1 /*
2 * net/tipc/log.c: TIPC print buffer routines for debugging
3 *
4 * Copyright (c) 1996-2006, Ericsson AB
5 * Copyright (c) 2005-2007, Wind River Systems
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the names of the copyright holders nor the names of its
17 * contributors may be used to endorse or promote products derived from
18 * this software without specific prior written permission.
19 *
20 * Alternatively, this software may be distributed under the terms of the
21 * GNU General Public License ("GPL") version 2 as published by the Free
22 * Software Foundation.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
28 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34 * POSSIBILITY OF SUCH DAMAGE.
35 */
36
37 #include "core.h"
38 #include "config.h"
39 #include "log.h"
40
41 /*
42 * TIPC pre-defines the following print buffers:
43 *
44 * TIPC_NULL : null buffer (i.e. print nowhere)
45 * TIPC_CONS : system console
46 * TIPC_LOG : TIPC log buffer
47 *
48 * Additional user-defined print buffers are also permitted.
49 */
50
51 static struct print_buf null_buf = { NULL, 0, NULL, 0 };
52 struct print_buf *const TIPC_NULL = &null_buf;
53
54 static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
55 struct print_buf *const TIPC_CONS = &cons_buf;
56
57 static struct print_buf log_buf = { NULL, 0, NULL, 1 };
58 struct print_buf *const TIPC_LOG = &log_buf;
59
60 /*
61 * Locking policy when using print buffers.
62 *
63 * 1) tipc_printf() uses 'print_lock' to protect against concurrent access to
64 * 'print_string' when writing to a print buffer. This also protects against
65 * concurrent writes to the print buffer being written to.
66 *
67 * 2) tipc_log_XXX() leverages the aforementioned use of 'print_lock' to
68 * protect against all types of concurrent operations on their associated
69 * print buffer (not just write operations).
70 *
71 * Note: All routines of the form tipc_printbuf_XXX() are lock-free, and rely
72 * on the caller to prevent simultaneous use of the print buffer(s) being
73 * manipulated.
74 */
75
76 static char print_string[TIPC_PB_MAX_STR];
77 static DEFINE_SPINLOCK(print_lock);
78
79 static void tipc_printbuf_move(struct print_buf *pb_to,
80 struct print_buf *pb_from);
81
82 #define FORMAT(PTR, LEN, FMT) \
83 {\
84 va_list args;\
85 va_start(args, FMT);\
86 LEN = vsprintf(PTR, FMT, args);\
87 va_end(args);\
88 *(PTR + LEN) = '\0';\
89 }
90
91 /**
92 * tipc_printbuf_init - initialize print buffer to empty
93 * @pb: pointer to print buffer structure
94 * @raw: pointer to character array used by print buffer
95 * @size: size of character array
96 *
97 * Note: If the character array is too small (or absent), the print buffer
98 * becomes a null device that discards anything written to it.
99 */
100
tipc_printbuf_init(struct print_buf * pb,char * raw,u32 size)101 void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
102 {
103 pb->buf = raw;
104 pb->crs = raw;
105 pb->size = size;
106 pb->echo = 0;
107
108 if (size < TIPC_PB_MIN_SIZE) {
109 pb->buf = NULL;
110 } else if (raw) {
111 pb->buf[0] = 0;
112 pb->buf[size - 1] = ~0;
113 }
114 }
115
116 /**
117 * tipc_printbuf_reset - reinitialize print buffer to empty state
118 * @pb: pointer to print buffer structure
119 */
120
tipc_printbuf_reset(struct print_buf * pb)121 static void tipc_printbuf_reset(struct print_buf *pb)
122 {
123 if (pb->buf) {
124 pb->crs = pb->buf;
125 pb->buf[0] = 0;
126 pb->buf[pb->size - 1] = ~0;
127 }
128 }
129
130 /**
131 * tipc_printbuf_empty - test if print buffer is in empty state
132 * @pb: pointer to print buffer structure
133 *
134 * Returns non-zero if print buffer is empty.
135 */
136
tipc_printbuf_empty(struct print_buf * pb)137 static int tipc_printbuf_empty(struct print_buf *pb)
138 {
139 return !pb->buf || (pb->crs == pb->buf);
140 }
141
142 /**
143 * tipc_printbuf_validate - check for print buffer overflow
144 * @pb: pointer to print buffer structure
145 *
146 * Verifies that a print buffer has captured all data written to it.
147 * If data has been lost, linearize buffer and prepend an error message
148 *
149 * Returns length of print buffer data string (including trailing NUL)
150 */
151
tipc_printbuf_validate(struct print_buf * pb)152 int tipc_printbuf_validate(struct print_buf *pb)
153 {
154 char *err = "\n\n*** PRINT BUFFER OVERFLOW ***\n\n";
155 char *cp_buf;
156 struct print_buf cb;
157
158 if (!pb->buf)
159 return 0;
160
161 if (pb->buf[pb->size - 1] == 0) {
162 cp_buf = kmalloc(pb->size, GFP_ATOMIC);
163 if (cp_buf) {
164 tipc_printbuf_init(&cb, cp_buf, pb->size);
165 tipc_printbuf_move(&cb, pb);
166 tipc_printbuf_move(pb, &cb);
167 kfree(cp_buf);
168 memcpy(pb->buf, err, strlen(err));
169 } else {
170 tipc_printbuf_reset(pb);
171 tipc_printf(pb, err);
172 }
173 }
174 return pb->crs - pb->buf + 1;
175 }
176
177 /**
178 * tipc_printbuf_move - move print buffer contents to another print buffer
179 * @pb_to: pointer to destination print buffer structure
180 * @pb_from: pointer to source print buffer structure
181 *
182 * Current contents of destination print buffer (if any) are discarded.
