From c17ef45342cc033fdf7bdd5b28615e0090f8d2e7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 23 Jun 2009 17:12:47 -0700 Subject: rcu: Remove Classic RCU Remove Classic RCU, given that the combination of Tree RCU and the proposed Bloatwatch RCU do everything that Classic RCU can with fewer bugs. Tree RCU has been default in x86 builds for almost six months, and seems to be quite reliable, so there does not seem to be much justification for keeping the Classic RCU code and config complexity around anymore. Signed-off-by: Paul E. McKenney Cc: akpm@linux-foundation.org Cc: niv@us.ibm.com Cc: dvhltc@us.ibm.com Cc: dipankar@in.ibm.com Cc: dhowells@redhat.com Cc: lethal@linux-sh.org Cc: kernel@wantstofly.org Signed-off-by: Ingo Molnar --- kernel/Makefile | 1 - kernel/rcuclassic.c | 807 ---------------------------------------------------- 2 files changed, 808 deletions(-) delete mode 100644 kernel/rcuclassic.c (limited to 'kernel') diff --git a/kernel/Makefile b/kernel/Makefile index 0a32cb21ec97..d6042bcc9e99 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -80,7 +80,6 @@ obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o -obj-$(CONFIG_CLASSIC_RCU) += rcuclassic.o obj-$(CONFIG_TREE_RCU) += rcutree.o obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o diff --git a/kernel/rcuclassic.c b/kernel/rcuclassic.c deleted file mode 100644 index 0f2b0b311304..000000000000 --- a/kernel/rcuclassic.c +++ /dev/null @@ -1,807 +0,0 @@ -/* - * 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 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/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 - - * Documentation/RCU - * - */ -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#ifdef CONFIG_DEBUG_LOCK_ALLOC -static struct lock_class_key rcu_lock_key; -struct lockdep_map rcu_lock_map = - STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); -EXPORT_SYMBOL_GPL(rcu_lock_map); -#endif - - -/* Definition for rcupdate control block. */ -static struct rcu_ctrlblk rcu_ctrlblk = { - .cur = -300, - .completed = -300, - .pending = -300, - .lock = __SPIN_LOCK_UNLOCKED(&rcu_ctrlblk.lock), - .cpumask = CPU_BITS_NONE, -}; - -static struct rcu_ctrlblk rcu_bh_ctrlblk = { - .cur = -300, - .completed = -300, - .pending = -300, - .lock = __SPIN_LOCK_UNLOCKED(&rcu_bh_ctrlblk.lock), - .cpumask = CPU_BITS_NONE, -}; - -static DEFINE_PER_CPU(struct rcu_data, rcu_data); -static DEFINE_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. - */ -void rcu_qsctr_inc(int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - rdp->passed_quiesc = 1; -} - -void rcu_bh_qsctr_inc(int cpu) -{ - struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); - rdp->passed_quiesc = 1; -} - -static int blimit = 10; -static int qhimark = 10000; -static int qlowmark = 100; - -#ifdef CONFIG_SMP -static void force_quiescent_state(struct rcu_data *rdp, - struct rcu_ctrlblk *rcp) -{ - int cpu; - unsigned long flags; - - set_need_resched(); - spin_lock_irqsave(&rcp->lock, flags); - if (unlikely(!rcp->signaled)) { - rcp->signaled = 1; - /* - * Don't send IPI to itself. With irqs disabled, - * rdp->cpu is the current cpu. - * - * cpu_online_mask is updated by the _cpu_down() - * using __stop_machine(). Since we're in irqs disabled - * section, __stop_machine() is not exectuting, hence - * the cpu_online_mask is stable. - * - * However, a cpu might have been offlined _just_ before - * we disabled irqs while entering here. - * And rcu subsystem might not yet have handled the CPU_DEAD - * notification, leading to the offlined cpu's bit - * being set in the rcp->cpumask. - * - * Hence cpumask = (rcp->cpumask & cpu_online_mask) to prevent - * sending smp_reschedule() to an offlined CPU. - */ - for_each_cpu_and(cpu, - to_cpumask(rcp->cpumask), cpu_online_mask) { - if (cpu != rdp->cpu) - smp_send_reschedule(cpu); - } - } - spin_unlock_irqrestore(&rcp->lock, flags); -} -#else -static inline void force_quiescent_state(struct rcu_data *rdp, - struct rcu_ctrlblk *rcp) -{ - set_need_resched(); -} -#endif - -static void __call_rcu(struct rcu_head *head, struct rcu_ctrlblk *rcp, - struct rcu_data *rdp) -{ - long batch; - - head->next = NULL; - smp_mb(); /* Read of rcu->cur must happen after any change by caller. */ - - /* - * Determine the batch number of this callback. - * - * Using ACCESS_ONCE to avoid the following error when gcc eliminates - * local variable "batch" and emits codes like this: - * 1) rdp->batch = rcp->cur + 1 # gets old value - * ...... - * 2)rcu_batch_after(rcp->cur + 1, rdp->batch) # gets new value - * then [*nxttail[0], *nxttail[1]) may contain callbacks - * that batch# = rdp->batch, see the comment of struct rcu_data. - */ - batch = ACCESS_ONCE(rcp->cur) + 1; - - if (rdp->nxtlist && rcu_batch_after(batch, rdp->batch)) { - /* process callbacks */ - rdp->nxttail[0] = rdp->nxttail[1]; - rdp->nxttail[1] = rdp->nxttail[2]; - if (rcu_batch_after(batch - 1, rdp->batch)) - rdp->nxttail[0] = rdp->nxttail[2]; - } - - rdp->batch = batch; - *rdp->nxttail[2] = head; - rdp->nxttail[2] = &head->next; - - if (unlikely(++rdp->qlen > qhimark)) { - rdp->blimit = INT_MAX; - force_quiescent_state(rdp, &rcu_ctrlblk); - } -} - -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - -static void record_gp_stall_check_time(struct rcu_ctrlblk *rcp) -{ - rcp->gp_start = jiffies; - rcp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; -} - -static void print_other_cpu_stall(struct rcu_ctrlblk *rcp) -{ - int cpu; - long delta; - unsigned long flags; - - /* Only let one CPU complain about others per time interval. */ - - spin_lock_irqsave(&rcp->lock, flags); - delta = jiffies - rcp->jiffies_stall; - if (delta < 2 || rcp->cur != rcp->completed) { - spin_unlock_irqrestore(&rcp->lock, flags); - return; - } - rcp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; - spin_unlock_irqrestore(&rcp->lock, flags); - - /* OK, time to rat on our buddy... */ - - printk(KERN_ERR "INFO: RCU detected CPU stalls:"); - for_each_possible_cpu(cpu) { - if (cpumask_test_cpu(cpu, to_cpumask(rcp->cpumask))) - printk(" %d", cpu); - } - printk(" (detected by %d, t=%ld jiffies)\n", - smp_processor_id(), (long)(jiffies - rcp->gp_start)); -} - -static void print_cpu_stall(struct rcu_ctrlblk *rcp) -{ - unsigned long flags; - - printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu/%lu jiffies)\n", - smp_processor_id(), jiffies, - jiffies - rcp->gp_start); - dump_stack(); - spin_lock_irqsave(&rcp->lock, flags); - if ((long)(jiffies - rcp->jiffies_stall) >= 0) - rcp->jiffies_stall = - jiffies + RCU_SECONDS_TILL_STALL_RECHECK; - spin_unlock_irqrestore(&rcp->lock, flags); - set_need_resched(); /* kick ourselves to get things going. */ -} - -static void check_cpu_stall(struct rcu_ctrlblk *rcp) -{ - long delta; - - delta = jiffies - rcp->jiffies_stall; - if (cpumask_test_cpu(smp_processor_id(), to_cpumask(rcp->cpumask)) && - delta >= 0) { - - /* We haven't checked in, so go dump stack. */ - print_cpu_stall(rcp); - - } else if (rcp->cur != rcp->completed && delta >= 2) { - - /* They had two seconds to dump stack, so complain. */ - print_other_cpu_stall(rcp); - } -} - -#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - -static void record_gp_stall_check_time(struct rcu_ctrlblk *rcp) -{ -} - -static inline void check_cpu_stall(struct rcu_ctrlblk *rcp) -{ -} - -#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - -/** - * 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 call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *rcu)) -{ - unsigned long flags; - - head->func = func; - local_irq_save(flags); - __call_rcu(head, &rcu_ctrlblk, &__get_cpu_var(rcu_data)); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(call_rcu); - -/** - * 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 call_rcu_bh(struct rcu_head *head, - void (*func)(struct rcu_head *rcu)) -{ - unsigned long flags; - - head->func = func; - local_irq_save(flags); - __call_rcu(head, &rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(call_rcu_bh); - -/* - * Return the number of RCU batches processed thus far. Useful - * for debug and statistics. - */ -long rcu_batches_completed(void) -{ - return rcu_ctrlblk.completed; -} -EXPORT_SYMBOL_GPL(rcu_batches_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; -} -EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); - -/* Raises the softirq for processing rcu_callbacks. */ -static inline void raise_rcu_softirq(void) -{ - raise_softirq(RCU_SOFTIRQ); -} - -/* - * Invoke the completed RCU callbacks. They are expected to be in - * a per-cpu list. - */ -static void rcu_do_batch(struct rcu_data *rdp) -{ - unsigned long flags; - struct rcu_head *next, *list; - int count = 0; - - list = rdp->donelist; - while (list) { - next = list->next; - prefetch(next); - list->func(list); - list = next; - if (++count >= rdp->blimit) - break; - } - rdp->donelist = list; - - local_irq_save(flags); - rdp->qlen -= count; - local_irq_restore(flags); - if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark) - rdp->blimit = blimit; - - if (!rdp->donelist) - rdp->donetail = &rdp->donelist; - else - raise_rcu_softirq(); -} - -/* - * 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->cur != rcp->pending && - rcp->completed == rcp->cur) { - rcp->cur++; - record_gp_stall_check_time(rcp); - - /* - * 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(); - cpumask_andnot(to_cpumask(rcp->cpumask), - cpu_online_mask, nohz_cpu_mask); - - rcp->signaled = 0; - } -} - -/* - * 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) -{ - cpumask_clear_cpu(cpu, to_cpumask(rcp->cpumask)); - if (cpumask_empty(to_cpumask(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) -{ - unsigned long flags; - - 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_irqsave(&rcp->lock, flags); - /* - * 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_irqrestore(&rcp->lock, flags); -} - - -#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, long batch) -{ - unsigned long flags; - - if (list) { - local_irq_save(flags); - this_rdp->batch = batch; - *this_rdp->nxttail[2] = list; - this_rdp->nxttail[2] = tail; - local_irq_restore(flags); - } -} - -static void __rcu_offline_cpu(struct rcu_data *this_rdp, - struct rcu_ctrlblk *rcp, struct rcu_data *rdp) -{ - unsigned long flags; - - /* - * if the cpu going offline owns the grace period - * we can block indefinitely waiting for it, so flush - * it here - */ - spin_lock_irqsave(&rcp->lock, flags); - if (rcp->cur != rcp->completed) - cpu_quiet(rdp->cpu, rcp); - rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail, rcp->cur + 1); - rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail[2], rcp->cur + 1); - spin_unlock(&rcp->lock); - - this_rdp->qlen += rdp->qlen; - local_irq_restore(flags); -} - -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); -} - -#else - -static void rcu_offline_cpu(int cpu) -{ -} - -#endif - -/* - * This does the RCU processing work from softirq context. - */ -static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, - struct rcu_data *rdp) -{ - unsigned long flags; - long completed_snap; - - if (rdp->nxtlist) { - local_irq_save(flags); - completed_snap = ACCESS_ONCE(rcp->completed); - - /* - * move the other grace-period-completed entries to - * [rdp->nxtlist, *rdp->nxttail[0]) temporarily - */ - if (!rcu_batch_before(completed_snap, rdp->batch)) - rdp->nxttail[0] = rdp->nxttail[1] = rdp->nxttail[2]; - else if (!rcu_batch_before(completed_snap, rdp->batch - 1)) - rdp->nxttail[0] = rdp->nxttail[1]; - - /* - * the grace period for entries in - * [rdp->nxtlist, *rdp->nxttail[0]) has completed and - * move these entries to donelist - */ - if (rdp->nxttail[0] != &rdp->nxtlist) { - *rdp->donetail = rdp->nxtlist; - rdp->donetail = rdp->nxttail[0]; - rdp->nxtlist = *rdp->nxttail[0]; - *rdp->donetail = NULL; - - if (rdp->nxttail[1] == rdp->nxttail[0]) - rdp->nxttail[1] = &rdp->nxtlist; - if (rdp->nxttail[2] == rdp->nxttail[0]) - rdp->nxttail[2] = &rdp->nxtlist; - rdp->nxttail[0] = &rdp->nxtlist; - } - - local_irq_restore(flags); - - if (rcu_batch_after(rdp->batch, rcp->pending)) { - unsigned long flags2; - - /* and start it/schedule start if it's a new batch */ - spin_lock_irqsave(&rcp->lock, flags2); - if (rcu_batch_after(rdp->batch, rcp->pending)) { - rcp->pending = rdp->batch; - rcu_start_batch(rcp); - } - spin_unlock_irqrestore(&rcp->lock, flags2); - } - } - - rcu_check_quiescent_state(rcp, rdp); - if (rdp->donelist) - rcu_do_batch(rdp); -} - -static void rcu_process_callbacks(struct softirq_action *unused) -{ - /* - * Memory references from any prior RCU read-side critical sections - * executed by the interrupted code must be see before any RCU - * grace-period manupulations below. - */ - - smp_mb(); /* See above block comment. */ - - __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data)); - __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); - - /* - * Memory references from any later RCU read-side critical sections - * executed by the interrupted code must be see after any RCU - * grace-period manupulations above. - */ - - smp_mb(); /* See above block comment. */ -} - -static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp) -{ - /* Check for CPU stalls, if enabled. */ - check_cpu_stall(rcp); - - if (rdp->nxtlist) { - long completed_snap = ACCESS_ONCE(rcp->completed); - - /* - * This cpu has pending rcu entries and the grace period - * for them has completed. - */ - if (!rcu_batch_before(completed_snap, rdp->batch)) - return 1; - if (!rcu_batch_before(completed_snap, rdp->batch - 1) && - rdp->nxttail[0] != rdp->nxttail[1]) - return 1; - if (rdp->nxttail[0] != &rdp->nxtlist) - return 1; - - /* - * This cpu has pending rcu entries and the new batch - * for then hasn't been started nor scheduled start - */ - if (rcu_batch_after(rdp->batch, rcp->pending)) - 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->nxtlist || !!rdp_bh->nxtlist || rcu_pending(cpu); -} - -/* - * Top-level function driving RCU grace-period detection, normally - * invoked from the scheduler-clock interrupt. This function simply - * increments counters that are read only from softirq by this same - * CPU, so there are no memory barriers required. - */ -void rcu_check_callbacks(int cpu, int user) -{ - if (user || - (idle_cpu(cpu) && rcu_scheduler_active && - !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { - - /* - * Get here if this CPU took its interrupt from user - * mode or from the idle loop, and if this is not a - * nested interrupt. In this case, the CPU is in - * a quiescent state, so count it. - * - * Also do a memory barrier. This is needed to handle - * the case where writes from a preempt-disable section - * of code get reordered into schedule() by this CPU's - * write buffer. The memory barrier makes sure that - * the rcu_qsctr_inc() and rcu_bh_qsctr_inc() are see - * by other CPUs to happen after any such write. - */ - - smp_mb(); /* See above block comment. */ - rcu_qsctr_inc(cpu); - rcu_bh_qsctr_inc(cpu); - - } else if (!in_softirq()) { - - /* - * Get here if this CPU did not take its interrupt from - * softirq, in other words, if it is not interrupting - * a rcu_bh read-side critical section. This is an _bh - * critical section, so count it. The memory barrier - * is needed for the same reason as is the above one. - */ - - smp_mb(); /* See above block comment. */ - rcu_bh_qsctr_inc(cpu); - } - raise_rcu_softirq(); -} - -static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp, - struct rcu_data *rdp) -{ - unsigned long flags; - - spin_lock_irqsave(&rcp->lock, flags); - memset(rdp, 0, sizeof(*rdp)); - rdp->nxttail[0] = rdp->nxttail[1] = rdp->nxttail[2] = &rdp->nxtlist; - rdp->donetail = &rdp->donelist; - rdp->quiescbatch = rcp->completed; - rdp->qs_pending = 0; - rdp->cpu = cpu; - rdp->blimit = blimit; - spin_unlock_irqrestore(&rcp->lock, flags); -} - -static void __cpuinit 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); - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); -} - -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: - case CPU_UP_PREPARE_FROZEN: - rcu_online_cpu(cpu); - break; - case CPU_DEAD: - case CPU_DEAD_FROZEN: - 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) -{ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - 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); -- cgit v1.2.3 From 03b042bf1dc14a268a3d65d38b4ec2a4261e8477 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 25 Jun 2009 09:08:16 -0700 Subject: rcu: Add synchronize_sched_expedited() primitive This adds the synchronize_sched_expedited() primitive that implements the "big hammer" expedited RCU grace periods. This primitive is placed in kernel/sched.c rather than kernel/rcupdate.c due to its need to interact closely with the migration_thread() kthread. The idea is to wake up this kthread with req->task set to NULL, in response to which the kthread reports the quiescent state resulting from the kthread having been scheduled. Because this patch needs to fallback to the slow versions of the primitives in response to some races with CPU onlining and offlining, a new synchronize_rcu_bh() primitive is added as well. Signed-off-by: Paul E. McKenney Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Cc: davem@davemloft.net Cc: dada1@cosmosbay.com Cc: zbr@ioremap.net Cc: jeff.chua.linux@gmail.com Cc: paulus@samba.org Cc: laijs@cn.fujitsu.com Cc: jengelh@medozas.de Cc: r000n@r000n.net Cc: benh@kernel.crashing.org Cc: mathieu.desnoyers@polymtl.ca LKML-Reference: <12459460982947-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcupdate.c | 25 +++++++++++ kernel/sched.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 152 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index a967c9feb90a..eae29c25fb14 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -98,6 +98,30 @@ void synchronize_rcu(void) } EXPORT_SYMBOL_GPL(synchronize_rcu); +/** + * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. + * + * Control will return to the caller some time after a full rcu_bh grace + * period has elapsed, in other words after all currently executing rcu_bh + * read-side critical sections have completed. RCU read-side critical + * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), + * and may be nested. + */ +void synchronize_rcu_bh(void) +{ + struct rcu_synchronize rcu; + + if (rcu_blocking_is_gp()) + return; + + 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(synchronize_rcu_bh); + static void rcu_barrier_callback(struct rcu_head *notused) { if (atomic_dec_and_test(&rcu_barrier_cpu_count)) @@ -129,6 +153,7 @@ static void rcu_barrier_func(void *type) static inline void wait_migrated_callbacks(void) { wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count)); + smp_mb(); /* In case we didn't sleep. */ } /* diff --git a/kernel/sched.c b/kernel/sched.c index 7c9098d186e6..9ae80bec1c1e 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7024,6 +7024,11 @@ fail: return ret; } +#define RCU_MIGRATION_IDLE 0 +#define RCU_MIGRATION_NEED_QS 1 +#define RCU_MIGRATION_GOT_QS 2 +#define RCU_MIGRATION_MUST_SYNC 3 + /* * migration_thread - this is a highprio system thread that performs * thread migration by bumping thread off CPU then 'pushing' onto @@ -7031,6 +7036,7 @@ fail: */ static int migration_thread(void *data) { + int badcpu; int cpu = (long)data; struct rq *rq; @@ -7065,8 +7071,17 @@ static int migration_thread(void *data) req = list_entry(head->next, struct migration_req, list); list_del_init(head->next); - spin_unlock(&rq->lock); - __migrate_task(req->task, cpu, req->dest_cpu); + if (req->task != NULL) { + spin_unlock(&rq->lock); + __migrate_task(req->task, cpu, req->dest_cpu); + } else if (likely(cpu == (badcpu = smp_processor_id()))) { + req->dest_cpu = RCU_MIGRATION_GOT_QS; + spin_unlock(&rq->lock); + } else { + req->dest_cpu = RCU_MIGRATION_MUST_SYNC; + spin_unlock(&rq->lock); + WARN_ONCE(1, "migration_thread() on CPU %d, expected %d\n", badcpu, cpu); + } local_irq_enable(); complete(&req->done); @@ -10554,3 +10569,113 @@ struct cgroup_subsys cpuacct_subsys = { .subsys_id = cpuacct_subsys_id, }; #endif /* CONFIG_CGROUP_CPUACCT */ + +#ifndef CONFIG_SMP + +int rcu_expedited_torture_stats(char *page) +{ + return 0; +} +EXPORT_SYMBOL_GPL(rcu_expedited_torture_stats); + +void synchronize_sched_expedited(void) +{ +} +EXPORT_SYMBOL_GPL(synchronize_sched_expedited); + +#else /* #ifndef CONFIG_SMP */ + +static DEFINE_PER_CPU(struct migration_req, rcu_migration_req); +static DEFINE_MUTEX(rcu_sched_expedited_mutex); + +#define RCU_EXPEDITED_STATE_POST -2 +#define RCU_EXPEDITED_STATE_IDLE -1 + +static int rcu_expedited_state = RCU_EXPEDITED_STATE_IDLE; + +int rcu_expedited_torture_stats(char *page) +{ + int cnt = 0; + int cpu; + + cnt += sprintf(&page[cnt], "state: %d /", rcu_expedited_state); + for_each_online_cpu(cpu) { + cnt += sprintf(&page[cnt], " %d:%d", + cpu, per_cpu(rcu_migration_req, cpu).dest_cpu); + } + cnt += sprintf(&page[cnt], "\n"); + return cnt; +} +EXPORT_SYMBOL_GPL(rcu_expedited_torture_stats); + +static long synchronize_sched_expedited_count; + +/* + * Wait for an rcu-sched grace period to elapse, but use "big hammer" + * approach to force grace period to end quickly. This consumes + * significant time on all CPUs, and is thus not recommended for + * any sort of common-case code. + * + * Note that it is illegal to call this function while holding any + * lock that is acquired by a CPU-hotplug notifier. Failing to + * observe this restriction will result in deadlock. + */ +void synchronize_sched_expedited(void) +{ + int cpu; + unsigned long flags; + bool need_full_sync = 0; + struct rq *rq; + struct migration_req *req; + long snap; + int trycount = 0; + + smp_mb(); /* ensure prior mod happens before capturing snap. */ + snap = ACCESS_ONCE(synchronize_sched_expedited_count) + 1; + get_online_cpus(); + while (!mutex_trylock(&rcu_sched_expedited_mutex)) { + put_online_cpus(); + if (trycount++ < 10) + udelay(trycount * num_online_cpus()); + else { + synchronize_sched(); + return; + } + if (ACCESS_ONCE(synchronize_sched_expedited_count) - snap > 0) { + smp_mb(); /* ensure test happens before caller kfree */ + return; + } + get_online_cpus(); + } + rcu_expedited_state = RCU_EXPEDITED_STATE_POST; + for_each_online_cpu(cpu) { + rq = cpu_rq(cpu); + req = &per_cpu(rcu_migration_req, cpu); + init_completion(&req->done); + req->task = NULL; + req->dest_cpu = RCU_MIGRATION_NEED_QS; + spin_lock_irqsave(&rq->lock, flags); + list_add(&req->list, &rq->migration_queue); + spin_unlock_irqrestore(&rq->lock, flags); + wake_up_process(rq->migration_thread); + } + for_each_online_cpu(cpu) { + rcu_expedited_state = cpu; + req = &per_cpu(rcu_migration_req, cpu); + rq = cpu_rq(cpu); + wait_for_completion(&req->done); + spin_lock_irqsave(&rq->lock, flags); + if (unlikely(req->dest_cpu == RCU_MIGRATION_MUST_SYNC)) + need_full_sync = 1; + req->dest_cpu = RCU_MIGRATION_IDLE; + spin_unlock_irqrestore(&rq->lock, flags); + } + rcu_expedited_state = RCU_EXPEDITED_STATE_IDLE; + mutex_unlock(&rcu_sched_expedited_mutex); + put_online_cpus(); + if (need_full_sync) + synchronize_sched(); +} +EXPORT_SYMBOL_GPL(synchronize_sched_expedited); + +#endif /* #else #ifndef CONFIG_SMP */ -- cgit v1.2.3 From 0acc512cb1a29636df5e982c7d845edafe77c2d0 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 25 Jun 2009 09:08:17 -0700 Subject: rcu: Add synchronize_sched_expedited() torture tests This patch adds rcutorture tests for the new synchronize_sched_expedited() primitive, and also does some whitespace cleanups in kernel/rcutorture.c as well. Signed-off-by: Paul E. McKenney Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Cc: davem@davemloft.net Cc: dada1@cosmosbay.com Cc: zbr@ioremap.net Cc: jeff.chua.linux@gmail.com Cc: paulus@samba.org Cc: laijs@cn.fujitsu.com Cc: jengelh@medozas.de Cc: r000n@r000n.net Cc: benh@kernel.crashing.org Cc: mathieu.desnoyers@polymtl.ca LKML-Reference: <12459460981342-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutorture.c | 202 ++++++++++++++++++++++++++++------------------------ 1 file changed, 110 insertions(+), 92 deletions(-) (limited to 'kernel') diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 9b4a975a4b4a..b33db539a8ad 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -257,14 +257,14 @@ struct rcu_torture_ops { void (*init)(void); void (*cleanup)(void); int (*readlock)(void); - void (*readdelay)(struct rcu_random_state *rrsp); + void (*read_delay)(struct rcu_random_state *rrsp); void (*readunlock)(int idx); int (*completed)(void); - void (*deferredfree)(struct rcu_torture *p); + void (*deferred_free)(struct rcu_torture *p); void (*sync)(void); void (*cb_barrier)(void); int (*stats)(char *page); - int irqcapable; + int irq_capable; char *name; }; static struct rcu_torture_ops *cur_ops = NULL; @@ -320,7 +320,7 @@ rcu_torture_cb(struct rcu_head *p) rp->rtort_mbtest = 0; rcu_torture_free(rp); } else - cur_ops->deferredfree(rp); + cur_ops->deferred_free(rp); } static void rcu_torture_deferred_free(struct rcu_torture *p) @@ -329,18 +329,18 @@ static void rcu_torture_deferred_free(struct rcu_torture *p) } static struct rcu_torture_ops rcu_ops = { - .init = NULL, - .cleanup = NULL, - .readlock = rcu_torture_read_lock, - .readdelay = rcu_read_delay, - .readunlock = rcu_torture_read_unlock, - .completed = rcu_torture_completed, - .deferredfree = rcu_torture_deferred_free, - .sync = synchronize_rcu, - .cb_barrier = rcu_barrier, - .stats = NULL, - .irqcapable = 1, - .name = "rcu" + .init = NULL, + .cleanup = NULL, + .readlock = rcu_torture_read_lock, + .read_delay = rcu_read_delay, + .readunlock = rcu_torture_read_unlock, + .completed = rcu_torture_completed, + .deferred_free = rcu_torture_deferred_free, + .sync = synchronize_rcu, + .cb_barrier = rcu_barrier, + .stats = NULL, + .irq_capable = 1, + .name = "rcu" }; static void rcu_sync_torture_deferred_free(struct rcu_torture *p) @@ -370,18 +370,18 @@ static void rcu_sync_torture_init(void) } static struct rcu_torture_ops rcu_sync_ops = { - .init = rcu_sync_torture_init, - .cleanup = NULL, - .readlock = rcu_torture_read_lock, - .readdelay = rcu_read_delay, - .readunlock = rcu_torture_read_unlock, - .completed = rcu_torture_completed, - .deferredfree = rcu_sync_torture_deferred_free, - .sync = synchronize_rcu, - .cb_barrier = NULL, - .stats = NULL, - .irqcapable = 1, - .name = "rcu_sync" + .init = rcu_sync_torture_init, + .cleanup = NULL, + .readlock = rcu_torture_read_lock, + .read_delay = rcu_read_delay, + .readunlock = rcu_torture_read_unlock, + .completed = rcu_torture_completed, + .deferred_free = rcu_sync_torture_deferred_free, + .sync = synchronize_rcu, + .cb_barrier = NULL, + .stats = NULL, + .irq_capable = 1, + .name = "rcu_sync" }; /* @@ -432,33 +432,33 @@ static void rcu_bh_torture_synchronize(void) } static struct rcu_torture_ops rcu_bh_ops = { - .init = NULL, - .cleanup = NULL, - .readlock = rcu_bh_torture_read_lock, - .readdelay = rcu_read_delay, /* just reuse rcu's version. */ - .readunlock = rcu_bh_torture_read_unlock, - .completed = rcu_bh_torture_completed, - .deferredfree = rcu_bh_torture_deferred_free, - .sync = rcu_bh_torture_synchronize, - .cb_barrier = rcu_barrier_bh, - .stats = NULL, - .irqcapable = 1, - .name = "rcu_bh" + .init = NULL, + .cleanup = NULL, + .readlock = rcu_bh_torture_read_lock, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = rcu_bh_torture_read_unlock, + .completed = rcu_bh_torture_completed, + .deferred_free = rcu_bh_torture_deferred_free, + .sync = rcu_bh_torture_synchronize, + .cb_barrier = rcu_barrier_bh, + .stats = NULL, + .irq_capable = 1, + .name = "rcu_bh" }; static struct rcu_torture_ops rcu_bh_sync_ops = { - .init = rcu_sync_torture_init, - .cleanup = NULL, - .readlock = rcu_bh_torture_read_lock, - .readdelay = rcu_read_delay, /* just reuse rcu's version. */ - .readunlock = rcu_bh_torture_read_unlock, - .completed = rcu_bh_torture_completed, - .deferredfree = rcu_sync_torture_deferred_free, - .sync = rcu_bh_torture_synchronize, - .cb_barrier = NULL, - .stats = NULL, - .irqcapable = 1, - .name = "rcu_bh_sync" + .init = rcu_sync_torture_init, + .cleanup = NULL, + .readlock = rcu_bh_torture_read_lock, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = rcu_bh_torture_read_unlock, + .completed = rcu_bh_torture_completed, + .deferred_free = rcu_sync_torture_deferred_free, + .sync = rcu_bh_torture_synchronize, + .cb_barrier = NULL, + .stats = NULL, + .irq_capable = 1, + .name = "rcu_bh_sync" }; /* @@ -530,17 +530,17 @@ static int srcu_torture_stats(char *page) } static struct rcu_torture_ops srcu_ops = { - .init = srcu_torture_init, - .cleanup = srcu_torture_cleanup, - .readlock = srcu_torture_read_lock, - .readdelay = srcu_read_delay, - .readunlock = srcu_torture_read_unlock, - .completed = srcu_torture_completed, - .deferredfree = rcu_sync_torture_deferred_free, - .sync = srcu_torture_synchronize, - .cb_barrier = NULL, - .stats = srcu_torture_stats, - .name = "srcu" + .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, + .cb_barrier = NULL, + .stats = srcu_torture_stats, + .name = "srcu" }; /* @@ -574,32 +574,49 @@ static void sched_torture_synchronize(void) } static struct rcu_torture_ops sched_ops = { - .init = rcu_sync_torture_init, - .cleanup = NULL, - .readlock = sched_torture_read_lock, - .readdelay = rcu_read_delay, /* just reuse rcu's version. */ - .readunlock = sched_torture_read_unlock, - .completed = sched_torture_completed, - .deferredfree = rcu_sched_torture_deferred_free, - .sync = sched_torture_synchronize, - .cb_barrier = rcu_barrier_sched, - .stats = NULL, - .irqcapable = 1, - .name = "sched" + .init = rcu_sync_torture_init, + .cleanup = NULL, + .readlock = sched_torture_read_lock, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = sched_torture_read_unlock, + .completed = sched_torture_completed, + .deferred_free = rcu_sched_torture_deferred_free, + .sync = sched_torture_synchronize, + .cb_barrier = rcu_barrier_sched, + .stats = NULL, + .irq_capable = 1, + .name = "sched" }; static struct rcu_torture_ops sched_ops_sync = { - .init = rcu_sync_torture_init, - .cleanup = NULL, - .readlock = sched_torture_read_lock, - .readdelay = rcu_read_delay, /* just reuse rcu's version. */ - .readunlock = sched_torture_read_unlock, - .completed = sched_torture_completed, - .deferredfree = rcu_sync_torture_deferred_free, - .sync = sched_torture_synchronize, - .cb_barrier = NULL, - .stats = NULL, - .name = "sched_sync" + .init = rcu_sync_torture_init, + .cleanup = NULL, + .readlock = sched_torture_read_lock, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = sched_torture_read_unlock, + .completed = sched_torture_completed, + .deferred_free = rcu_sync_torture_deferred_free, + .sync = sched_torture_synchronize, + .cb_barrier = NULL, + .stats = NULL, + .name = "sched_sync" +}; + +extern int rcu_expedited_torture_stats(char *page); + +static struct rcu_torture_ops sched_expedited_ops = { + .init = rcu_sync_torture_init, + .cleanup = NULL, + .readlock = sched_torture_read_lock, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = sched_torture_read_unlock, + .completed = sched_torture_completed, + .deferred_free = rcu_sync_torture_deferred_free, + .sync = synchronize_sched_expedited, + .cb_barrier = NULL, + .stats = rcu_expedited_torture_stats, + .irq_capable = 1, + .name = "sched_expedited" }; /* @@ -635,7 +652,7 @@ rcu_torture_writer(void *arg) i = RCU_TORTURE_PIPE_LEN; atomic_inc(&rcu_torture_wcount[i]); old_rp->rtort_pipe_count++; - cur_ops->deferredfree(old_rp); + cur_ops->deferred_free(old_rp); } rcu_torture_current_version++; oldbatch = cur_ops->completed(); @@ -700,7 +717,7 @@ static void rcu_torture_timer(unsigned long unused) if (p->rtort_mbtest == 0) atomic_inc(&n_rcu_torture_mberror); spin_lock(&rand_lock); - cur_ops->readdelay(&rand); + cur_ops->read_delay(&rand); n_rcu_torture_timers++; spin_unlock(&rand_lock); preempt_disable(); @@ -738,11 +755,11 @@ rcu_torture_reader(void *arg) VERBOSE_PRINTK_STRING("rcu_torture_reader task started"); set_user_nice(current, 19); - if (irqreader && cur_ops->irqcapable) + if (irqreader && cur_ops->irq_capable) setup_timer_on_stack(&t, rcu_torture_timer, 0); do { - if (irqreader && cur_ops->irqcapable) { + if (irqreader && cur_ops->irq_capable) { if (!timer_pending(&t)) mod_timer(&t, 1); } @@ -757,7 +774,7 @@ rcu_torture_reader(void *arg) } if (p->rtort_mbtest == 0) atomic_inc(&n_rcu_torture_mberror); - cur_ops->readdelay(&rand); + cur_ops->read_delay(&rand); preempt_disable(); pipe_count = p->rtort_pipe_count; if (pipe_count > RCU_TORTURE_PIPE_LEN) { @@ -778,7 +795,7 @@ rcu_torture_reader(void *arg) } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP); VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping"); rcutorture_shutdown_absorb("rcu_torture_reader"); - if (irqreader && cur_ops->irqcapable) + if (irqreader && cur_ops->irq_capable) del_timer_sync(&t); while (!kthread_should_stop()) schedule_timeout_uninterruptible(1); @@ -1078,6 +1095,7 @@ 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, }; mutex_lock(&fullstop_mutex); -- cgit v1.2.3 From 27569620c748ec13f801b4683b448a2ac2adaae4 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 15 Aug 2009 09:53:46 -0700 Subject: rcu: Split hierarchical RCU initialization into boot-time and CPU-online pieces This patch divides the rcutree initialization into boot-time and hotplug-time components, so that the tree data structures are guaranteed to be fully linked at boot time regardless of what might happen in CPU hotplug operations. This makes RCU more resilient against CPU hotplug misbehavior (and vice versa), but more importantly, does a better job of compartmentalizing the code. Reported-by: Ingo Molnar Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: josht@linux.vnet.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: hugh.dickins@tiscali.co.uk Cc: benh@kernel.crashing.org LKML-Reference: <1250355231152-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutree.c | 53 +++++++++++++++++++++++++++++++++-------------------- 1 file changed, 33 insertions(+), 20 deletions(-) (limited to 'kernel') diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 7717b95c2027..f3e43274ed53 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1325,22 +1325,40 @@ int rcu_needs_cpu(int cpu) } /* - * Initialize a CPU's per-CPU RCU data. We take this "scorched earth" - * approach so that we don't have to worry about how long the CPU has - * been gone, or whether it ever was online previously. We do trust the - * ->mynode field, as it is constant for a given struct rcu_data and - * initialized during early boot. - * - * Note that only one online or offline event can be happening at a given - * time. Note also that we can accept some slop in the rsp->completed - * access due to the fact that this CPU cannot possibly have any RCU - * callbacks in flight yet. + * Do boot-time initialization of a CPU's per-CPU RCU data. + */ +static void __init +rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) +{ + unsigned long flags; + int i; + struct rcu_data *rdp = rsp->rda[cpu]; + struct rcu_node *rnp = rcu_get_root(rsp); + + /* Set up local state, ensuring consistent view of global state. */ + spin_lock_irqsave(&rnp->lock, flags); + rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); + rdp->nxtlist = NULL; + for (i = 0; i < RCU_NEXT_SIZE; i++) + rdp->nxttail[i] = &rdp->nxtlist; + rdp->qlen = 0; +#ifdef CONFIG_NO_HZ + rdp->dynticks = &per_cpu(rcu_dynticks, cpu); +#endif /* #ifdef CONFIG_NO_HZ */ + rdp->cpu = cpu; + spin_unlock_irqrestore(&rnp->lock, flags); +} + +/* + * Initialize a CPU's per-CPU RCU data. Note that only one online or + * offline event can be happening at a given time. Note also that we + * can accept some slop in the rsp->completed access due to the fact + * that this CPU cannot possibly have any RCU callbacks in flight yet. */ static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp) { unsigned long flags; - int i; long lastcomp; unsigned long mask; struct rcu_data *rdp = rsp->rda[cpu]; @@ -1355,16 +1373,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp) rdp->qs_pending = 1; /* so set up to respond to current GP. */ rdp->beenonline = 1; /* We have now been online. */ rdp->passed_quiesc_completed = lastcomp - 1; - rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); - rdp->nxtlist = NULL; - for (i = 0; i < RCU_NEXT_SIZE; i++) - rdp->nxttail[i] = &rdp->nxtlist; - rdp->qlen = 0; rdp->blimit = blimit; -#ifdef CONFIG_NO_HZ - rdp->dynticks = &per_cpu(rcu_dynticks, cpu); -#endif /* #ifdef CONFIG_NO_HZ */ - rdp->cpu = cpu; spin_unlock(&rnp->lock); /* irqs remain disabled. */ /* @@ -1539,8 +1548,12 @@ void __init __rcu_init(void) #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ rcu_init_one(&rcu_state); RCU_DATA_PTR_INIT(&rcu_state, rcu_data); + for_each_possible_cpu(i) + rcu_boot_init_percpu_data(i, &rcu_state); rcu_init_one(&rcu_bh_state); RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data); + for_each_possible_cpu(i) + rcu_boot_init_percpu_data(i, &rcu_bh_state); for_each_online_cpu(i) rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long)i); -- cgit v1.2.3 From 2e597558086dec36d5c33521a36e0f6b1bc3f3a7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 15 Aug 2009 09:53:48 -0700 Subject: rcu: Simplify RCU CPU-hotplug notification Use the new cpu_notifier() API to simplify RCU's CPU-hotplug notifiers, collapsing down to a single such notifier. This makes it trivial to provide the notifier-ordering guarantee that rcu_barrier() depends on. Also remove redundant open_softirq() calls from Hierarchical RCU notifier. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: josht@linux.vnet.