net/tipc/log.c

   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
 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
 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
 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
 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
 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
 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
 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
 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 != delimit(value, 0, 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
 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 }