Root/net/tipc/dbg.c

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
428

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