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Old 07-25-2012, 11:59 PM   #1
jideesha
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kernel driver programming


anybody give explanation about this code the code link is linux/atm/ioctl.c. i am new to this i cant undersatnd
 
Old 07-26-2012, 12:23 AM   #2
kbp
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It might be better if you posted the exact part that you don't understand as there could be differences between your version and someone elses, please use code tags if you do.
 
Old 07-26-2012, 12:53 AM   #3
tallship
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Exclamation

Quote:
Originally Posted by jideesha View Post
anybody give explanation about this code the code link is linux/atm/ioctl.c. i am new to this i cant undersatnd
Sure:

http://www.kernel.org/doc/man-pages/...2/ioctl.2.html

I hope that helps

Kindest regards,

.
 
Old 07-26-2012, 07:47 AM   #4
jideesha
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below i refer the codings but i am new to this filed even i can't understand anything from this code.i dont know where i haveto start and i want the explanation of this program what are the terms used in this and meaning of that




Linux/net/atm/ioctl.c
1 /* ATM ioctl handling */
2
3 /* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
4 /* 2003 John Levon <levon@movementarian.org> */
5
6 #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
7
8 #include <linux/module.h>
9 #include <linux/kmod.h>
10 #include <linux/net.h> /* struct socket, struct proto_ops */
11 #include <linux/atm.h> /* ATM stuff */
12 #include <linux/atmdev.h>
13 #include <linux/atmclip.h> /* CLIP_*ENCAP */
14 #include <linux/atmarp.h> /* manifest constants */
15 #include <linux/capability.h>
16 #include <linux/sonet.h> /* for ioctls */
17 #include <linux/atmsvc.h>
18 #include <linux/atmmpc.h>
19 #include <net/atmclip.h>
20 #include <linux/atmlec.h>
21 #include <linux/mutex.h>
22 #include <asm/ioctls.h>
23 #include <net/compat.h>
24
25 #include "resources.h"
26 #include "signaling.h" /* for WAITING and sigd_attach */
27 #include "common.h"
28
29
30 static DEFINE_MUTEX(ioctl_mutex);
31 static LIST_HEAD(ioctl_list);
32
33
34 void register_atm_ioctl(struct atm_ioctl *ioctl)
35 {
36 mutex_lock(&ioctl_mutex);
37 list_add_tail(&ioctl->list, &ioctl_list);
38 mutex_unlock(&ioctl_mutex);
39 }
40 EXPORT_SYMBOL(register_atm_ioctl);
41
42 void deregister_atm_ioctl(struct atm_ioctl *ioctl)
43 {
44 mutex_lock(&ioctl_mutex);
45 list_del(&ioctl->list);
46 mutex_unlock(&ioctl_mutex);
47 }
48 EXPORT_SYMBOL(deregister_atm_ioctl);
49
50 static int do_vcc_ioctl(struct socket *sock, unsigned int cmd,
51 unsigned long arg, int compat)
52 {
53 struct sock *sk = sock->sk;
54 struct atm_vcc *vcc;
55 int error;
56 struct list_head *pos;
57 void __user *argp = (void __user *)arg;
58
59 vcc = ATM_SD(sock);
60 switch (cmd) {
61 case SIOCOUTQ:
