path: root/kernel/padata.c

/*
 * padata.c - generic interface to process data streams in parallel
 *
 * See Documentation/padata.txt for an api documentation.
 *
 * Copyright (C) 2008, 2009 secunet Security Networks AG
 * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/export.h>
#include <linux/cpumask.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/padata.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/rcupdate.h>

#define MAX_OBJ_NUM 1000

static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
{
	int cpu, target_cpu;

	target_cpu = cpumask_first(pd->cpumask.pcpu);
	for (cpu = 0; cpu < cpu_index; cpu++)
		target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);

	return target_cpu;
}

static int padata_cpu_hash(struct parallel_data *pd)
{
	int cpu_index;

	/*
	 * Hash the sequence numbers to the cpus by taking
	 * seq_nr mod. number of cpus in use.
	 */

	spin_lock(&pd->seq_lock);
	cpu_index =  pd->seq_nr % cpumask_weight(pd->cpumask.pcpu);
	pd->seq_nr++;
	spin_unlock(&pd->seq_lock);

	return padata_index_to_cpu(pd, cpu_index);
}

static void padata_parallel_worker(struct work_struct *parallel_work)
{
	struct padata_parallel_queue *pqueue;
	struct parallel_data *pd;
	struct padata_instance *pinst;
	LIST_HEAD(local_list);

	local_bh_disable();
	pqueue = container_of(parallel_work,
			      struct padata_parallel_queue, work);
	pd = pqueue->pd;
	pinst = pd->pinst;

	spin_lock(&pqueue->parallel.lock);
	list_replace_init(&pqueue->parallel.list, &local_list);
	spin_unlock(&pqueue->parallel.lock);

	while (!list_empty(&local_list)) {
		struct padata_priv *padata;

		padata = list_entry(local_list.next,
				    struct padata_priv, list);

		list_del_init(&padata->list);

		padata->parallel(padata);
	}

	local_bh_enable();
}

/**
 * padata_do_parallel - padata parallelization function
 *
 * @pinst: padata instance
 * @padata: object to be parallelized
 * @cb_cpu: cpu the serialization callback function will run on,
 *          must be in the serial cpumask of padata(i.e. cpumask.cbcpu).
 *
 * The parallelization callback function will run with BHs off.
 * Note: Every object which is parallelized by padata_do_parallel
 * must be seen by padata_do_serial.
 */
int padata_do_parallel(struct padata_instance *pinst,
		       struct padata_priv *padata, int cb_cpu)
{
	int target_cpu, err;
	struct padata_parallel_queue *queue;
	struct parallel_data *pd;

	rcu_read_lock_bh();

	pd = rcu_dereference(pinst->pd);

	err = -EINVAL;
	if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)
		goto out;

	if (!cpumask_test_cpu(cb_cpu, pd->cpumask.cbcpu))
		goto out;

	err =  -EBUSY;
	if ((pinst->flags & PADATA_RESET))
		goto out;

	if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
		goto out;

	err = 0;
	atomic_inc(&pd->refcnt);
	padata->pd = pd;
	padata->cb_cpu = cb_cpu;

	target_cpu = padata_cpu_hash(pd);
	queue = per_cpu_ptr(pd->pqueue, target_cpu);

	spin_lock(&queue->parallel.lock);
	list_add_tail(&padata->list, &</