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 | |
61 | static char *aoe_devnode(const struct device *dev, umode_t *mode) |
62 | { |
63 | return kasprintf(GFP_KERNEL, fmt: "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 |
72 | discover(void) |
73 | { |
74 | aoecmd_cfg(aoemajor: 0xffff, aoeminor: 0xff); |
75 | return 0; |
76 | } |
77 | |
78 | static int |
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 |
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(to: buf, from: str, n: 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(maj: major, min: minor, do_alloc: 0); |
110 | if (!d) |
111 | return -EINVAL; |
112 | spin_lock_irqsave(&d->lock, flags); |
113 | aoecmd_cleanslate(d); |
114 | aoecmd_cfg(aoemajor: major, aoeminor: minor); |
115 | loop: |
116 | skb = aoecmd_ata_id(d); |
117 | spin_unlock_irqrestore(lock: &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(msecs: 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(list: &queue); |
129 | __skb_queue_tail(list: &queue, newsk: skb); |
130 | aoenet_xmit(&queue); |
131 | } |
132 | return 0; |
133 | } |
134 | |
135 | void |
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(lock: &emsgs_lock, flags); |
149 | return; |
150 | } |
151 | |
152 | mp = kmemdup(p: msg, size: 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(lock: &emsgs_lock, flags); |
164 | |
165 | if (nblocked_emsgs_readers) |
166 | complete(&emsgs_comp); |
167 | } |
168 | |
169 | static ssize_t |
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(str: buf, size: cnt); |
183 | break; |
184 | case MINOR_REVALIDATE: |
185 | ret = revalidate(str: buf, size: cnt); |
186 | break; |
187 | case MINOR_FLUSH: |
188 | ret = aoedev_flush(str: buf, size: cnt); |
189 | break; |
190 | } |
191 | if (ret == 0) |
192 | ret = cnt; |
193 | return ret; |
194 | } |
195 | |
196 | static int |
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(lock: &aoechr_mutex); |
208 | return 0; |
209 | } |
210 | mutex_unlock(lock: &aoechr_mutex); |
211 | return -EINVAL; |
212 | } |
213 | |
214 | static int |
215 | aoechr_rel(struct inode *inode, struct file *filp) |
216 | { |
217 | return 0; |
218 | } |
219 | |
220 | static ssize_t |
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(lock: &emsgs_lock, flags); |
241 | return -EAGAIN; |
242 | } |
243 | nblocked_emsgs_readers++; |
244 | |
245 | spin_unlock_irqrestore(lock: &emsgs_lock, flags); |
246 | |
247 | n = wait_for_completion_interruptible(x: &emsgs_comp); |
248 | |
249 | spin_lock_irqsave(&emsgs_lock, flags); |
250 | |
251 | nblocked_emsgs_readers--; |
252 | |
253 | if (n) { |
254 | spin_unlock_irqrestore(lock: &emsgs_lock, flags); |
255 | return -ERESTARTSYS; |
256 | } |
257 | } |
258 | if (em->len > cnt) { |
259 | spin_unlock_irqrestore(lock: &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(lock: &emsgs_lock, flags); |
271 | |
272 | n = copy_to_user(to: buf, from: mp, n: len); |
273 | kfree(objp: 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 |
287 | aoechr_init(void) |
288 | { |
289 | int n, i; |
290 | |
291 | n = register_chrdev(AOE_MAJOR, name: "aoechr" , fops: &aoe_fops); |
292 | if (n < 0) { |
293 | printk(KERN_ERR "aoe: can't register char device\n" ); |
294 | return n; |
295 | } |
296 | init_completion(x: &emsgs_comp); |
297 | spin_lock_init(&emsgs_lock); |
298 | n = class_register(class: &aoe_class); |
299 | if (n) { |
300 | unregister_chrdev(AOE_MAJOR, name: "aoechr" ); |
301 | return n; |
302 | } |
303 | |
304 | for (i = 0; i < ARRAY_SIZE(chardevs); ++i) |
305 | device_create(cls: &aoe_class, NULL, |
306 | MKDEV(AOE_MAJOR, chardevs[i].minor), NULL, |
307 | fmt: chardevs[i].name); |
308 | |
309 | return 0; |
310 | } |
311 | |
312 | void |
313 | aoechr_exit(void) |
314 | { |
315 | int i; |
316 | |
317 | for (i = 0; i < ARRAY_SIZE(chardevs); ++i) |
318 | device_destroy(cls: &aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor)); |
319 | class_unregister(class: &aoe_class); |
320 | unregister_chrdev(AOE_MAJOR, name: "aoechr" ); |
321 | } |
322 | |
323 | |