1 /* Copyright (c) 2012 Coraid, Inc. See COPYING for GPL terms. */
2 /*
3 * aoechr.c
4 * AoE character device driver
5 */
6
7 #include <linux/hdreg.h>
8 #include <linux/blkdev.h>
9 #include <linux/completion.h>
10 #include <linux/delay.h>
11 #include <linux/slab.h>
12 #include <linux/mutex.h>
13 #include <linux/skbuff.h>
14 #include <linux/export.h>
15 #include "aoe.h"
16
17 enum {
18 //MINOR_STAT = 1, (moved to sysfs)
19 MINOR_ERR = 2,
20 MINOR_DISCOVER,
21 MINOR_INTERFACES,
22 MINOR_REVALIDATE,
23 MINOR_FLUSH,
24 MSGSZ = 2048,
25 NMSG = 100, /* message backlog to retain */
26 };
27
28 struct aoe_chardev {
29 ulong minor;
30 char name[32];
31 };
32
33 enum { EMFL_VALID = 1 };
34
35 struct ErrMsg {
36 short flags;
37 short len;
38 char *msg;
39 };
40
41 static DEFINE_MUTEX(aoechr_mutex);
42
43 /* A ring buffer of error messages, to be read through
44 * "/dev/etherd/err". When no messages are present,
45 * readers will block waiting for messages to appear.
46 */
47 static struct ErrMsg emsgs[NMSG];
48 static int emsgs_head_idx, emsgs_tail_idx;
49 static struct completion emsgs_comp;
50 static spinlock_t emsgs_lock;
51 static int nblocked_emsgs_readers;
52
53 static struct aoe_chardev chardevs[] = {
54 { MINOR_ERR, "err" },
55 { MINOR_DISCOVER, "discover" },
56 { MINOR_INTERFACES, "interfaces" },
57 { MINOR_REVALIDATE, "revalidate" },
58 { MINOR_FLUSH, "flush" },
59 };
60
aoe_devnode(const struct device * dev,umode_t * mode)61 static char *aoe_devnode(const struct device *dev, umode_t *mode)
62 {
63 return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
64 }
65
66 static const struct class aoe_class = {
67 .name = "aoe",
68 .devnode = aoe_devnode,
69 };
70
71 static int
discover(void)72 discover(void)
73 {
74 aoecmd_cfg(0xffff, 0xff);
75 return 0;
76 }
77
78 static int
interfaces(const char __user * str,size_t size)79 interfaces(const char __user *str, size_t size)
80 {
81 if (set_aoe_iflist(str, size)) {
82 printk(KERN_ERR
83 "aoe: could not set interface list: too many interfaces\n");
84 return -EINVAL;
85 }
86 return 0;
87 }
88
89 static int
revalidate(const char __user * str,size_t size)90 revalidate(const char __user *str, size_t size)
91 {
92 int major, minor, n;
93 ulong flags;
94 struct aoedev *d;
95 struct sk_buff *skb;
96 char buf[16];
97
98 if (size >= sizeof buf)
99 return -EINVAL;
100 buf[sizeof buf - 1] = '\0';
101 if (copy_from_user(buf, str, size))
102 return -EFAULT;
103
104 n = sscanf(buf, "e%d.%d", &major, &minor);
105 if (n != 2) {
106 pr_err("aoe: invalid device specification %s\n", buf);
107 return -EINVAL;
108 }
109 d = aoedev_by_aoeaddr(major, minor, 0);
110 if (!d)
111 return -EINVAL;
112 spin_lock_irqsave(&d->lock, flags);
113 aoecmd_cleanslate(d);
114 aoecmd_cfg(major, minor);
115 loop:
116 skb = aoecmd_ata_id(d);
117 spin_unlock_irqrestore(&d->lock, flags);
118 /* try again if we are able to sleep a bit,
119 * otherwise give up this revalidation
120 */
121 if (!skb && !msleep_interruptible(250)) {
122 spin_lock_irqsave(&d->lock, flags);
123 goto loop;
124 }
125 aoedev_put(d);
126 if (skb) {
127 struct sk_buff_head queue;
128 __skb_queue_head_init(&queue);
129 __skb_queue_tail(&queue, skb);
130 aoenet_xmit(&queue);
131 }
132 return 0;
133 }
134
135 void
aoechr_error(char * msg)136 aoechr_error(char *msg)
137 {
138 struct ErrMsg *em;
139 char *mp;
140 ulong flags, n;
141
142 n = strlen(msg);
143
144 spin_lock_irqsave(&emsgs_lock, flags);
145
146 em = emsgs + emsgs_tail_idx;
147 if ((em->flags & EMFL_VALID)) {
148 bail: spin_unlock_irqrestore(&emsgs_lock, flags);
149 return;
150 }
151
152 mp = kmemdup(msg, n, GFP_ATOMIC);
153 if (!mp)
154 goto bail;
155
156 em->msg = mp;
157 em->flags |= EMFL_VALID;
158 em->len = n;
159
160 emsgs_tail_idx++;
161 emsgs_tail_idx %= ARRAY_SIZE(emsgs);
162
163 spin_unlock_irqrestore(&emsgs_lock, flags);
