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 static struct class *aoe_class;
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
61 static int
discover(void)62 discover(void)
63 {
64 aoecmd_cfg(0xffff, 0xff);
65 return 0;
66 }
67
68 static int
interfaces(const char __user * str,size_t size)69 interfaces(const char __user *str, size_t size)
70 {
71 if (set_aoe_iflist(str, size)) {
72 printk(KERN_ERR
73 "aoe: could not set interface list: too many interfaces\n");
74 return -EINVAL;
75 }
76 return 0;
77 }
78
79 static int
revalidate(const char __user * str,size_t size)80 revalidate(const char __user *str, size_t size)
81 {
82 int major, minor, n;
83 ulong flags;
84 struct aoedev *d;
85 struct sk_buff *skb;
86 char buf[16];
87
88 if (size >= sizeof buf)
89 return -EINVAL;
90 buf[sizeof buf - 1] = '\0';
91 if (copy_from_user(buf, str, size))
92 return -EFAULT;
93
94 n = sscanf(buf, "e%d.%d", &major, &minor);
95 if (n != 2) {
96 pr_err("aoe: invalid device specification %s\n", buf);
97 return -EINVAL;
98 }
99 d = aoedev_by_aoeaddr(major, minor, 0);
100 if (!d)
101 return -EINVAL;
102 spin_lock_irqsave(&d->lock, flags);
103 aoecmd_cleanslate(d);
104 aoecmd_cfg(major, minor);
105 loop:
106 skb = aoecmd_ata_id(d);
107 spin_unlock_irqrestore(&d->lock, flags);
108 /* try again if we are able to sleep a bit,
109 * otherwise give up this revalidation
110 */
111 if (!skb && !msleep_interruptible(250)) {
112 spin_lock_irqsave(&d->lock, flags);
113 goto loop;
114 }
115 aoedev_put(d);
116 if (skb) {
117 struct sk_buff_head queue;
118 __skb_queue_head_init(&queue);
119 __skb_queue_tail(&queue, skb);
120 aoenet_xmit(&queue);
121 }
122 return 0;
123 }
124
125 void
aoechr_error(char * msg)126 aoechr_error(char *msg)
127 {
128 struct ErrMsg *em;
129 char *mp;
130 ulong flags, n;
131
132 n = strlen(msg);
133
134 spin_lock_irqsave(&emsgs_lock, flags);
135
136 em = emsgs + emsgs_tail_idx;
137 if ((em->flags & EMFL_VALID)) {
138 bail: spin_unlock_irqrestore(&emsgs_lock, flags);
139 return;
140 }
141
142 mp = kmemdup(msg, n, GFP_ATOMIC);
143 if (mp == NULL) {
144 printk(KERN_ERR "aoe: allocation failure, len=%ld\n", n);
145 goto bail;
146 }
147
148 em->msg = mp;
149 em->flags |= EMFL_VALID;
150 em->len = n;
151
152 emsgs_tail_idx++;
153 emsgs_tail_idx %= ARRAY_SIZE(emsgs);
154
155 spin_unlock_irqrestore(&emsgs_lock, flags);
156
157 if (nblocked_emsgs_readers)
158 complete(&emsgs_comp);
159 }
160
161 static ssize_t
aoechr_write(struct file * filp,const char __user * buf,size_t cnt,loff_t * offp)162 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
163 {
164 int ret = -EINVAL;
165
166 switch ((unsigned long) filp->private_data) {
167 default:
168 printk(KERN_INFO "aoe: can't write to that file.\n");
169 break;
170 case MINOR_DISCOVER:
171 ret = discover();
172 break;
173 case MINOR_INTERFACES:
174 ret = interfaces(buf, cnt);
175 break;
176 case MINOR_REVALIDATE:
177 ret = revalidate(buf, cnt);
178 break;
179 case MINOR_FLUSH:
180 ret = aoedev_flush(buf, cnt);
181 break;
182 }
183 if (ret == 0)
184 ret = cnt;
185 return ret;
186 }
187
188 static int
aoechr_open(struct inode * inode,struct file * filp)189 aoechr_open(struct inode *inode, struct file *filp)
190 {
191 int n, i;
