1 files changed, 0 insertions, 285 deletions
diff --git a/kernel/srcu.c b/kernel/srcu.c
deleted file mode 100644
index 818d7d9aa03..00000000000
--- a/kernel/srcu.c
+++ /dev/null
@@ -1,285 +0,0 @@
-/*
- * Sleepable 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) IBM Corporation, 2006
- *
- * Author: Paul McKenney <paulmck@us.ibm.com>
- *
- * For detailed explanation of Read-Copy Update mechanism see -
- * 		Documentation/RCU/ *.txt
- *
- */
-
-#include <linux/module.h>
-#include <linux/mutex.h>
-#include <linux/percpu.h>
-#include <linux/preempt.h>
-#include <linux/rcupdate.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/smp.h>
-#include <linux/srcu.h>
-
-/**
- * init_srcu_struct - initialize a sleep-RCU structure
- * @sp: structure to initialize.
- *
- * Must invoke this on a given srcu_struct before passing that srcu_struct
- * to any other function.  Each srcu_struct represents a separate domain
- * of SRCU protection.
- */
-int init_srcu_struct(struct srcu_struct *sp)
-{
-	sp->completed = 0;
-	mutex_init(&sp->mutex);
-	sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
-	return (sp->per_cpu_ref ? 0 : -ENOMEM);
-}
-EXPORT_SYMBOL_GPL(init_srcu_struct);
-
-/*
- * srcu_readers_active_idx -- returns approximate number of readers
- *	active on the specified rank of per-CPU counters.
- */
-
-static int srcu_readers_active_idx(struct srcu_struct *sp, int idx)
-{
-	int cpu;
-	int sum;
-
-	sum = 0;
-	for_each_possible_cpu(cpu)
-		sum += per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx];
-	return sum;
-}
-
-/**
- * srcu_readers_active - returns approximate number of readers.
- * @sp: which srcu_struct to count active readers (holding srcu_read_lock).
- *
- * Note that this is not an atomic primitive, and can therefore suffer
- * severe errors when invoked on an active srcu_struct.  That said, it
- * can be useful as an error check at cleanup time.
- */
-static int srcu_readers_active(struct srcu_struct *sp)
-{
-	return srcu_readers_active_idx(sp, 0) + srcu_readers_active_idx(sp, 1);
-}
-
-/**
- * cleanup_srcu_struct - deconstruct a sleep-RCU structure
- * @sp: structure to clean up.
- *
- * Must invoke this after you are finished using a given srcu_struct that
- * was initialized via init_srcu_struct(), else you leak memory.
- */
-void cleanup_srcu_struct(struct srcu_struct *sp)
-{
-	int sum;
-
-	sum = srcu_readers_active(sp);
-	WARN_ON(sum);  /* Leakage unless caller handles error. */
-	if (sum != 0)
-		return;
-	free_percpu(sp->per_cpu_ref);
-	sp->per_cpu_ref = NULL;
-}
-EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
-
-/**
- * srcu_read_lock - register a new reader for an SRCU-protected structure.
- * @sp: srcu_struct in which to register the new reader.
- *
- * Counts the new reader in the appropriate per-CPU element of the
- * srcu_struct.  Must be called from process context.
- * Returns an index that must be passed to the matching srcu_read_unlock().
- */
-int srcu_read_lock(struct srcu_struct *sp)
-{
-	int idx;
-
-	preempt_disable();
-	idx = sp->completed & 0x1;
-	barrier();  /* ensure compiler looks -once- at sp->completed. */
-	per_cpu_ptr(sp->per_cpu_ref, smp_processor_id())->c[idx]++;
-	srcu_barrier();  /* ensure compiler won't misorder critical section. */
-	preempt_enable();
-	return idx;
-}
-EXPORT_SYMBOL_GPL(srcu_read_lock);
-
-/**
- * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
- * @sp: srcu_struct in which to unregister the old reader.
- * @idx: return value from corresponding srcu_read_lock().
- *
- * Removes the count for the old reader from the appropriate per-CPU
- * element of the srcu_struct.  Note that this may well be a different
- * CPU than that which was incremented by the corresponding srcu_read_lock().
- * Must be called from process context.
- */
-void srcu_read_unlock(struct srcu_struct *sp, int idx)
-{
-	preempt_disable();
-	srcu_barrier();  /* ensure compiler won't misorder critical section. */
-	per_cpu_ptr(sp->per_cpu_ref, smp_processor_id())->c[idx]--;
-	preempt_enable();
-}
-EXPORT_SYMBOL_GPL(srcu_read_unlock);
-
-/*
- * Helper function for synchronize_srcu() and synchronize_srcu_expedited().
- */
-void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
-{
-	int idx;
-
-	idx = sp->completed;
-	mutex_lock(&sp->mutex);
-
-	/*
-	 * Check to see if someone else did the work for us while we were
-	 * waiting to acquire the lock.  We need -two- advances of
-	 * the counter, not just one.  If there was but one, we might have
-	 * shown up -after- our helper's first synchronize_sched(), thus
-	 * having failed to prevent CPU-reordering races with concurrent
-	 * srcu_read_unlock()s on other CPUs (see comment below).  So we
-	 * either (1) wait for two or (2) supply the second ourselves.
