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 static 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 static void tipc_printbuf_reset(struct print_buf *pb);
  80 static int  tipc_printbuf_empty(struct print_buf *pb);
  81 static void tipc_printbuf_move(struct print_buf *pb_to,
  82                                struct print_buf *pb_from);
  83
  84 #define FORMAT(PTR,LEN,FMT) \
  85 {\
  86        va_list args;\
  87        va_start(args, FMT);\
  88        LEN = vsprintf(PTR, FMT, args);\
  89        va_end(args);\
  90        *(PTR + LEN) = '\0';\
  91 }
  92
  93 /**
  94  * tipc_printbuf_init - initialize print buffer to empty
  95  * @pb: pointer to print buffer structure
  96  * @raw: pointer to character array used by print buffer
  97  * @size: size of character array
  98  *
  99  * Note: If the character array is too small (or absent), the print buffer
 100  * becomes a null device that discards anything written to it.
 101  */
 102
 103 void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
 104 {
 105         pb->buf = raw;
 106         pb->crs = raw;
 107         pb->size = size;
 108         pb->echo = 0;
 109
 110         if (size < TIPC_PB_MIN_SIZE) {
 111                 pb->buf = NULL;
 112         } else if (raw) {
 113                 pb->buf[0] = 0;
 114                 pb->buf[size - 1] = ~0;
 115         }
 116 }
 117
 118 /**
 119  * tipc_printbuf_reset - reinitialize print buffer to empty state
 120  * @pb: pointer to print buffer structure
 121  */
 122
 123 static void tipc_printbuf_reset(struct print_buf *pb)
 124 {
 125         if (pb->buf) {
 126                 pb->crs = pb->buf;
 127                 pb->buf[0] = 0;
 128                 pb->buf[pb->size - 1] = ~0;
 129         }
 130 }
 131
 132 /**
 133  * tipc_printbuf_empty - test if print buffer is in empty state
 134  * @pb: pointer to print buffer structure
 135  *
 136  * Returns non-zero if print buffer is empty.
 137  */
 138
 139 static int tipc_printbuf_empty(struct print_buf *pb)
 140 {
 141         return !pb->buf || (pb->crs == pb->buf);
 142 }
 143
 144 /**
 145  * tipc_printbuf_validate - check for print buffer overflow
 146  * @pb: pointer to print buffer structure
 147  *
 148  * Verifies that a print buffer has captured all data written to it.
 149  * If data has been lost, linearize buffer and prepend an error message
 150  *
 151  * Returns length of print buffer data string (including trailing NUL)
 152  */
 153
 154 int tipc_printbuf_validate(struct print_buf *pb)
 155 {
 156         char *err = "\n\n*** PRINT BUFFER OVERFLOW ***\n\n";
 157         char *cp_buf;
 158         struct print_buf cb;
 159
 160         if (!pb->buf)
 161                 return 0;
 162
 163         if (pb->buf[pb->size - 1] == 0) {
 164                 cp_buf = kmalloc(pb->size, GFP_ATOMIC);
 165                 if (cp_buf) {
 166                         tipc_printbuf_init(&cb, cp_buf, pb->size);
 167                         tipc_printbuf_move(&cb, pb);
 168                         tipc_printbuf_move(pb, &cb);
 169                         kfree(cp_buf);
 170                         memcpy(pb->buf, err, strlen(err));
 171                 } else {
 172                         tipc_printbuf_reset(pb);
 173                         tipc_printf(pb, err);
 174                 }
 175         }
 176         return pb->crs - pb->buf + 1;
 177 }
 178
 179 /**
 180  * tipc_printbuf_move - move print buffer contents to another print buffer
 181  * @pb_to: pointer to destination print buffer structure
 182  * @pb_from: pointer to source print buffer structure
 183  *
 184  * Current contents of destination print buffer (if any) are discarded.
 185  * Source print buffer becomes empty if a successful move occurs.
