1/*
2 * net/tipc/dbg.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 "dbg.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
51static struct print_buf null_buf = { NULL, 0, NULL, 0 };
52struct print_buf *const TIPC_NULL = &null_buf;
53
54static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
55struct print_buf *const TIPC_CONS = &cons_buf;
56
57static struct print_buf log_buf = { NULL, 0, NULL, 1 };
58struct 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_dump() and tipc_log_XXX() leverage the aforementioned
68 * use of 'print_lock' to protect against all types of concurrent operations
69 * on their associated 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
76static char print_string[TIPC_PB_MAX_STR];
77static DEFINE_SPINLOCK(print_lock);
78
79
80#define FORMAT(PTR,LEN,FMT) \
81{\
82       va_list args;\
83       va_start(args, FMT);\
84       LEN = vsprintf(PTR, FMT, args);\
85       va_end(args);\
86       *(PTR + LEN) = '\0';\
87}
88
89/**
90 * tipc_printbuf_init - initialize print buffer to empty
91 * @pb: pointer to print buffer structure
92 * @raw: pointer to character array used by print buffer
93 * @size: size of character array
94 *
95 * Note: If the character array is too small (or absent), the print buffer
96 * becomes a null device that discards anything written to it.
97 */
98
99void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
100{
101	pb->buf = raw;
102	pb->crs = raw;
103	pb->size = size;
104	pb->echo = 0;
105
106	if (size < TIPC_PB_MIN_SIZE) {
107		pb->buf = NULL;
108	} else if (raw) {
109		pb->buf[0] = 0;
110		pb->buf[size - 1] = ~0;
111	}
112}
113
114/**
115 * tipc_printbuf_reset - reinitialize print buffer to empty state
116 * @pb: pointer to print buffer structure
117 */
118
119void tipc_printbuf_reset(struct print_buf *pb)
120{
121	if (pb->buf) {
122		pb->crs = pb->buf;
123		pb->buf[0] = 0;
124		pb->buf[pb->size - 1] = ~0;
125	}
126}
127
128/**
129 * tipc_printbuf_empty - test if print buffer is in empty state
130 * @pb: pointer to print buffer structure
131 *
132 * Returns non-zero if print buffer is empty.
133 */
134
135int tipc_printbuf_empty(struct print_buf *pb)
136{
137	return (!pb->buf || (pb->crs == pb->buf));
138}
139
140/**
141 * tipc_printbuf_validate - check for print buffer overflow
142 * @pb: pointer to print buffer structure
143 *
144 * Verifies that a print buffer has captured all data written to it.
145 * If data has been lost, linearize buffer and prepend an error message
146 *
147 * Returns length of print buffer data string (including trailing NUL)
148 */
149
150int tipc_printbuf_validate(struct print_buf *pb)
151{
152	char *err = "\n\n*** PRINT BUFFER OVERFLOW ***\n\n";
153	char *cp_buf;
154	struct print_buf cb;
155
156	if (!pb->buf)
157		return 0;
158
159	if (pb->buf[pb->size - 1] == 0) {
160		cp_buf = kmalloc(pb->size, GFP_ATOMIC);
161		if (cp_buf) {
162			tipc_printbuf_init(&cb, cp_buf, pb->size);
163			tipc_printbuf_move(&cb, pb);
164			tipc_printbuf_move(pb, &cb);
165			kfree(cp_buf);
166			memcpy(pb->buf, err, strlen(err));
167		} else {
168			tipc_printbuf_reset(pb);
169			tipc_printf(pb, err);
170		}
171	}
172	return (pb->crs - pb->buf + 1);
173}
174
175/**
176 * tipc_printbuf_move - move print buffer contents to another print buffer
177 * @pb_to: pointer to destination print buffer structure
178 * @pb_from: pointer to source print buffer structure
179 *
180 * Current contents of destination print buffer (if any) are discarded.
181 * Source print buffer becomes empty if a successful move occurs.
182 */
183
184void tipc_printbuf_move(struct print_buf *pb_to, struct print_buf *pb_from)
185{
186	int len;
187
188	/* Handle the cases where contents can't be moved */
189
190	if (!pb_to->buf)
191		return;
192
193	if (!pb_from->buf) {
194		tipc_printbuf_reset(pb_to);
195		return;
196	}
197
198	if (pb_to->size < pb_from->size) {
199		strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
200		pb_to->buf[pb_to->size - 1] = ~0;
201		pb_to->crs = strchr(pb_to->buf, 0);
202		return;
203	}
204
205	/* Copy data from char after cursor to end (if used) */
206
207	len = pb_from->buf + pb_from->size - pb_from->crs - 2;
208	if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
209		strcpy(pb_to->buf, pb_from->crs + 1);
210		pb_to->crs = pb_to->buf + len;
211	} else
212		pb_to->crs = pb_to->buf;
213
214	/* Copy data from start to cursor (always) */
215
216	len = pb_from->crs - pb_from->buf;
217	strcpy(pb_to->crs, pb_from->buf);
218	pb_to->crs += len;
219
220	tipc_printbuf_reset(pb_from);
221}
222
223/**
224 * tipc_printf - append formatted output to print buffer
225 * @pb: pointer to print buffer
226 * @fmt: formatted info to be printed
227 */
228
229void tipc_printf(struct print_buf *pb, const char *fmt, ...)