62 if (sock->state != SS_CONNECTED ||
63 !test_bit(ATM_VF_READY, &vcc->flags)) {
64 error = -EINVAL;
65 goto done;
66 }
67 error = put_user(sk->sk_sndbuf - sk_wmem_alloc_get(sk),
68 (int __user *)argp) ? -EFAULT : 0;
69 goto done;
70 case SIOCINQ:
71 {
72 struct sk_buff *skb;
73
74 if (sock->state != SS_CONNECTED) {
75 error = -EINVAL;
76 goto done;
77 }
78 skb = skb_peek(&sk->sk_receive_queue);
79 error = put_user(skb ? skb->len : 0,
80 (int __user *)argp) ? -EFAULT : 0;
81 goto done;
82 }
83 case SIOCGSTAMP: /* borrowed from IP */
84 #ifdef CONFIG_COMPAT
85 if (compat)
86 error = compat_sock_get_timestamp(sk, argp);
87 else
88 #endif
89 error = sock_get_timestamp(sk, argp);
90 goto done;
91 case SIOCGSTAMPNS: /* borrowed from IP */
92 #ifdef CONFIG_COMPAT
93 if (compat)
94 error = compat_sock_get_timestampns(sk, argp);
95 else
96 #endif
97 error = sock_get_timestampns(sk, argp);
98 goto done;
99 case ATM_SETSC:
100 if (net_ratelimit())
101 pr_warning("ATM_SETSC is obsolete; used by %s:%d\n",
102 current->comm, task_pid_nr(current));
103 error = 0;
104 goto done;
105 case ATMSIGD_CTRL:
106 if (!capable(CAP_NET_ADMIN)) {
107 error = -EPERM;
108 goto done;
109 }
110 /*
111 * The user/kernel protocol for exchanging signalling
112 * info uses kernel pointers as opaque references,
113 * so the holder of the file descriptor can scribble
114 * on the kernel... so we should make sure that we
115 * have the same privileges that /proc/kcore needs
116 */
117 if (!capable(CAP_SYS_RAWIO)) {
118 error = -EPERM;
119 goto done;
120 }
121 #ifdef CONFIG_COMPAT
122 /* WTF? I don't even want to _think_ about making this
123 work for 32-bit userspace. TBH I don't really want
124 to think about it at all. dwmw2. */
125 if (compat) {
126 if (net_ratelimit())
127 pr_warning("32-bit task cannot be atmsigd\n");
128 error = -EINVAL;
129 goto done;
130 }
131 #endif
132 error = sigd_attach(vcc);
133 if (!error)
134 sock->state = SS_CONNECTED;
135 goto done;
136 case ATM_SETBACKEND:
137 case ATM_NEWBACKENDIF:
138 {
139 atm_backend_t backend;
140 error = get_user(backend, (atm_backend_t __user *)argp);
141 if (error)
142 goto done;
143 switch (backend) {
144 case ATM_BACKEND_PPP:
145 request_module("pppoatm");
146 break;
147 case ATM_BACKEND_BR2684:
148 request_module("br2684");
149 break;
150 }
151 break;
152 }
153 case ATMMPC_CTRL:
154 case ATMMPC_DATA:
155 request_module("mpoa");
156 break;
157 case ATMARPD_CTRL:
158 request_module("clip");
159 break;
160 case ATMLEC_CTRL:
161 request_module("lec");
162 break;
163 }
164
165 error = -ENOIOCTLCMD;
166
167 mutex_lock(&ioctl_mutex);
168 list_for_each(pos, &ioctl_list) {
169 struct atm_ioctl *ic = list_entry(pos, struct atm_ioctl, list);
170 if (try_module_get(ic->owner)) {
171 error = ic->ioctl(sock, cmd, arg);
172 module_put(ic->owner);
173 if (error != -ENOIOCTLCMD)
174 break;
175 }
176 }
177 mutex_unlock(&ioctl_mutex);
178
179 if (error != -ENOIOCTLCMD)
180 goto done;
181