183 * Source print buffer becomes empty if a successful move occurs.
184 */
185
tipc_printbuf_move(struct print_buf * pb_to,struct print_buf * pb_from)186 static void tipc_printbuf_move(struct print_buf *pb_to,
187 struct print_buf *pb_from)
188 {
189 int len;
190
191 /* Handle the cases where contents can't be moved */
192
193 if (!pb_to->buf)
194 return;
195
196 if (!pb_from->buf) {
197 tipc_printbuf_reset(pb_to);
198 return;
199 }
200
201 if (pb_to->size < pb_from->size) {
202 strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
203 pb_to->buf[pb_to->size - 1] = ~0;
204 pb_to->crs = strchr(pb_to->buf, 0);
205 return;
206 }
207
208 /* Copy data from char after cursor to end (if used) */
209
210 len = pb_from->buf + pb_from->size - pb_from->crs - 2;
211 if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
212 strcpy(pb_to->buf, pb_from->crs + 1);
213 pb_to->crs = pb_to->buf + len;
214 } else
215 pb_to->crs = pb_to->buf;
216
217 /* Copy data from start to cursor (always) */
218
219 len = pb_from->crs - pb_from->buf;
220 strcpy(pb_to->crs, pb_from->buf);
221 pb_to->crs += len;
222
223 tipc_printbuf_reset(pb_from);
224 }
225
226 /**
227 * tipc_printf - append formatted output to print buffer
228 * @pb: pointer to print buffer
229 * @fmt: formatted info to be printed
230 */
231
tipc_printf(struct print_buf * pb,const char * fmt,...)232 void tipc_printf(struct print_buf *pb, const char *fmt, ...)
233 {
234 int chars_to_add;
235 int chars_left;
236 char save_char;
237
238 spin_lock_bh(&print_lock);
239
240 FORMAT(print_string, chars_to_add, fmt);
241 if (chars_to_add >= TIPC_PB_MAX_STR)
242 strcpy(print_string, "*** PRINT BUFFER STRING TOO LONG ***");
243
244 if (pb->buf) {
245 chars_left = pb->buf + pb->size - pb->crs - 1;
246 if (chars_to_add <= chars_left) {
247 strcpy(pb->crs, print_string);
248 pb->crs += chars_to_add;
249 } else if (chars_to_add >= (pb->size - 1)) {
250 strcpy(pb->buf, print_string + chars_to_add + 1
251 - pb->size);
252 pb->crs = pb->buf + pb->size - 1;
253 } else {
254 strcpy(pb->buf, print_string + chars_left);
255 save_char = print_string[chars_left];
256 print_string[chars_left] = 0;
257 strcpy(pb->crs, print_string);
258 print_string[chars_left] = save_char;
259 pb->crs = pb->buf + chars_to_add - chars_left;
260 }
261 }
262
263 if (pb->echo)
264 printk("%s", print_string);
265
266 spin_unlock_bh(&print_lock);
267 }
268
269 /**
270 * tipc_log_resize - change the size of the TIPC log buffer
271 * @log_size: print buffer size to use
272 */
273
tipc_log_resize(int log_size)274 int tipc_log_resize(int log_size)
275 {
276 int res = 0;
277
278 spin_lock_bh(&print_lock);
279 kfree(TIPC_LOG->buf);
280 TIPC_LOG->buf = NULL;
281 if (log_size) {
282 if (log_size < TIPC_PB_MIN_SIZE)
283 log_size = TIPC_PB_MIN_SIZE;
284 res = TIPC_LOG->echo;
285 tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
286 log_size);
287 TIPC_LOG->echo = res;
288 res = !TIPC_LOG->buf;
289 }
290 spin_unlock_bh(&print_lock);
291
292 return res;
293 }
294
295 /**
296 * tipc_log_resize_cmd - reconfigure size of TIPC log buffer
297 */
298
tipc_log_resize_cmd(const void * req_tlv_area,int req_tlv_space)299 struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
300 {
301 u32 value;
302
303 if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
304 return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
305
306 value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
307 if (value > 32768)
308 return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
309 " (log size must be 0-32768)");
310 if (tipc_log_resize(value))
311 return tipc_cfg_reply_error_string(
312 "unable to create specified log (log size is now 0)");
313 return tipc_cfg_reply_none();
314 }
315
316 /**
317 * tipc_log_dump - capture TIPC log buffer contents in configuration message
318 */
319
tipc_log_dump(void)320 struct sk_buff *tipc_log_dump(void)
321 {
322 struct sk_buff *reply;
323
324 spin_lock_bh(&print_lock);
325 if (!TIPC_LOG->buf) {
326 spin_unlock_bh(&print_lock);
327 reply = tipc_cfg_reply_ultra_string("log not activated\n");
328 } else if (tipc_printbuf_empty(TIPC_LOG)) {
329 spin_unlock_bh(&print_lock);
330 reply = tipc_cfg_reply_ultra_string("log is empty\n");
331 } else {
332 struct tlv_desc *rep_tlv;
333 struct print_buf pb;
334 int str_len;
335
336 str_len = min(TIPC_LOG->size, 32768u);
337 spin_unlock_bh(&print_lock);
338 reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
339 if (reply) {
340 rep_tlv = (struct tlv_desc *)reply->data;
341 tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
342 spin_lock_bh(&print_lock);
343 tipc_printbuf_move(&pb, TIPC_LOG);
344 spin_unlock_bh(&print_lock);
345 str_len = strlen(TLV_DATA(rep_tlv)) + 1;
346 skb_put(reply, TLV_SPACE(str_len));
347 TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);
348 }
349 }
350 return reply;
351 }
352