 186  */
 187
 188 static void tipc_printbuf_move(struct print_buf *pb_to,
 189                                struct print_buf *pb_from)
 190 {
 191         int len;
 192
 193         /* Handle the cases where contents can't be moved */
 194
 195         if (!pb_to->buf)
 196                 return;
 197
 198         if (!pb_from->buf) {
 199                 tipc_printbuf_reset(pb_to);
 200                 return;
 201         }
 202
 203         if (pb_to->size < pb_from->size) {
 204                 strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
 205                 pb_to->buf[pb_to->size - 1] = ~0;
 206                 pb_to->crs = strchr(pb_to->buf, 0);
 207                 return;
 208         }
 209
 210         /* Copy data from char after cursor to end (if used) */
 211
 212         len = pb_from->buf + pb_from->size - pb_from->crs - 2;
 213         if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
 214                 strcpy(pb_to->buf, pb_from->crs + 1);
 215                 pb_to->crs = pb_to->buf + len;
 216         } else
 217                 pb_to->crs = pb_to->buf;
 218
 219         /* Copy data from start to cursor (always) */
 220
 221         len = pb_from->crs - pb_from->buf;
 222         strcpy(pb_to->crs, pb_from->buf);
 223         pb_to->crs += len;
 224
 225         tipc_printbuf_reset(pb_from);
 226 }
 227
 228 /**
 229  * tipc_printf - append formatted output to print buffer
 230  * @pb: pointer to print buffer
 231  * @fmt: formatted info to be printed
 232  */
 233
 234 void tipc_printf(struct print_buf *pb, const char *fmt, ...)
 235 {
 236         int chars_to_add;
 237         int chars_left;
 238         char save_char;
 239
 240         spin_lock_bh(&print_lock);
 241
 242         FORMAT(print_string, chars_to_add, fmt);
 243         if (chars_to_add >= TIPC_PB_MAX_STR)
 244                 strcpy(print_string, "*** PRINT BUFFER STRING TOO LONG ***");
 245
 246         if (pb->buf) {
 247                 chars_left = pb->buf + pb->size - pb->crs - 1;
 248                 if (chars_to_add <= chars_left) {
 249                         strcpy(pb->crs, print_string);
 250                         pb->crs += chars_to_add;
 251                 } else if (chars_to_add >= (pb->size - 1)) {
 252                         strcpy(pb->buf, print_string + chars_to_add + 1
 253                                - pb->size);
 254                         pb->crs = pb->buf + pb->size - 1;
 255                 } else {
 256                         strcpy(pb->buf, print_string + chars_left);
 257                         save_char = print_string[chars_left];
 258                         print_string[chars_left] = 0;
 259                         strcpy(pb->crs, print_string);
 260                         print_string[chars_left] = save_char;
 261                         pb->crs = pb->buf + chars_to_add - chars_left;
 262                 }
 263         }
 264
 265         if (pb->echo)
 266                 printk("%s", print_string);
 267
 268         spin_unlock_bh(&print_lock);
 269 }
 270
 271 #ifdef CONFIG_TIPC_DEBUG
 272
 273 /**
 274  * print_to_console - write string of bytes to console in multiple chunks
 275  */
 276
 277 static void print_to_console(char *crs, int len)
 278 {
 279         int rest = len;
 280
 281         while (rest > 0) {
 282                 int sz = rest < TIPC_PB_MAX_STR ? rest : TIPC_PB_MAX_STR;
 283                 char c = crs[sz];
 284
 285                 crs[sz] = 0;
 286                 printk((const char *)crs);
 287                 crs[sz] = c;
 288                 rest -= sz;
 289                 crs += sz;
 290         }
 291 }
 292
 293 /**
 294  * printbuf_dump - write print buffer contents to console
 295  */
 296
 297 static void printbuf_dump(struct print_buf *pb)
 298 {
 299         int len;
 300
 301         if (!pb->buf) {
 302                 printk("*** PRINT BUFFER NOT ALLOCATED ***");
 303                 return;
 304         }
 305
 306         /* Dump print buffer from char after cursor to end (if used) */
 307
 308         len = pb->buf + pb->size - pb->crs - 2;
 309         if ((pb->buf[pb->size - 1] == 0) && (len > 0))
 310                 print_to_console(pb->crs + 1, len);
 311
 312         /* Dump print buffer from start to cursor (always) */
 313
 314         len = pb->crs - pb->buf;
 315         print_to_console(pb->buf, len);
 316 }
 317
 318 /**
 319  * tipc_dump_dbg - dump (non-console) print buffer to console
 320  * @pb: pointer to print buffer
 321  */
 322
 323 void tipc_dump_dbg(struct print_buf *pb, const char *fmt, ...)