182 error = atm_dev_ioctl(cmd, argp, compat);
183
184 done:
185 return error;
186 }
187
188 int vcc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
189 {
190 return do_vcc_ioctl(sock, cmd, arg, 0);
191 }
192
193 #ifdef CONFIG_COMPAT
194 /*
195 * FIXME:
196 * The compat_ioctl handling is duplicated, using both these conversion
197 * routines and the compat argument to the actual handlers. Both
198 * versions are somewhat incomplete and should be merged, e.g. by
199 * moving the ioctl number translation into the actual handlers and
200 * killing the conversion code.
201 *
202 * -arnd, November 2009
203 */
204 #define ATM_GETLINKRATE32 _IOW('a', ATMIOC_ITF+1, struct compat_atmif_sioc)
205 #define ATM_GETNAMES32 _IOW('a', ATMIOC_ITF+3, struct compat_atm_iobuf)
206 #define ATM_GETTYPE32 _IOW('a', ATMIOC_ITF+4, struct compat_atmif_sioc)
207 #define ATM_GETESI32 _IOW('a', ATMIOC_ITF+5, struct compat_atmif_sioc)
208 #define ATM_GETADDR32 _IOW('a', ATMIOC_ITF+6, struct compat_atmif_sioc)
209 #define ATM_RSTADDR32 _IOW('a', ATMIOC_ITF+7, struct compat_atmif_sioc)
210 #define ATM_ADDADDR32 _IOW('a', ATMIOC_ITF+8, struct compat_atmif_sioc)
211 #define ATM_DELADDR32 _IOW('a', ATMIOC_ITF+9, struct compat_atmif_sioc)
212 #define ATM_GETCIRANGE32 _IOW('a', ATMIOC_ITF+10, struct compat_atmif_sioc)
213 #define ATM_SETCIRANGE32 _IOW('a', ATMIOC_ITF+11, struct compat_atmif_sioc)
214 #define ATM_SETESI32 _IOW('a', ATMIOC_ITF+12, struct compat_atmif_sioc)
215 #define ATM_SETESIF32 _IOW('a', ATMIOC_ITF+13, struct compat_atmif_sioc)
216 #define ATM_GETSTAT32 _IOW('a', ATMIOC_SARCOM+0, struct compat_atmif_sioc)
217 #define ATM_GETSTATZ32 _IOW('a', ATMIOC_SARCOM+1, struct compat_atmif_sioc)
218 #define ATM_GETLOOP32 _IOW('a', ATMIOC_SARCOM+2, struct compat_atmif_sioc)
219 #define ATM_SETLOOP32 _IOW('a', ATMIOC_SARCOM+3, struct compat_atmif_sioc)
220 #define ATM_QUERYLOOP32 _IOW('a', ATMIOC_SARCOM+4, struct compat_atmif_sioc)
221
222 static struct {
223 unsigned int cmd32;
224 unsigned int cmd;
225 } atm_ioctl_map[] = {
226 { ATM_GETLINKRATE32, ATM_GETLINKRATE },
227 { ATM_GETNAMES32, ATM_GETNAMES },
228 { ATM_GETTYPE32, ATM_GETTYPE },
229 { ATM_GETESI32, ATM_GETESI },
230 { ATM_GETADDR32, ATM_GETADDR },
231 { ATM_RSTADDR32, ATM_RSTADDR },
232 { ATM_ADDADDR32, ATM_ADDADDR },
233 { ATM_DELADDR32, ATM_DELADDR },
234 { ATM_GETCIRANGE32, ATM_GETCIRANGE },
235 { ATM_SETCIRANGE32, ATM_SETCIRANGE },
236 { ATM_SETESI32, ATM_SETESI },
237 { ATM_SETESIF32, ATM_SETESIF },
238 { ATM_GETSTAT32, ATM_GETSTAT },
239 { ATM_GETSTATZ32, ATM_GETSTATZ },
240 { ATM_GETLOOP32, ATM_GETLOOP },
241 { ATM_SETLOOP32, ATM_SETLOOP },
242 { ATM_QUERYLOOP32, ATM_QUERYLOOP },
243 };
244
245 #define NR_ATM_IOCTL ARRAY_SIZE(atm_ioctl_map)
246
247 static int do_atm_iobuf(struct socket *sock, unsigned int cmd,
248 unsigned long arg)
249 {
250 struct atm_iobuf __user *iobuf;
251 struct compat_atm_iobuf __user *iobuf32;
252 u32 data;
253 void __user *datap;
