diff -urN linux-2.5.8-base/include/linux/init_task.h linux-2.5.8-rcu/include/linux/init_task.h --- linux-2.5.8-base/include/linux/init_task.h Mon Apr 15 00:48:45 2002 +++ linux-2.5.8-rcu/include/linux/init_task.h Wed Apr 17 14:47:02 2002 @@ -79,6 +79,7 @@ blocked: {{0}}, \ alloc_lock: SPIN_LOCK_UNLOCKED, \ journal_info: NULL, \ + cpu_preempt_cntr: NULL, \ } diff -urN linux-2.5.8-base/include/linux/rcupdate.h linux-2.5.8-rcu/include/linux/rcupdate.h --- linux-2.5.8-base/include/linux/rcupdate.h Thu Jan 1 05:30:00 1970 +++ linux-2.5.8-rcu/include/linux/rcupdate.h Wed Apr 17 14:38:14 2002 @@ -0,0 +1,73 @@ +/* + * Read-Copy Update mechanism for mutual exclusion + * + * 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) International Business Machines Corp., 2001 + * + * Author: Dipankar Sarma + * + * Based on the original work by Paul McKenney + * and inputs from Andrea Arcangeli, Rusty Russell, Andi Kleen etc. + * 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_RCUPDATE_H +#define __LINUX_RCUPDATE_H + +#include +#include + +/* + * Callback structure for use with call_rcu(). + */ +struct rcu_head { + struct list_head list; + void (*func)(void *obj); + void *arg; +}; + +#define RCU_HEAD_INIT(head) { LIST_HEAD_INIT(head.list), NULL, NULL } +#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT(head) +#define INIT_RCU_HEAD(ptr) do { \ + INIT_LIST_HEAD(&(ptr)->list); (ptr)->func = NULL; (ptr)->arg = NULL; \ +} while (0) + +/* Batch counter type. */ +typedef long rcu_batch_t; + +/* + * RCU_BATCH_XX(rcu_batch_t a, rcu_batch_t b) + * + * Returns true if batch number ``a'' compares as specified to ``b''. + * This comparison allows for the fact that the batch numbers wrap. + */ +#define RCU_BATCH_EQ(a, b) ((a) - (b) == 0) +#define RCU_BATCH_GE(a, b) ((a) - (b) >= 0) +#define RCU_BATCH_GT(a, b) ((a) - (b) > 0) +#define RCU_BATCH_LE(a, b) ((a) - (b) <= 0) +#define RCU_BATCH_LT(a, b) ((a) - (b) < 0) +#define RCU_BATCH_NE(a, b) ((a) - (b) != 0) + +extern void call_rcu(struct rcu_head *head, void (*func)(void *arg), void *arg); +extern void synchronize_kernel(void); + +#endif /* __LINUX_RCUPDATE_H */ diff -urN linux-2.5.8-base/include/linux/sched.h linux-2.5.8-rcu/include/linux/sched.h --- linux-2.5.8-base/include/linux/sched.h Mon Apr 15 00:48:45 2002 +++ linux-2.5.8-rcu/include/linux/sched.h Fri Apr 19 22:10:43 2002 @@ -28,6 +28,7 @@ #include #include #include +#include struct exec_domain; @@ -346,6 +347,7 @@ /* journalling filesystem info */ void *journal_info; + atomic_t *cpu_preempt_cntr; }; extern void __put_task_struct(struct task_struct *tsk); @@ -418,6 +420,7 @@ extern struct mm_struct init_mm; extern struct task_struct *init_tasks[NR_CPUS]; +extern long cpu_quiescent __per_cpu_data; /* PID hashing. (shouldnt this be dynamic?) */ #define PIDHASH_SZ (4096 >> 2) @@ -883,6 +886,53 @@ clear_thread_flag(TIF_SIGPENDING); } +#ifdef CONFIG_PREEMPT + +extern atomic_t rcu_preempt_cntr[2] __per_cpu_data; +extern atomic_t *curr_preempt_cntr __per_cpu_data; +extern atomic_t *next_preempt_cntr __per_cpu_data; + +static inline void rcu_switch_preempt_cntr(int cpu) +{ + atomic_t *tmp; + tmp = per_cpu(curr_preempt_cntr, cpu); + per_cpu(curr_preempt_cntr, cpu) = per_cpu(next_preempt_cntr, cpu); + per_cpu(next_preempt_cntr, cpu) = tmp; + +} + +static inline void rcu_preempt_put(void) +{ + if (unlikely(current->cpu_preempt_cntr != NULL)) { + atomic_dec(current->cpu_preempt_cntr); + current->cpu_preempt_cntr = NULL; + } +} + +/* Must not be preempted */ +static inline void rcu_preempt_get(void) +{ + if (likely(current->cpu_preempt_cntr == NULL)) { + current->cpu_preempt_cntr = + this_cpu(next_preempt_cntr); + atomic_inc(current->cpu_preempt_cntr); + } +} + +static inline int rcu_cpu_preempted(int cpu) +{ + return (atomic_read(per_cpu(curr_preempt_cntr, cpu)) != 0); +} +#else + +#define rcu_init_preempt_cntr(cpu) do { } while(0) +#define rcu_switch_preempt_cntr(cpu) do { } while(0) +#define rcu_preempt_put() do { } while(0) +#define rcu_preempt_get() do { } while(0) +#define rcu_cpu_preempted(cpu) (0) + +#endif + #endif /* __KERNEL__ */ #endif diff -urN linux-2.5.8-base/kernel/Makefile linux-2.5.8-rcu/kernel/Makefile --- linux-2.5.8-base/kernel/Makefile Mon Apr 15 00:48:47 2002 +++ linux-2.5.8-rcu/kernel/Makefile Tue Apr 16 12:32:09 2002 @@ -10,12 +10,12 @@ O_TARGET := kernel.o export-objs = signal.o sys.o kmod.o context.o ksyms.o pm.o exec_domain.o \ - printk.o platform.o + printk.o platform.o rcupdate.o obj-y = sched.o dma.o fork.o exec_domain.o panic.o printk.o \ module.o exit.o itimer.o info.o time.o softirq.o resource.o \ sysctl.o capability.o ptrace.o timer.o user.o \ - signal.o sys.o kmod.o context.o futex.o platform.o + signal.o sys.o kmod.o context.o futex.o platform.o rcupdate.o obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += ksyms.o diff -urN linux-2.5.8-base/kernel/exit.c linux-2.5.8-rcu/kernel/exit.c --- linux-2.5.8-base/kernel/exit.c Mon Apr 15 00:48:49 2002 +++ linux-2.5.8-rcu/kernel/exit.c Wed Apr 17 11:25:01 2002 @@ -518,6 +518,7 @@ tsk->exit_code = code; exit_notify(); + rcu_preempt_put(); schedule(); BUG(); /* diff -urN linux-2.5.8-base/kernel/rcupdate.c linux-2.5.8-rcu/kernel/rcupdate.c --- linux-2.5.8-base/kernel/rcupdate.c Thu Jan 1 05:30:00 1970 +++ linux-2.5.8-rcu/kernel/rcupdate.c Fri Apr 19 16:59:03 2002 @@ -0,0 +1,393 @@ +/* + * Read-Copy Update mechanism for mutual exclusion + * + * 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) International Business Machines Corp., 2001 + * + * Author: Dipankar Sarma + * + * Based on the original work by Paul McKenney + * and inputs from Andrea Arcangeli, Rusty Russell, Andi Kleen etc. + * + * 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 + * + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Per-CPU data for Read-Copy UPdate. + * We maintain callbacks in 3 per-cpu lists. Each list represents + * a batch and every batch is given a number that is global across + * all CPUs. The global current batch number (curbatch) represents + * the current batch of callbacks for which the quiescent cycle + * has started. + * rcu_nextlist - new callbacks are added here + * rcu_currlist - current batch for which quiescent cycle started if any + * rcu_donelist - one or more batches that have finished waiting to be invoked + */ + +static long rcu_last_qsctr __per_cpu_data; +static rcu_batch_t rcu_batch __per_cpu_data; +static struct list_head rcu_nextlist __per_cpu_data; +struct list_head rcu_currlist __per_cpu_data; +struct list_head rcu_donelist __per_cpu_data; +struct tasklet_struct rcu_tasklet __per_cpu_data; +struct task_struct *rcu_task __per_cpu_data; +struct semaphore rcu_sema __per_cpu_data; + +#define