 324 {
 325         int len;
 326
 327         if (pb == TIPC_CONS)
 328                 return;
 329
 330         spin_lock_bh(&print_lock);
 331
 332         FORMAT(print_string, len, fmt);
 333         printk(print_string);
 334
 335         printk("\n---- Start of %s log dump ----\n\n",
 336                (pb == TIPC_LOG) ? "global" : "local");
 337         printbuf_dump(pb);
 338         tipc_printbuf_reset(pb);
 339         printk("\n---- End of dump ----\n");
 340
 341         spin_unlock_bh(&print_lock);
 342 }
 343
 344 #endif
 345
 346 /**
 347  * tipc_log_resize - change the size of the TIPC log buffer
 348  * @log_size: print buffer size to use
 349  */
 350
 351 int tipc_log_resize(int log_size)
 352 {
 353         int res = 0;
 354
 355         spin_lock_bh(&print_lock);
 356         if (TIPC_LOG->buf) {
 357                 kfree(TIPC_LOG->buf);
 358                 TIPC_LOG->buf = NULL;
 359         }
 360         if (log_size) {
 361                 if (log_size < TIPC_PB_MIN_SIZE)
 362                         log_size = TIPC_PB_MIN_SIZE;
 363                 res = TIPC_LOG->echo;
 364                 tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
 365                                    log_size);
 366                 TIPC_LOG->echo = res;
 367                 res = !TIPC_LOG->buf;
 368         }
 369         spin_unlock_bh(&print_lock);
 370
 371         return res;
 372 }
 373
 374 /**
 375  * tipc_log_resize_cmd - reconfigure size of TIPC log buffer
 376  */
 377
 378 struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
 379 {
 380         u32 value;
 381
 382         if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
 383                 return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
 384
 385         value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
 386         if (value != delimit(value, 0, 32768))
 387                 return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
 388                                                    " (log size must be 0-32768)");
 389         if (tipc_log_resize(value))
 390                 return tipc_cfg_reply_error_string(
 391                         "unable to create specified log (log size is now 0)");
 392         return tipc_cfg_reply_none();
 393 }
 394
 395 /**
 396  * tipc_log_dump - capture TIPC log buffer contents in configuration message
 397  */
 398
 399 struct sk_buff *tipc_log_dump(void)
 400 {
 401         struct sk_buff *reply;
 402
 403         spin_lock_bh(&print_lock);
 404         if (!TIPC_LOG->buf) {
 405                 spin_unlock_bh(&print_lock);
 406                 reply = tipc_cfg_reply_ultra_string("log not activated\n");
 407         } else if (tipc_printbuf_empty(TIPC_LOG)) {
 408                 spin_unlock_bh(&print_lock);
 409                 reply = tipc_cfg_reply_ultra_string("log is empty\n");
 410         }
 411         else {
 412                 struct tlv_desc *rep_tlv;
 413                 struct print_buf pb;
 414                 int str_len;
 415
 416                 str_len = min(TIPC_LOG->size, 32768u);
 417                 spin_unlock_bh(&print_lock);
 418                 reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
 419                 if (reply) {
 420                         rep_tlv = (struct tlv_desc *)reply->data;
 421                         tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
 422                         spin_lock_bh(&print_lock);
 423                         tipc_printbuf_move(&pb, TIPC_LOG);
 424                         spin_unlock_bh(&print_lock);
 425                         str_len = strlen(TLV_DATA(rep_tlv)) + 1;
 426                         skb_put(reply, TLV_SPACE(str_len));
 427                         TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);
 428                 }
 429         }
 430         return reply;
 431 }
 432