254 int len, err;
255
256 iobuf = compat_alloc_user_space(sizeof(*iobuf));
257 iobuf32 = compat_ptr(arg);
258
259 if (get_user(len, &iobuf32->length) ||
260 get_user(data, &iobuf32->buffer))
261 return -EFAULT;
262 datap = compat_ptr(data);
263 if (put_user(len, &iobuf->length) ||
264 put_user(datap, &iobuf->buffer))
265 return -EFAULT;
266
267 err = do_vcc_ioctl(sock, cmd, (unsigned long) iobuf, 0);
268
269 if (!err) {
270 if (copy_in_user(&iobuf32->length, &iobuf->length,
271 sizeof(int)))
272 err = -EFAULT;
273 }
274
275 return err;
276 }
277
278 static int do_atmif_sioc(struct socket *sock, unsigned int cmd,
279 unsigned long arg)
280 {
281 struct atmif_sioc __user *sioc;
282 struct compat_atmif_sioc __user *sioc32;
283 u32 data;
284 void __user *datap;
285 int err;
286
287 sioc = compat_alloc_user_space(sizeof(*sioc));
288 sioc32 = compat_ptr(arg);
289
290 if (copy_in_user(&sioc->number, &sioc32->number, 2 * sizeof(int)) ||
291 get_user(data, &sioc32->arg))
292 return -EFAULT;
293 datap = compat_ptr(data);
294 if (put_user(datap, &sioc->arg))
295 return -EFAULT;
296
297 err = do_vcc_ioctl(sock, cmd, (unsigned long) sioc, 0);
298
299 if (!err) {
300 if (copy_in_user(&sioc32->length, &sioc->length,
301 sizeof(int)))
302 err = -EFAULT;
303 }
304 return err;
305 }
306
307 static int do_atm_ioctl(struct socket *sock, unsigned int cmd32,
308 unsigned long arg)
309 {
310 int i;
311 unsigned int cmd = 0;
312
313 switch (cmd32) {
314 case SONET_GETSTAT:
315 case SONET_GETSTATZ:
316 case SONET_GETDIAG:
317 case SONET_SETDIAG:
318 case SONET_CLRDIAG:
319 case SONET_SETFRAMING:
320 case SONET_GETFRAMING:
321 case SONET_GETFRSENSE:
322 return do_atmif_sioc(sock, cmd32, arg);
323 }
324
325 for (i = 0; i < NR_ATM_IOCTL; i++) {
326 if (cmd32 == atm_ioctl_map[i].cmd32) {
327 cmd = atm_ioctl_map[i].cmd;
328 break;
329 }
330 }
331 if (i == NR_ATM_IOCTL)
332 return -EINVAL;
333
334 switch (cmd) {
335 case ATM_GETNAMES:
336 return do_atm_iobuf(sock, cmd, arg);
337
338 case ATM_GETLINKRATE:
339 case ATM_GETTYPE:
340 case ATM_GETESI:
341 case ATM_GETADDR:
342 case ATM_RSTADDR:
343 case ATM_ADDADDR:
344 case ATM_DELADDR:
345 case ATM_GETCIRANGE:
346 case ATM_SETCIRANGE:
347 case ATM_SETESI:
348 case ATM_SETESIF:
349 case ATM_GETSTAT:
350 case ATM_GETSTATZ:
351 case ATM_GETLOOP:
352 case ATM_SETLOOP:
353 case ATM_QUERYLOOP:
354 return do_atmif_sioc(sock, cmd, arg);
355 }
356
357 return -EINVAL;
358 }
359
360 int vcc_compat_ioctl(struct socket *sock, unsigned int cmd,
361 unsigned long arg)
362 {
363 int ret;
364
365 ret = do_vcc_ioctl(sock, cmd, arg, 1);
366 if (ret != -ENOIOCTLCMD)
367 return ret;
368
369 return do_atm_ioctl(sock, cmd, arg);
370 }
371 #endif
372
 
Old 07-26-2012, 08:41 AM   #5
kbp
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Why don't you start with reading this book which should explain most of the concepts you need.
 
  


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