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: hugh.dickins@tiscali.co.uk Cc: benh@kernel.crashing.org LKML-Reference: <12503552312510-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcupdate.c | 16 +++++++++++++++- kernel/rcupreempt.c | 25 ++----------------------- kernel/rcutree.c | 17 +++++------------ 3 files changed, 22 insertions(+), 36 deletions(-) (limited to 'kernel') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index eae29c25fb14..8df115600c2d 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -217,9 +217,13 @@ static void rcu_migrate_callback(struct rcu_head *notused) wake_up(&rcu_migrate_wq); } +extern int rcu_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu); + static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self, unsigned long action, void *hcpu) { + rcu_cpu_notify(self, action, hcpu); if (action == CPU_DYING) { /* * preempt_disable() in on_each_cpu() prevents stop_machine(), @@ -244,8 +248,18 @@ static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self, void __init rcu_init(void) { + int i; + __rcu_init(); - hotcpu_notifier(rcu_barrier_cpu_hotplug, 0); + cpu_notifier(rcu_barrier_cpu_hotplug, 0); + + /* + * We don't need protection against CPU-hotplug here because + * this is called early in boot, before either interrupts + * or the scheduler are operational. + */ + for_each_online_cpu(i) + rcu_barrier_cpu_hotplug(NULL, CPU_UP_PREPARE, (void *)(long)i); } void rcu_scheduler_starting(void) diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c index beb0e659adcc..9b87f5134ed7 100644 --- a/kernel/rcupreempt.c +++ b/kernel/rcupreempt.c @@ -1417,8 +1417,8 @@ int rcu_pending(int cpu) return 0; } -static int __cpuinit rcu_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu) +int __cpuinit rcu_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) { long cpu = (long)hcpu; @@ -1439,10 +1439,6 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, return NOTIFY_OK; } -static struct notifier_block __cpuinitdata rcu_nb = { - .notifier_call = rcu_cpu_notify, -}; - void __init __rcu_init(void) { int cpu; @@ -1471,23 +1467,6 @@ void __init __rcu_init(void) rdp->waitschedtail = &rdp->waitschedlist; rdp->rcu_sched_sleeping = 0; } - register_cpu_notifier(&rcu_nb); - - /* - * We don't need protection against CPU-Hotplug here - * since - * a) If a CPU comes online while we are iterating over the - * cpu_online_mask below, we would only end up making a - * duplicate call to rcu_online_cpu() which sets the corresponding - * CPU's mask in the rcu_cpu_online_map. - * - * b) A CPU cannot go offline at this point in time since the user - * does not have access to the sysfs interface, nor do we - * suspend the system. - */ - for_each_online_cpu(cpu) - rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long) cpu); - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); } diff --git a/kernel/rcutree.c b/kernel/rcutree.c index f3e43274ed53..75762cddbe03 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1132,6 +1132,8 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) { unsigned long flags; + WARN_ON_ONCE(rdp->beenonline == 0); + /* * If an RCU GP has gone long enough, go check for dyntick * idle CPUs and, if needed, send resched IPIs. @@ -1416,14 +1418,13 @@ static void __cpuinit rcu_online_cpu(int cpu) { rcu_init_percpu_data(cpu, &rcu_state); rcu_init_percpu_data(cpu, &rcu_bh_state); - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); } /* * Handle CPU online/offline notifcation events. */ -static int __cpuinit rcu_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu) +int __cpuinit rcu_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) { long cpu = (long)hcpu; @@ -1532,10 +1533,6 @@ do { \ } \ } while (0) -static struct notifier_block __cpuinitdata rcu_nb = { - .notifier_call = rcu_cpu_notify, -}; - void __init __rcu_init(void) { int i; /* All used by RCU_DATA_PTR_INIT(). */ @@ -1554,11 +1551,7 @@ void __init __rcu_init(void) RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data); for_each_possible_cpu(i) rcu_boot_init_percpu_data(i, &rcu_bh_state); - - for_each_online_cpu(i) - rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long)i); - /* Register notifier for non-boot CPUs */ - register_cpu_notifier(&rcu_nb); + open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); } module_param(blimit, int, 0); -- cgit v1.2.3 From 8064d54929f23613e649dc7e14f7a94454487d58 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 15 Aug 2009 09:53:49 -0700 Subject: rcu: Make preemptable RCU scan all CPUs when summing RCU counters This patch eliminates the counter-moving during CPU-offline notifiers, eliminating potential confusion if counters are scanned during counter-movement process. This confusion could result in premature ending of an RCU grace period. For example, if there are two tasks in RCU read-side critical sections (so that the sum of the counters is two), and the counter for the CPU going offline is -2, then moving the count to another CPU can result in the sum momentarily appearing to be zero. Since there are no memory barriers in either case, many more such scenarios are possible. So just don't move the counts!!! Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: josht@linux.vnet.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: hugh.dickins@tiscali.co.uk Cc: benh@kernel.crashing.org LKML-Reference: <12503552312863-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcupreempt.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c index 9b87f5134ed7..2748b89910b6 100644 --- a/kernel/rcupreempt.c +++ b/kernel/rcupreempt.c @@ -849,7 +849,7 @@ rcu_try_flip_waitzero(void) /* Check to see if the sum of the "last" counters is zero. */ RCU_TRACE_ME(rcupreempt_trace_try_flip_z1); - for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) + for_each_possible_cpu(cpu) sum += RCU_DATA_CPU(cpu)->rcu_flipctr[lastidx]; if (sum != 0) { RCU_TRACE_ME(rcupreempt_trace_try_flip_ze1); @@ -1067,12 +1067,6 @@ void rcu_offline_cpu(int cpu) /* seen -after- acknowledgement. */ } - RCU_DATA_ME()->rcu_flipctr[0] += RCU_DATA_CPU(cpu)->rcu_flipctr[0]; - RCU_DATA_ME()->rcu_flipctr[1] += RCU_DATA_CPU(cpu)->rcu_flipctr[1]; - - RCU_DATA_CPU(cpu)->rcu_flipctr[0] = 0; - RCU_DATA_CPU(cpu)->rcu_flipctr[1] = 0; - cpumask_clear_cpu(cpu, to_cpumask(rcu_cpu_online_map)); spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags); -- cgit v1.2.3 From b612ba804b8a656333013ad2ee96fb2377df5dbb Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 15 Aug 2009 09:53:50 -0700 Subject: rcu: Make rcupreempt_trace.c look at offline CPUs Given that offline CPUs can now have non-zero counters, we need to dump counters for offline CPUs as well as for online CPUs. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: josht@linux.vnet.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: hugh.dickins@tiscali.co.uk Cc: benh@kernel.crashing.org LKML-Reference: <12503552313921-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcupreempt_trace.