/* * cn_queue.c * * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net> * All rights reserved. * * 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 * */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/list.h> #include <linux/workqueue.h> #include <linux/spinlock.h> #include <linux/slab.h> #include <linux/skbuff.h> #include <linux/suspend.h> #include <linux/connector.h> #include <linux/delay.h> /* * This job is sent to the kevent workqueue. * While no event is once sent to any callback, the connector workqueue * is not created to avoid a useless waiting kernel task. * Once the first event is received, we create this dedicated workqueue which * is necessary because the flow of data can be high and we don't want * to encumber keventd with that. */ static void cn_queue_create(struct work_struct *work) { struct cn_queue_dev *dev; dev = container_of(work, struct cn_queue_dev, wq_creation); dev->cn_queue = create_singlethread_workqueue(dev->name); /* If we fail, we will use keventd for all following connector jobs */ WARN_ON(!dev->cn_queue); } /* * Queue a data sent to a callback. * If the connector workqueue is already created, we queue the job on it. * Otherwise, we queue the job to kevent and queue the connector workqueue * creation too. */ int queue_cn_work(struct cn_callback_entry *cbq, struct work_struct *work) { struct cn_queue_dev *pdev = cbq->pdev; if (likely(pdev->cn_queue)) return queue_work(pdev->cn_queue, work); /* Don't create the connector workqueue twice */ if (atomic_inc_return(&pdev->wq_requested) == 1) schedule_work(&pdev->wq_creation); else atomic_dec(&pdev->wq_requested); return schedule_work(work); } void cn_queue_wrapper(struct work_struct *work) { struct cn_callback_entry *cbq = container_of(work, struct cn_callback_entry, work); struct cn_callback_data *d = &cbq->data; struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(d->skb)); struct netlink_skb_parms *nsp = &NETLINK_CB(d->skb); d->callback(msg, nsp); kfree_skb(d->skb); d->skb = NULL; kfree(d->free); } static struct cn_callback_entry * cn_queue_alloc_callback_entry(char *name, struct cb_id *id, void (*callback)(struct cn_msg *, struct netlink_skb_parms *)) { struct cn_callback_entry *cbq; cbq = kzalloc(sizeof(*cbq), GFP_KERNEL); if (!cbq) { printk(KERN_ERR "Failed to create new callback queue.\n"); return NULL; } snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name); memcpy(&cbq->id.id, id, sizeof(struct cb_id)); cbq->data.callback = callback; INIT_WORK(&cbq->work, &cn_queue_wrapper); return cbq; } static void cn_queue_free_callback(struct cn_callback_entry *cbq) { /* The first jobs have been sent to kevent, flush them too */ flush_scheduled_work(); if (cbq->pdev->cn_queue) flush_workqueue(cbq->pdev->cn_queue); kfree(cbq); } int cn_cb_equal(struct cb_id *i1, struct cb_id *i2) { return ((i1->idx == i2->idx) && (i1->val == i2->val)); } int cn_queue_add_callback(struct cn_queue_dev *dev, char *name, struct cb_id *id, void (*callback)(struct cn_msg *, struct netlink_skb_parms *)) { struct cn_callback_entry *cbq, *__cbq; int found = 0; cbq = cn_queue_alloc_callback_entry(name, id, callback); if (!cbq) return -ENOMEM; atomic_inc(&dev->refcnt); cbq->pdev = dev; spin_lock_bh(&dev->queue_lock); list_for_each_entry(__cbq, &dev->queue_list, callback_entry) { if (cn_cb_equal(&__cbq->id.id, id)) { found = 1; break; } } if (!found) list_add_tail(&cbq->callback_entry, &dev->queue_list); spin_unlock_bh(&dev->queue_lock); if (found) { cn_queue_free_callback(cbq); atomic_dec(&dev->refcnt); return -EINVAL; } cbq->seq = 0; cbq->group = cbq->id.id.idx; return 0; } void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id) { struct cn_callback_entry *cbq, *n; int found = 0; spin_lock_bh(&dev->queue_lock); list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) { if (cn_cb_equal(&cbq->id.id, id)) { list_del(&cbq->callback_entry); found = 1; break; } } spin_unlock_bh(&dev->queue_lock); if (found) { cn_queue_free_callback(cbq); atomic_dec(&dev->refcnt); } } struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls) { struct cn_queue_dev *dev; dev = kzalloc(sizeof(*dev), GFP_KERNEL); if (!dev) return NULL; snprintf(dev->name, sizeof(dev->name), "%s", name); atomic_set(&dev->refcnt, 0); INIT_LIST_HEAD(&dev->queue_list); spin_lock_init(&dev->queue_lock); init_waitqueue_head(&dev->wq_created); dev->nls = nls; INIT_WORK(&dev->wq_creation, cn_queue_create); return dev; } void cn_queue_free_dev(struct cn_queue_dev *dev) { struct cn_callback_entry *cbq, *n; long timeout; DEFINE_WAIT(wait); /* Flush the first pending jobs queued on kevent */ flush_scheduled_work(); /* If the connector workqueue creation is still pending, wait for it */ prepare_to_wait(&dev->wq_created, &wait, TASK_UNINTERRUPTIBLE); if (atomic_read(&dev->wq_requested) && !dev->cn_queue) { timeout = schedule_timeout(HZ * 2); if (!timeout && !dev->cn_queue) WARN_ON(1); } finish_wait(&dev->wq_created, &wait); if (dev->cn_queue) { flush_workqueue(dev->cn_queue); destroy_workqueue(dev->cn_queue); } spin_lock_bh(&dev->queue_lock); list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) list_del(&cbq->callback_entry); spin_unlock_bh(&dev->queue_lock); while (atomic_read(&dev->refcnt)) { printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n", dev->name, atomic_read(&dev->refcnt)); msleep(1000); } kfree(dev); dev = NULL; }