idle_cpu(cpu) && !in_softirq() && - hardirq_count() <= (1 << HARDIRQ_SHIFT))) { - rcu_qsctr_inc(cpu); - rcu_bh_qsctr_inc(cpu); - } else if (!in_softirq()) - rcu_bh_qsctr_inc(cpu); - tasklet_schedule(&per_cpu(rcu_tasklet, cpu)); -} - -static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp, - struct rcu_data *rdp) -{ - memset(rdp, 0, sizeof(*rdp)); - rdp->curtail = &rdp->curlist; - rdp->nxttail = &rdp->nxtlist; - rdp->donetail = &rdp->donelist; - rdp->quiescbatch = rcp->completed; - rdp->qs_pending = 0; - rdp->cpu = cpu; - rdp->blimit = blimit; -} - -static void __devinit rcu_online_cpu(int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - struct rcu_data *bh_rdp = &per_cpu(rcu_bh_data, cpu); - - rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp); - rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp); - tasklet_init(&per_cpu(rcu_tasklet, cpu), rcu_process_callbacks, 0UL); -} - -static int __cpuinit rcu_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu) -{ - long cpu = (long)hcpu; - switch (action) { - case CPU_UP_PREPARE: - rcu_online_cpu(cpu); - break; - case CPU_DEAD: - rcu_offline_cpu(cpu); - break; - default: - break; - } - return NOTIFY_OK; -} - -static struct notifier_block __cpuinitdata rcu_nb = { - .notifier_call = rcu_cpu_notify, -}; - -/* - * Initializes rcu mechanism. Assumed to be called early. - * That is before local timer(SMP) or jiffie timer (uniproc) is setup. - * Note that rcu_qsctr and friends are implicitly - * initialized due to the choice of ``0'' for RCU_CTR_INVALID. - */ void __init rcu_init(void) { - rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, - (void *)(long)smp_processor_id()); - /* Register notifier for non-boot CPUs */ - register_cpu_notifier(&rcu_nb); -} - -struct rcu_synchronize { - struct rcu_head head; - struct completion completion; -}; - -/* Because of FASTCALL declaration of complete, we use this wrapper */ -static void wakeme_after_rcu(struct rcu_head *head) -{ - struct rcu_synchronize *rcu; - - rcu = container_of(head, struct rcu_synchronize, head); - complete(&rcu->completion); -} - -/** - * synchronize_rcu - wait until a grace period has elapsed. - * - * Control will return to the caller some time after a full grace - * period has elapsed, in other words after all currently executing RCU - * read-side critical sections have completed. RCU read-side critical - * sections are delimited by rcu_read_lock() and rcu_read_unlock(), - * and may be nested. - * - * If your read-side code is not protected by rcu_read_lock(), do -not- - * use synchronize_rcu(). - */ -void synchronize_rcu(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); + __rcu_init(); } - -module_param(blimit, int, 0); -module_param(qhimark, int, 0); -module_param(qlowmark, int, 0); -#ifdef CONFIG_SMP -module_param(rsinterval, int, 0); -#endif -EXPORT_SYMBOL_GPL(rcu_batches_completed); -EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); -EXPORT_SYMBOL_GPL(call_rcu); -EXPORT_SYMBOL_GPL(call_rcu_bh); + +EXPORT_SYMBOL_GPL(rcu_barrier); EXPORT_SYMBOL_GPL(synchronize_rcu); +