RCU_QSCTR_INVALID 0 + +static spinlock_t rcu_lock = SPIN_LOCK_UNLOCKED; +static rcu_batch_t rcu_curbatch = 1; /* Current batch number */ +static rcu_batch_t rcu_maxbatch = 1; /* Max requested batch number*/ + + +/* CPUs that need to switch in order for current RCU batch to proceed */ +static unsigned long rcu_cpumask = 0; +/* CPUs that have active RCUs */ +static unsigned long rcu_active_cpumask = 0; +/* Global timer to nudge CPUs */ +static struct timer_list rcu_timer; + +asmlinkage long sys_sched_get_priority_max(int policy); + +/* + * Register a new rcu callback. This will be invoked as soon + * as all CPUs have performed a context switch or been seen in the + * idle loop or in a user process. + */ +void call_rcu(struct rcu_head *head, void (*func)(void *arg), void *arg) +{ + unsigned long flags; + + head->func = func; + head->arg = arg; + local_irq_save(flags); + list_add_tail(&head->list, &this_cpu(rcu_nextlist)); + local_irq_restore(flags); + tasklet_schedule(&this_cpu(rcu_tasklet)); +} + +/* + * Invoke the completed RCU callbacks. They are expected to be in + * a per-cpu list. + */ +static inline void rcu_invoke_callbacks(struct list_head *list) +{ + struct list_head *entry; + struct rcu_head *head; + + while (!list_empty(list)) { + entry = list->next; + list_del(entry); + head = list_entry(entry, struct rcu_head, list); + head->func(head->arg); + } +} + +/* + * Register a new batch of callbacks with the global state maintainers. + * Caller must hold the rcu global lock. + */ +static inline void rcu_reg_batch(rcu_batch_t newbatch) +{ + int cpu = cpu_number_map(smp_processor_id()); + + if (RCU_BATCH_LT(rcu_maxbatch, newbatch)) { + rcu_maxbatch = newbatch; + } + if (RCU_BATCH_LT(rcu_maxbatch, rcu_curbatch) || (rcu_cpumask != 0)) { + return; + } + rcu_cpumask = cpu_online_map; + rcu_switch_preempt_cntr(cpu); +} + +/* + * Check if the cpu has gone through a quiescent state. + * 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(void) +{ + int cpu = cpu_number_map(smp_processor_id()); + + if (!test_bit(cpu, &rcu_cpumask)) { + return; + } + + /* + * May race with rcu per-cpu tick - in the worst case + * we may miss one quiescent state of that CPU. That is + * tolerable. So no need to disable interrupts. + */ + if (this_cpu(rcu_last_qsctr) == RCU_QSCTR_INVALID) { + this_cpu(rcu_last_qsctr) = this_cpu(cpu_quiescent); + return; + } + if (this_cpu(cpu_quiescent) == this_cpu(rcu_last_qsctr) || + rcu_cpu_preempted(cpu)) { + return; + } + + spin_lock(&rcu_lock); + if (!test_bit(cpu, &rcu_cpumask)) { + spin_unlock(&rcu_lock); + return; + } + clear_bit(cpu, &rcu_cpumask); + this_cpu(rcu_last_qsctr) = RCU_QSCTR_INVALID; + if (rcu_cpumask != 0) { + /* All CPUs haven't gone through a quiescent state */ + spin_unlock(&rcu_lock); + return; + } + rcu_curbatch++; + rcu_reg_batch(rcu_maxbatch); + spin_unlock(&rcu_lock); +} + +static void rcu_move_next_batch(void) +{ + int rcu_timer_active; + int cpu = cpu_number_map(smp_processor_id()); + + local_irq_disable(); + if (!list_empty(&this_cpu(rcu_nextlist)) && + list_empty(&this_cpu(rcu_currlist))) { + list_splice(&this_cpu(rcu_nextlist), &this_cpu(rcu_currlist)); + INIT_LIST_HEAD(&this_cpu(rcu_nextlist)); + local_irq_enable(); + + /* + * start the next batch of callbacks + */ + spin_lock(&rcu_lock); + rcu_timer_active = (rcu_active_cpumask != 0); + if (!test_bit(cpu, &rcu_active_cpumask)) + set_bit(cpu, &rcu_active_cpumask); + if (!rcu_timer_active && + !timer_pending(&rcu_timer)) { + rcu_timer.expires = jiffies + 5; + add_timer(&rcu_timer); + } + this_cpu(rcu_batch) = rcu_curbatch + 1; + rcu_reg_batch(this_cpu(rcu_batch)); + spin_unlock(&rcu_lock); + } else { + local_irq_enable(); + } +} + +/* + * Look into the per-cpu callback information to see if there is + * any processing necessary - if so do it. + */ +static void rcu_process_callbacks(unsigned long data) +{ + int cpu = cpu_number_map(smp_processor_id()); + + if (!list_empty(&this_cpu(rcu_currlist)) && + RCU_BATCH_GT(rcu_curbatch, this_cpu(rcu_batch))) { + list_splice(&this_cpu(rcu_currlist), &this_cpu(rcu_donelist)); + INIT_LIST_HEAD(&this_cpu(rcu_currlist)); + } + + rcu_move_next_batch(); + + /* + * No race between nxtlist here & call_rcu() from irq - + * call_rcu() will anyway reschedule the tasklet so if the + * bit in cpu_active_mask gets cleared, it will get set again. + */ + if (list_empty(&this_cpu(rcu_nextlist)) && + list_empty(&this_cpu(rcu_currlist))) { + spin_lock(&rcu_lock); + clear_bit(cpu, &rcu_active_cpumask); + spin_unlock(&rcu_lock); + } + rcu_check_quiescent_state(); + + if (!list_empty(&this_cpu(rcu_donelist))) { + rcu_invoke_callbacks(&this_cpu(rcu_donelist)); + } +} + +/* + * Per-cpu tick that processes per-cpu queues + */ +static void rcu_percpu_tick_common(void) +{ + /* Take this opportunity to check for idle loop */ + if (idle_cpu(smp_processor_id())) + this_cpu(cpu_quiescent)++; + rcu_process_callbacks(0); +} + + +#ifdef CONFIG_SMP +static void rcu_percpu_tick(void) +{ + int cpu; + + for (cpu = 0; cpu < smp_num_cpus; cpu++) { + up(&per_cpu(rcu_sema, cpu)); + } +} +#else +static void rcu_percpu_tick(void) +{ + rcu_percpu_tick_common(); +} +#endif + +/* + * RCU timer handler - called one in every 50ms only if there is + * any RCU pending in the system. It nudges every CPU. + */ +static void rcu_timer_handler(unsigned long data) +{ + rcu_percpu_tick(); + spin_lock(&rcu_lock); + if (rcu_active_cpumask) { + rcu_timer.expires = jiffies + 5; + add_timer(&rcu_timer); + } + spin_unlock(&rcu_lock); + +} + +#ifdef CONFIG_SMP +/* + * Per-CPU RCU dameon. It runs at an absurdly high priority so + * that it is not starved out by the scheduler thereby holding + * up RC updates. + */ +static int krcud(void * __bind_cpu) +{ + int bind_cpu = *(int *) __bind_cpu; + int cpu = cpu_logical_map(bind_cpu); + + daemonize(); + current->policy = SCHED_FIFO; + current->rt_priority = 1001 + sys_sched_get_priority_max(SCHED_FIFO); + + sigfillset(¤t->blocked); + + /* Migrate to the right CPU */ + set_cpus_allowed(current, 1UL << cpu); + + sprintf(current->comm, "krcud_CPU%d", bind_cpu); + sema_init(&this_cpu(rcu_sema), 0); + + this_cpu(rcu_task) = current; + + for (;;) { + while (down_interruptible(&this_cpu(rcu_sema))); + local_bh_disable(); + rcu_percpu_tick_common(); + local_bh_enable(); + } +} + +static void spawn_krcud(void) +{ + int cpu; + + for (cpu = 0; cpu < smp_num_cpus; cpu++) { + if (kernel_thread(krcud, (void *) &cpu, + CLONE_FS | CLONE_FILES | CLONE_SIGNAL) < 0) + printk(KERN_ERR "spawn_krcud() failed for cpu %d\n", + cpu); + else { + while (!per_cpu(rcu_task, cpu)) { + schedule(); + } + } + } +} + +#endif + +/* + * Initializes rcu mechanism. Assumed