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/rcupreempt_trace.c b/kernel/rcupreempt_trace.c index 7c2665cac172..11640346a507 100644 --- a/kernel/rcupreempt_trace.c +++ b/kernel/rcupreempt_trace.c @@ -236,12 +236,13 @@ static ssize_t rcuctrs_read(struct file *filp, char __user *buffer, cnt += snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE, "CPU last cur F M\n"); - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { long *flipctr = rcupreempt_flipctr(cpu); cnt += snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt, - "%3d %4ld %3ld %d %d\n", + "%3d%c %4ld %3ld %d %d\n", cpu, + cpu_is_offline(cpu) ? '!' : ' ', flipctr[!f], flipctr[f], rcupreempt_flip_flag(cpu), -- cgit v1.2.3 From 684ca5cc9a772532bc893cdc994bd89bf0773719 Mon Sep 17 00:00:00 2001 From: Josh Triplett Date: Sat, 15 Aug 2009 09:53:51 -0700 Subject: rcu: Fix typo in rcu_irq_exit() comment header Signed-off-by: Josh Triplett Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: josht@linux.vnet.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: hugh.dickins@tiscali.co.uk Cc: benh@kernel.crashing.org LKML-Reference: <1250355231169-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcupreempt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c index 2748b89910b6..510898a7bd69 100644 --- a/kernel/rcupreempt.c +++ b/kernel/rcupreempt.c @@ -548,7 +548,7 @@ void rcu_irq_enter(void) * rcu_irq_exit - Called from exiting Hard irq context. * * If the CPU was idle with dynamic ticks active, update the - * rcu_dyntick_sched.dynticks to put let the RCU handling be + * rcu_dyntick_sched.dynticks to let the RCU handling be * aware that the CPU is going back to idle with no ticks. */ void rcu_irq_exit(void) -- cgit v1.2.3 From 1423cc033df017c762a9155eec470da77a460141 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 18 Aug 2009 23:06:14 -0700 Subject: rcu: Delay rcu_barrier() wait until beginning of next CPU-hotunplug operation. Ingo Molnar reported this lockup: [ 200.380003] Hangcheck: hangcheck value past margin! [ 248.192003] INFO: task S99local:2974 blocked for more than 120 seconds. [ 248.194532] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 248.202330] S99local D 0000000c 6256 2974 2687 0x00000000 [ 248.208929] 9c7ebe90 00000086 6b67ef8b 0000000c 9f25a610 81a69869 00000001 820b6990 [ 248.216123] 820b6990 820b6990 9c6e4c20 9c6e4eb4 82c78990 00000000 6b993559 0000000c [ 248.220616] 9c7ebe90 8105f22a 9c6e4eb4 9c6e4c20 00000001 9c7ebe98 9c7ebeb4 81a65cb3 [ 248.229990] Call Trace: [ 248.234049] [<81a69869>] ? _spin_unlock_irqrestore+0x22/0x37 [ 248.239769] [<8105f22a>] ? prepare_to_wait+0x48/0x4e [ 248.244796] [<81a65cb3>] rcu_barrier_cpu_hotplug+0xaa/0xc9 [ 248.250343] [<8105f029>] ? autoremove_wake_function+0x0/0x38 [ 248.256063] [<81062cf2>] notifier_call_chain+0x49/0x71 [ 248.261263] [<81062da0>] raw_notifier_call_chain+0x11/0x13 [ 248.266809] [<81a0b475>] _cpu_down+0x272/0x288 [ 248.271316] [<81a0b4d5>] cpu_down+0x4a/0xa2 [ 248.275563] [<81a0c48a>] store_online+0x2a/0x5e [ 248.280156] [<81a0c460>] ? store_online+0x0/0x5e [ 248.284836] [<814ddc35>] sysdev_store+0x20/0x28 [ 248.289429] [<8112e403>] sysfs_write_file+0xb8/0xe3 [ 248.294369] [<8112e34b>] ? sysfs_write_file+0x0/0xe3 [ 248.299396] [<810e4c8f>] vfs_write+0x91/0x120 [ 248.303817] [<810e4dc1>] sys_write+0x40/0x65 [ 248.308150] [<81002d73>] sysenter_do_call+0x12/0x28 This change moves an RCU grace period delay off of the critical path for CPU-hotunplug operations. Since RCU callback migration is only performed on CPU-hotunplug operations, and since the rcu_barrier() race is provoked only by consecutive CPU-hotunplug operations, it is not necessary to delay the end of a given CPU-hotunplug operation. We can instead choose to delay the beginning of the next CPU-hotunplug operation. Reported-by: Ingo Molnar Signed-off-by: Paul E. McKenney Cc: Josh Triplett Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: hugh.dickins@tiscali.co.uk Cc: benh@kernel.crashing.org LKML-Reference: <20090819060614.GA14383@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar --- kernel/rcupdate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 8df115600c2d..bd5d5c8e5140 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -238,7 +238,8 @@ static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self, call_rcu_bh(rcu_migrate_head, rcu_migrate_callback); call_rcu_sched(rcu_migrate_head + 1, rcu_migrate_callback); call_rcu(rcu_migrate_head + 2, rcu_migrate_callback); - } else if (action == CPU_POST_DEAD) { + } else if (action == CPU_DOWN_PREPARE) { + /* Don't need to wait until next removal operation. */ /* rcu_migrate_head is protected by cpu_add_remove_lock */ wait_migrated_callbacks(); } -- cgit v1.2.3 From 9f77da9f40045253e91f55c12d4481254b513d2d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 22 Aug 2009 13:56:45 -0700 Subject: rcu: Move private definitions from include/linux/rcutree.h to kernel/rcutree.h Some information hiding that makes it easier to merge preemptability into rcutree without descending into #include hell. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org LKML-Reference: <1250974613373-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutree.c | 2 + kernel/rcutree.h | 238 +++++++++++++++++++++++++++++++++++++++++++++++++ kernel/rcutree_trace.c | 1 + 3 files changed, 241 insertions(+) (limited to 'kernel') diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 75762cddbe03..a162f859dd32 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -46,6 +46,8 @@ #include #include +#include "rcutree.h" + #ifdef CONFIG_DEBUG_LOCK_ALLOC static struct lock_class_key rcu_lock_key; struct lockdep_map rcu_lock_map = diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 5e872bbf07f5..7cc830a1c44a 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -1,3 +1,239 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (tree-based version) + * Internal non-public definitions. + * + * 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: Ingo Molnar + * Paul E. McKenney + */ + +#include +#include +#include +#include +#include + +/* + * Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT. + * In theory, it should be possible to add more levels straightforwardly. + * In practice, this has not been tested, so there is probably some + * bug somewhere. + */ +#define MAX_RCU_LVLS 3 +#define RCU_FANOUT (CONFIG_RCU_FANOUT) +#define RCU_FANOUT_SQ (RCU_FANOU