-	 */
-
-	if ((sp->completed - idx) >= 2) {
-		mutex_unlock(&sp->mutex);
-		return;
-	}
-
-	sync_func();  /* Force memory barrier on all CPUs. */
-
-	/*
-	 * The preceding synchronize_sched() ensures that any CPU that
-	 * sees the new value of sp->completed will also see any preceding
-	 * changes to data structures made by this CPU.  This prevents
-	 * some other CPU from reordering the accesses in its SRCU
-	 * read-side critical section to precede the corresponding
-	 * srcu_read_lock() -- ensuring that such references will in
-	 * fact be protected.
-	 *
-	 * So it is now safe to do the flip.
-	 */
-
-	idx = sp->completed & 0x1;
-	sp->completed++;
-
-	sync_func();  /* Force memory barrier on all CPUs. */
-
-	/*
-	 * At this point, because of the preceding synchronize_sched(),
-	 * all srcu_read_lock() calls using the old counters have completed.
-	 * Their corresponding critical sections might well be still
-	 * executing, but the srcu_read_lock() primitives themselves
-	 * will have finished executing.
-	 */
-
-	while (srcu_readers_active_idx(sp, idx))
-		schedule_timeout_interruptible(1);
-
-	sync_func();  /* Force memory barrier on all CPUs. */
-
-	/*
-	 * The preceding synchronize_sched() forces all srcu_read_unlock()
-	 * primitives that were executing concurrently with the preceding
-	 * for_each_possible_cpu() loop to have completed by this point.
-	 * More importantly, it also forces the corresponding SRCU read-side
-	 * critical sections to have also completed, and the corresponding
-	 * references to SRCU-protected data items to be dropped.
-	 *
-	 * Note:
-	 *
-	 *	Despite what you might think at first glance, the
-	 *	preceding synchronize_sched() -must- be within the
-	 *	critical section ended by the following mutex_unlock().
-	 *	Otherwise, a task taking the early exit can race
-	 *	with a srcu_read_unlock(), which might have executed
-	 *	just before the preceding srcu_readers_active() check,
-	 *	and whose CPU might have reordered the srcu_read_unlock()
-	 *	with the preceding critical section.  In this case, there
-	 *	is nothing preventing the synchronize_sched() task that is
-	 *	taking the early exit from freeing a data structure that
-	 *	is still being referenced (out of order) by the task
-	 *	doing the srcu_read_unlock().
-	 *
-	 *	Alternatively, the comparison with "2" on the early exit
-	 *	could be changed to "3", but this increases synchronize_srcu()
-	 *	latency for bulk loads.  So the current code is preferred.
-	 */
-
-	mutex_unlock(&sp->mutex);
-}
-
-/**
- * synchronize_srcu - wait for prior SRCU read-side critical-section completion
- * @sp: srcu_struct with which to synchronize.
- *
- * Flip the completed counter, and wait for the old count to drain to zero.
- * As with classic RCU, the updater must use some separate means of
- * synchronizing concurrent updates.  Can block; must be called from
- * process context.
- *
- * Note that it is illegal to call synchronize_srcu() from the corresponding
- * SRCU read-side critical section; doing so will result in deadlock.
- * However, it is perfectly legal to call synchronize_srcu() on one
- * srcu_struct from some other srcu_struct's read-side critical section.
- */
-void synchronize_srcu(struct srcu_struct *sp)
-{
-	__synchronize_srcu(sp, synchronize_sched);
-}
-EXPORT_SYMBOL_GPL(synchronize_srcu);
-
-/**
- * synchronize_srcu_expedited - like synchronize_srcu, but less patient
- * @sp: srcu_struct with which to synchronize.
- *
- * Flip the completed counter, and wait for the old count to drain to zero.
- * As with classic RCU, the updater must use some separate means of
- * synchronizing concurrent updates.  Can block; must be called from
- * process context.
- *
- * Note that it is illegal to call synchronize_srcu_expedited()
- * from the corresponding SRCU read-side critical section; doing so
- * will result in deadlock.  However, it is perfectly legal to call
- * synchronize_srcu_expedited() on one srcu_struct from some other
- * srcu_struct's read-side critical section.
- */
-void synchronize_srcu_expedited(struct srcu_struct *sp)
-{
-	__synchronize_srcu(sp, synchronize_sched_expedited);
-}
-EXPORT_SYMBOL_GPL(synchronize_srcu_expedited);
-
-/**
- * srcu_batches_completed - return batches completed.
- * @sp: srcu_struct on which to report batch completion.
- *
- * Report the number of batches, correlated with, but not necessarily
- * precisely the same as, the number of grace periods that have elapsed.
- */
-
-long srcu_batches_completed(struct srcu_struct *sp)
-{
-	return sp->completed;
-}
-EXPORT_SYMBOL_GPL(srcu_batches_completed);