to be called early. + * That is before local timer(SMP) or jiffie timer (uniproc) is setup. + * Note that cpu_quiescent and friends are implicitly + * initialized due to the choice of ``0'' for RCU_CTR_INVALID. + */ +static __init int rcu_init(void) +{ + int i; + + for (i = 0; i < NR_CPUS; i++) { + tasklet_init(&per_cpu(rcu_tasklet, i), + rcu_process_callbacks, 0UL); + INIT_LIST_HEAD(&per_cpu(rcu_nextlist, i)); + INIT_LIST_HEAD(&per_cpu(rcu_currlist, i)); + INIT_LIST_HEAD(&per_cpu(rcu_donelist, i)); + } + init_timer(&rcu_timer); + rcu_timer.function = rcu_timer_handler; +#ifdef CONFIG_SMP + spawn_krcud(); +#endif + return 0; +} + +/* Because of FASTCALL declaration of complete, we use this wrapper */ +static void wakeme_after_rcu(void *completion) +{ + complete(completion); +} + +/* + * Wait until all the CPUs have gone through a "quiescent" state. + */ +void synchronize_kernel(void) +{ + struct rcu_head rcu; + DECLARE_COMPLETION(completion); + + /* Will wake me after RCU finished */ + call_rcu(&rcu, wakeme_after_rcu, &completion); + + /* Wait for it */ + wait_for_completion(&completion); +} + +__initcall(rcu_init); + +EXPORT_SYMBOL(call_rcu); +EXPORT_SYMBOL(synchronize_kernel); diff -urN linux-2.5.8-base/kernel/sched.c linux-2.5.8-rcu/kernel/sched.c --- linux-2.5.8-base/kernel/sched.c Mon Apr 15 00:48:47 2002 +++ linux-2.5.8-rcu/kernel/sched.c Fri Apr 19 18:26:09 2002 @@ -17,11 +17,13 @@ #include #include #include +#include #include #include #include #include #include +#include /* * Priority of a process goes from 0 to 139. The 0-99 @@ -150,6 +152,7 @@ } ____cacheline_aligned; static struct runqueue runqueues[NR_CPUS] __cacheline_aligned; +long cpu_quiescent __per_cpu_data; #define cpu_rq(cpu) (runqueues + (cpu)) #define this_rq() cpu_rq(smp_processor_id()) @@ -157,6 +160,24 @@ #define cpu_curr(cpu) (cpu_rq(cpu)->curr) #define rt_task(p) ((p)->prio < MAX_RT_PRIO) +#ifdef CONFIG_PREEMPT +atomic_t rcu_preempt_cntr[2] __per_cpu_data; +atomic_t *curr_preempt_cntr __per_cpu_data; +atomic_t *next_preempt_cntr __per_cpu_data; +#endif + +#ifdef CONFIG_PREEMPT +static inline void rcu_init_preempt_cntr(int cpu) +{ + atomic_set(&per_cpu(rcu_preempt_cntr[0], cpu), 0); + atomic_set(&per_cpu(rcu_preempt_cntr[1], cpu), 0); + per_cpu(curr_preempt_cntr, cpu) = + &per_cpu(rcu_preempt_cntr[1], cpu); + per_cpu(next_preempt_cntr, cpu) = + &per_cpu(rcu_preempt_cntr[0], cpu); +} +#endif + static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags) { struct runqueue *rq; @@ -768,8 +789,11 @@ * if entering from preempt_schedule, off a kernel preemption, * go straight to picking the next task. */ - if (unlikely(preempt_get_count() & PREEMPT_ACTIVE)) + if (unlikely(preempt_get_count() & PREEMPT_ACTIVE)) { goto pick_next_task; + } else { + rcu_preempt_put(); + } switch (prev->state) { case TASK_INTERRUPTIBLE: @@ -812,6 +836,7 @@ switch_tasks: prefetch(next); clear_tsk_need_resched(prev); + per_cpu(cpu_quiescent, prev->thread_info->cpu)++; if (likely(prev != next)) { rq->nr_switches++; @@ -852,6 +877,7 @@ return; ti->preempt_count = PREEMPT_ACTIVE; + rcu_preempt_get(); schedule(); ti->preempt_count = 0; barrier(); @@ -1575,6 +1601,7 @@ spin_lock_init(&rq->lock); spin_lock_init(&rq->frozen); INIT_LIST_HEAD(&rq->migration_queue); + rcu_init_preempt_cntr(i); for (j = 0; j < 2; j++) { array = rq->arrays + j;