192
193 mutex_lock(&aoechr_mutex);
194 n = iminor(inode);
195 filp->private_data = (void *) (unsigned long) n;
196
197 for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
198 if (chardevs[i].minor == n) {
199 mutex_unlock(&aoechr_mutex);
200 return 0;
201 }
202 mutex_unlock(&aoechr_mutex);
203 return -EINVAL;
204 }
205
206 static int
aoechr_rel(struct inode * inode,struct file * filp)207 aoechr_rel(struct inode *inode, struct file *filp)
208 {
209 return 0;
210 }
211
212 static ssize_t
aoechr_read(struct file * filp,char __user * buf,size_t cnt,loff_t * off)213 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
214 {
215 unsigned long n;
216 char *mp;
217 struct ErrMsg *em;
218 ssize_t len;
219 ulong flags;
220
221 n = (unsigned long) filp->private_data;
222 if (n != MINOR_ERR)
223 return -EFAULT;
224
225 spin_lock_irqsave(&emsgs_lock, flags);
226
227 for (;;) {
228 em = emsgs + emsgs_head_idx;
229 if ((em->flags & EMFL_VALID) != 0)
230 break;
231 if (filp->f_flags & O_NDELAY) {
232 spin_unlock_irqrestore(&emsgs_lock, flags);
233 return -EAGAIN;
234 }
235 nblocked_emsgs_readers++;
236
237 spin_unlock_irqrestore(&emsgs_lock, flags);
238
239 n = wait_for_completion_interruptible(&emsgs_comp);
240
241 spin_lock_irqsave(&emsgs_lock, flags);
242
243 nblocked_emsgs_readers--;
244
245 if (n) {
246 spin_unlock_irqrestore(&emsgs_lock, flags);
247 return -ERESTARTSYS;
248 }
249 }
250 if (em->len > cnt) {
251 spin_unlock_irqrestore(&emsgs_lock, flags);
252 return -EAGAIN;
253 }
254 mp = em->msg;
255 len = em->len;
256 em->msg = NULL;
257 em->flags &= ~EMFL_VALID;
258
259 emsgs_head_idx++;
260 emsgs_head_idx %= ARRAY_SIZE(emsgs);
261
262 spin_unlock_irqrestore(&emsgs_lock, flags);
263
264 n = copy_to_user(buf, mp, len);
265 kfree(mp);
266 return n == 0 ? len : -EFAULT;
267 }
268
269 static const struct file_operations aoe_fops = {
270 .write = aoechr_write,
271 .read = aoechr_read,
272 .open = aoechr_open,
273 .release = aoechr_rel,
274 .owner = THIS_MODULE,
275 .llseek = noop_llseek,
276 };
277
aoe_devnode(struct device * dev,umode_t * mode)278 static char *aoe_devnode(struct device *dev, umode_t *mode)
279 {
280 return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
281 }
282
283 int __init
aoechr_init(void)284 aoechr_init(void)
285 {
286 int n, i;
287
288 n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
289 if (n < 0) {
290 printk(KERN_ERR "aoe: can't register char device\n");
291 return n;
292 }
293 init_completion(&emsgs_comp);
294 spin_lock_init(&emsgs_lock);
295 aoe_class = class_create(THIS_MODULE, "aoe");
296 if (IS_ERR(aoe_class)) {
297 unregister_chrdev(AOE_MAJOR, "aoechr");
298 return PTR_ERR(aoe_class);
299 }
300 aoe_class->devnode = aoe_devnode;
301
302 for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
303 device_create(aoe_class, NULL,
304 MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
305 chardevs[i].name);
306
307 return 0;
308 }
309
310 void
aoechr_exit(void)311 aoechr_exit(void)
312 {
313 int i;
314
315 for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
316 device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
317 class_destroy(aoe_class);
318 unregister_chrdev(AOE_MAJOR, "aoechr");
319 }
320
321