1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	cn_queue.c
4  *
5  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
6  * All rights reserved.
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/workqueue.h>
13 #include <linux/spinlock.h>
14 #include <linux/slab.h>
15 #include <linux/skbuff.h>
16 #include <linux/suspend.h>
17 #include <linux/connector.h>
18 #include <linux/delay.h>
19 
20 static struct cn_callback_entry *
cn_queue_alloc_callback_entry(struct cn_queue_dev * dev,const char * name,const struct cb_id * id,void (* callback)(struct cn_msg *,struct netlink_skb_parms *))21 cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const char *name,
22 			      const struct cb_id *id,
23 			      void (*callback)(struct cn_msg *,
24 					       struct netlink_skb_parms *))
25 {
26 	struct cn_callback_entry *cbq;
27 
28 	cbq = kzalloc(sizeof(*cbq), GFP_KERNEL);
29 	if (!cbq) {
30 		pr_err("Failed to create new callback queue.\n");
31 		return NULL;
32 	}
33 
34 	refcount_set(&cbq->refcnt, 1);
35 
36 	atomic_inc(&dev->refcnt);
37 	cbq->pdev = dev;
38 
39 	snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
40 	memcpy(&cbq->id.id, id, sizeof(struct cb_id));
41 	cbq->callback = callback;
42 	return cbq;
43 }
44 
cn_queue_release_callback(struct cn_callback_entry * cbq)45 void cn_queue_release_callback(struct cn_callback_entry *cbq)
46 {
47 	if (!refcount_dec_and_test(&cbq->refcnt))
48 		return;
49 
50 	atomic_dec(&cbq->pdev->refcnt);
51 	kfree(cbq);
52 }
53 
cn_cb_equal(const struct cb_id * i1,const struct cb_id * i2)54 int cn_cb_equal(const struct cb_id *i1, const struct cb_id *i2)
55 {
56 	return ((i1->idx == i2->idx) && (i1->val == i2->val));
57 }
58 
cn_queue_add_callback(struct cn_queue_dev * dev,const char * name,const struct cb_id * id,void (* callback)(struct cn_msg *,struct netlink_skb_parms *))59 int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,
60 			  const struct cb_id *id,
61 			  void (*callback)(struct cn_msg *,
62 					   struct netlink_skb_parms *))
63 {
64 	struct cn_callback_entry *cbq, *__cbq;
65 	int found = 0;
66 
67 	cbq = cn_queue_alloc_callback_entry(dev, name, id, callback);
68 	if (!cbq)
69 		return -ENOMEM;
70 
71 	spin_lock_bh(&dev->queue_lock);
72 	list_for_each_entry(__cbq, &dev->queue_list, callback_entry) {
73 		if (cn_cb_equal(&__cbq->id.id, id)) {
74 			found = 1;
75 			break;
76 		}
77 	}
78 	if (!found)
79 		list_add_tail(&cbq->callback_entry, &dev->queue_list);
80 	spin_unlock_bh(&dev->queue_lock);
81 
82 	if (found) {
83 		cn_queue_release_callback(cbq);
84 		return -EINVAL;
85 	}
86 
87 	cbq->seq = 0;
88 	cbq->group = cbq->id.id.idx;
89 
90 	return 0;
91 }
92 
cn_queue_del_callback(struct cn_queue_dev * dev,const struct cb_id * id)93 void cn_queue_del_callback(struct cn_queue_dev *dev, const struct cb_id *id)
94 {
95 	struct cn_callback_entry *cbq, *n;
96 	int found = 0;
97 
98 	spin_lock_bh(&dev->queue_lock);
99 	list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) {
100 		if (cn_cb_equal(&cbq->id.id, id)) {
101 			list_del(&cbq->callback_entry);
102 			found = 1;
103 			break;
104 		}
105 	}
106 	spin_unlock_bh(&dev->queue_lock);
107 
108 	if (found)
109 		cn_queue_release_callback(cbq);
110 }
111 
cn_queue_alloc_dev(const char * name,struct sock * nls)112 struct cn_queue_dev *cn_queue_alloc_dev(const char *name, struct sock *nls)
113 {
114 	struct cn_queue_dev *dev;
115 
116 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
117 	if (!dev)
118 		return NULL;
119 
120 	snprintf(dev->name, sizeof(dev->name), "%s", name);
121 	atomic_set(&dev->refcnt, 0);
122 	INIT_LIST_HEAD(&dev->queue_list);
123 	spin_lock_init(&dev->queue_lock);
124 
125 	dev->nls = nls;
126 
127 	return dev;
128 }
129 
cn_queue_free_dev(struct cn_queue_dev * dev)130 void cn_queue_free_dev(struct cn_queue_dev *dev)
131 {
132 	struct cn_callback_entry *cbq, *n;
133 
134 	spin_lock_bh(&dev->queue_lock);
135 	list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry)
136 		list_del(&cbq->callback_entry);
137 	spin_unlock_bh(&dev->queue_lock);
138 
139 	while (atomic_read(&dev->refcnt)) {
140 		pr_info("Waiting for %s to become free: refcnt=%d.\n",
141 		       dev->name, atomic_read(&dev->refcnt));
142 		msleep(1000);
143 	}
144 
145 	kfree(dev);
146 	dev = NULL;
147 }
148