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
  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_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
  76 static char print_string[TIPC_PB_MAX_STR];
  77 static 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
  99 void 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
 119 void 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
 135 int 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
 150 int 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
 184 void 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
 229 void 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(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
 272 static 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
 292 static 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
 318 void 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
 346 int 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
 373 struct 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
 394 struct 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