1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
/*
* 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;
}
|