230{
231	int chars_to_add;
232	int chars_left;
233	char save_char;
234
235	spin_lock_bh(&print_lock);
236
237	FORMAT(print_string, chars_to_add, fmt);
238	if (chars_to_add >= TIPC_PB_MAX_STR)
239		strcpy(print_string, "*** PRINT BUFFER STRING TOO LONG ***");
240
241	if (pb->buf) {
242		chars_left = pb->buf + pb->size - pb->crs - 1;
243		if (chars_to_add <= chars_left) {
244			strcpy(pb->crs, print_string);
245			pb->crs += chars_to_add;
246		} else if (chars_to_add >= (pb->size - 1)) {
247			strcpy(pb->buf, print_string + chars_to_add + 1
248			       - pb->size);
249			pb->crs = pb->buf + pb->size - 1;
250		} else {
251			strcpy(pb->buf, print_string + chars_left);
252			save_char = print_string[chars_left];
253			print_string[chars_left] = 0;
254			strcpy(pb->crs, print_string);
255			print_string[chars_left] = save_char;
256			pb->crs = pb->buf + chars_to_add - chars_left;
257		}
258	}
259
260	if (pb->echo)
261		printk("%s", print_string);
262
263	spin_unlock_bh(&print_lock);
264}
265
266#ifdef CONFIG_TIPC_DEBUG
267
268/**
269 * print_to_console - write string of bytes to console in multiple chunks
270 */
271
272static void print_to_console(char *crs, int len)
273{
274	int rest = len;
275
276	while (rest > 0) {
277		int sz = rest < TIPC_PB_MAX_STR ? rest : TIPC_PB_MAX_STR;
278		char c = crs[sz];
279
280		crs[sz] = 0;
281		printk((const char *)crs);
282		crs[sz] = c;
283		rest -= sz;
284		crs += sz;
285	}
286}
287
288/**
289 * printbuf_dump - write print buffer contents to console
290 */
291
292static void printbuf_dump(struct print_buf *pb)
293{
294	int len;
295
296	if (!pb->buf) {
297		printk("*** PRINT BUFFER NOT ALLOCATED ***");
298		return;
299	}
300
301	/* Dump print buffer from char after cursor to end (if used) */
302
303	len = pb->buf + pb->size - pb->crs - 2;
304	if ((pb->buf[pb->size - 1] == 0) && (len > 0))
305		print_to_console(pb->crs + 1, len);
306
307	/* Dump print buffer from start to cursor (always) */
308
309	len = pb->crs - pb->buf;
310	print_to_console(pb->buf, len);
311}
312
313/**
314 * tipc_dump_dbg - dump (non-console) print buffer to console
315 * @pb: pointer to print buffer
316 */
317
318void tipc_dump_dbg(struct print_buf *pb, const char *fmt, ...)
319{
320	int len;
321
322	if (pb == TIPC_CONS)
323		return;
324
325	spin_lock_bh(&print_lock);
326
327	FORMAT(print_string, len, fmt);
328	printk(print_string);
329
330	printk("\n---- Start of %s log dump ----\n\n",
331	       (pb == TIPC_LOG) ? "global" : "local");
332	printbuf_dump(pb);
333	tipc_printbuf_reset(pb);
334	printk("\n---- End of dump ----\n");
335
336	spin_unlock_bh(&print_lock);
337}
338
339#endif
340
341/**
342 * tipc_log_resize - change the size of the TIPC log buffer
343 * @log_size: print buffer size to use
344 */
345
346int tipc_log_resize(int log_size)
347{
348	int res = 0;
349
350	spin_lock_bh(&print_lock);
351	if (TIPC_LOG->buf) {
352		kfree(TIPC_LOG->buf);
353		TIPC_LOG->buf = NULL;
354	}
355	if (log_size) {
356		if (log_size < TIPC_PB_MIN_SIZE)
357			log_size = TIPC_PB_MIN_SIZE;
358		res = TIPC_LOG->echo;
359		tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
360				   log_size);
361		TIPC_LOG->echo = res;
362		res = !TIPC_LOG->buf;
363	}
364	spin_unlock_bh(&print_lock);
365
366	return res;
367}
368
369/**
370 * tipc_log_resize_cmd - reconfigure size of TIPC log buffer
371 */
372
373struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
374{
375	u32 value;
376
377	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
378		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
379
380	value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
381	if (value != delimit(value, 0, 32768))
382		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
383						   " (log size must be 0-32768)");
384	if (tipc_log_resize(value))
385		return tipc_cfg_reply_error_string(
386			"unable to create specified log (log size is now 0)");
387	return tipc_cfg_reply_none();
388}
389
390/**
391 * tipc_log_dump - capture TIPC log buffer contents in configuration message
392 */
393
394struct sk_buff *tipc_log_dump(void)
395{
396	struct sk_buff *reply;
397
398	spin_lock_bh(&print_lock);
399	if (!TIPC_LOG->buf) {
400		spin_unlock_bh(&print_lock);
401		reply = tipc_cfg_reply_ultra_string("log not activated\n");
402	} else if (tipc_printbuf_empty(TIPC_LOG)) {
403		spin_unlock_bh(&print_lock);
404		reply = tipc_cfg_reply_ultra_string("log is empty\n");
405	}
406	else {
407		struct tlv_desc *rep_tlv;
408		struct print_buf pb;
409		int str_len;
410
411		str_len = min(TIPC_LOG->size, 32768u);
412		spin_unlock_bh(&print_lock);
413		reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
414		if (reply) {
415			rep_tlv = (struct tlv_desc *)reply->data;
416			tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
417			spin_lock_bh(&print_lock);
418			tipc_printbuf_move(&pb, TIPC_LOG);
419			spin_unlock_bh(&print_lock);
420			str_len = strlen(TLV_DATA(rep_tlv)) + 1;
421			skb_put(reply, TLV_SPACE(str_len));
422			TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);
423		}
424	}
425	return reply;
426}
427