164
165 if (nblocked_emsgs_readers)
166 complete(&emsgs_comp);
167 }
168
169 static ssize_t
aoechr_write(struct file * filp,const char __user * buf,size_t cnt,loff_t * offp)170 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
171 {
172 int ret = -EINVAL;
173
174 switch ((unsigned long) filp->private_data) {
175 default:
176 printk(KERN_INFO "aoe: can't write to that file.\n");
177 break;
178 case MINOR_DISCOVER:
179 ret = discover();
180 break;
181 case MINOR_INTERFACES:
182 ret = interfaces(buf, cnt);
183 break;
184 case MINOR_REVALIDATE:
185 ret = revalidate(buf, cnt);
186 break;
187 case MINOR_FLUSH:
188 ret = aoedev_flush(buf, cnt);
189 break;
190 }
191 if (ret == 0)
192 ret = cnt;
193 return ret;
194 }
195
196 static int
aoechr_open(struct inode * inode,struct file * filp)197 aoechr_open(struct inode *inode, struct file *filp)
198 {
199 int n, i;
200
201 mutex_lock(&aoechr_mutex);
202 n = iminor(inode);
203 filp->private_data = (void *) (unsigned long) n;
204
205 for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
206 if (chardevs[i].minor == n) {
207 mutex_unlock(&aoechr_mutex);
208 return 0;
209 }
210 mutex_unlock(&aoechr_mutex);
211 return -EINVAL;
212 }
213
214 static int
aoechr_rel(struct inode * inode,struct file * filp)215 aoechr_rel(struct inode *inode, struct file *filp)
216 {
217 return 0;
218 }
219
220 static ssize_t
aoechr_read(struct file * filp,char __user * buf,size_t cnt,loff_t * off)221 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
222 {
223 unsigned long n;
224 char *mp;
225 struct ErrMsg *em;
226 ssize_t len;
227 ulong flags;
228
229 n = (unsigned long) filp->private_data;
230 if (n != MINOR_ERR)
231 return -EFAULT;
232
233 spin_lock_irqsave(&emsgs_lock, flags);
234
235 for (;;) {
236 em = emsgs + emsgs_head_idx;
237 if ((em->flags & EMFL_VALID) != 0)
238 break;
239 if (filp->f_flags & O_NDELAY) {
240 spin_unlock_irqrestore(&emsgs_lock, flags);
241 return -EAGAIN;
242 }
243 nblocked_emsgs_readers++;
244
245 spin_unlock_irqrestore(&emsgs_lock, flags);
246
247 n = wait_for_completion_interruptible(&emsgs_comp);
248
249 spin_lock_irqsave(&emsgs_lock, flags);
250
251 nblocked_emsgs_readers--;
252
253 if (n) {
254 spin_unlock_irqrestore(&emsgs_lock, flags);
255 return -ERESTARTSYS;
256 }
257 }
258 if (em->len > cnt) {
259 spin_unlock_irqrestore(&emsgs_lock, flags);
260 return -EAGAIN;
261 }
262 mp = em->msg;
263 len = em->len;
264 em->msg = NULL;
265 em->flags &= ~EMFL_VALID;
266
267 emsgs_head_idx++;
268 emsgs_head_idx %= ARRAY_SIZE(emsgs);
269
270 spin_unlock_irqrestore(&emsgs_lock, flags);
271
272 n = copy_to_user(buf, mp, len);
273 kfree(mp);
274 return n == 0 ? len : -EFAULT;
275 }
276
277 static const struct file_operations aoe_fops = {
278 .write = aoechr_write,
279 .read = aoechr_read,
280 .open = aoechr_open,
281 .release = aoechr_rel,
282 .owner = THIS_MODULE,
283 .llseek = noop_llseek,
284 };
285
286 int __init
aoechr_init(void)287 aoechr_init(void)
288 {
289 int n, i;
290
291 n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
292 if (n < 0) {
293 printk(KERN_ERR "aoe: can't register char device\n");
294 return n;
295 }
296 init_completion(&emsgs_comp);
297 spin_lock_init(&emsgs_lock);
298 n = class_register(&aoe_class);
299 if (n) {
300 unregister_chrdev(AOE_MAJOR, "aoechr");
301 return n;
302 }
303
304 for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
305 device_create(&aoe_class, NULL,
306 MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
307 chardevs[i].name);
308
309 return 0;
310 }
311
312 void
aoechr_exit(void)313 aoechr_exit(void)
314 {
315 int i;
316
317 for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
318 device_destroy(&aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
319 class_unregister(&aoe_class);
320 unregister_chrdev(AOE_MAJOR, "aoechr");
321 }
322
323